V2- PLANETS OF ORTHODONTICS- Volume II- Diagnosis and Treatment Planning.pdf

PLANETS OF
ORTHODONTICS
Authors:
Dr. Mohammed Almuzian
Specialist Orthodontist (UK)
BDS Hons (UoM), MDS Ortho. (Distinction), MSc.HCA (USA), Doctorate Clin.Dent. Ortho. (Glasgow), Cert.SR
Health (Portsmouth), PGCert.Med.Ed (Dundee), MFDRCSIre., MFDSRCSEd., MFDTRCSEd., MOrth.RCSEd.,
FDSRCSEd., MRACDS.Ortho. (Australia)
Dr. Haris Khan
Consultant Orthodontist (Pakistan)
Professor in Orthodontics (CMH Lahore Medical College)
BDS (Pakistan), FCPS Orthodontics (Pakistan), FFDRCS Ortho. (Ire.)
With
Dr. Ali Raza Jaffery
Specialist Orthodontist (Pakistan)
Associate Professor Orthodontics (Akhtar Saeed Medical and Dental College)
BDS (Pakistan), FCPS Orthodontics (Pakistan), MOrth.RCS (Edin.)
Dr. Farooq Ahmed
Consultant Orthodontist (UK)
BDS. Hons. (Manc.), MDPH (Manc.), MSc (Manc.), MFDS (RCS Ed.), PGCAP, MOrth.RCS (Eng.), FDSRCS Ortho.
(Eng.), FHEA
Volume 2
Diagnosis and Treatment Planing

Contributors
Dr. Samer Mheissen/ Specialist Orthodontist (Syria)
Dr. Mark Wertheimer/ Consultant Orthodontist (South Africa)
Dr. Mushriq Abid/ Specialist Orthodontist and Professor in Orthodontics (Iraq/ UK)
Dr. Emad E Alzoubi/ Specialist Orthodontist and Lecturer of Orthodontics (Malta)
Dr. Dalia El-Bokle/ Specialist Orthodontist and Professor in Orthodontics (Egypt)
Dr Rim Fathalla/ Specialist Orthodontist (Egypt)
Dr. Lubna Almuzian/ Specialist Paediatric Dentist (UK)
Dr. Ahmed El-Shanawany/ Specialist Orthodontist (Egypt/ UK)
Dr. Lina Sholi/ Specialist Orthodontist (KSA/ Turkey)
Dr. Ahmed M. A. Mohamed/ Specialist Orthodontist (Jordan/ UK)
Dr. Syed A. A. Bukhari/ Specialist Orthodontist (India/ KSA)
Dr. Muhammad Q. Saeed/ Professor in Orthodontics (Pakistan)
Dr. Asma R. Chaudhry/ Assistant Professor in Orthodontics (Pakistan)
Dr. Taimoor Khan/ Specialist Orthodontist (Pakistan)
Dr. Maham Munir/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Eesha Najam/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Abbas Naseem/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Amna S. Noor/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Hafiz M. Z. Majeed/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Hassan Saeed/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Maham Batool/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Eesha Muneeb/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Awrisha Tariq/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Hajira Arham/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Ayesha Tariq/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Farhana Umer/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Aroosh Ahmed/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Maha Arooj/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Khaula Ashfaq/ Postgraduate Trainee in Orthodontics (Pakistan)
Dr. Ayesha Iqbal/ House Officer/ CMH IOD LMC (Pakistan)

Acknowledgments
This book is the sum and distillate of work that would not have been possible without the support of our families
and friends. Special thanks to the contributors who continuously provided advice in developing this book and
up-dating individual chapters.
Finally, we acknowledge the hard work and expertise of Ms Faiza Umer Hayat who was responsible for compiling
this volume.

Copyrights
All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or
by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior
written permission of Dr Mohammed Almuzian and Dr Haris Khan who have the exclusive copyright, except in
the case of brief quotations embodied in critical reviews and certain other non-commercial uses permitted by
copyright law. For permission requests, contact them at info@orthodonticacademy.co.uk
ISBN-13 : 979-8428271911
ASIN : B09TYM7D4Z

Preface
Questions expose our uncertainty, and uncertainty has been our motive. The authors and contributors have ag-
gregated this book, and the series of books to follow, in answer to questions covering the breadth and depths of
orthodontics. This volume covers an orthodontic examination, anchorage, space planning and variants of maloc-
clusions including sagittal, transverse, vertical and local problems. Befittingly the theme of this chapter is Mars
to represent the importance of this volume.
The writing of the book started with the amalgamation of orthodontic notes and the experience of the main two
authors, Dr Mohammed Almuzian and Dr Haris Khan. The other authors helped in proofreading, summarising
the key points in a form of the ‘exam night re-view’. There have been numerous contributors to this book, as
co-writers of specific chapters or as proofreaders, we seek to acknowledge them. To give credit where it is due,
the role of the authors and contributors of this volume are listed on the title page of each individual chapter.

Table of Contents
Facial, smile and dental analysis.......................... 1
Facial analysis (macro-aesthetics) ...................................2
Are CFA parameters standard?............................................2
Importance of CFA................................................................2
Methods of CFA.....................................................................2
Steps in CFA...........................................................................3
Frontal facial analysis............................................................3
Transverse analysis from frontal view.................................4
Aetiologies of lip incompetency .........................................5
Profile analysis........................................................................5
2. Analysis of the high midface............................................5
3. Analysis of the maxillary area..........................................5
5. Analysis of the mandibular area......................................6
Smile analysis (mini-aesthetics) and its components.......6
2. Gingival Heights, Shape and Contour ......................7
3. Connectors..........................................................................7
5. Tooth Shade and Color.....................................................7
Imaging In Orthodontics: Radiography &
Photography......................................................... 13
Goals of imaging....................................................................14
Classification of imaging techniques .................................14
Radiographic imaging techniques ......................................14
Key aspects of IRMER 2000..................................................14
X-Ray variables.......................................................................14
Measurements of radiation doses ......................................14
Image receptors ....................................................................16
Setting the chair-side dental X-ray equipment..................16
Occlusal radiographs.............................................................16
Periapical radiographs...........................................................16
Bitewing radiographs.............................................................16
Orthopanoramic radiography (OPG).................................16
Lateral cephalogram..............................................................17
Types of errors in cephalometric analysis...........................18
Projection error......................................................................18
Maxillary skeletal and dental changes.................................19
Mandibular skeletal and dental changes.............................19
Template analyses ..................................................................19
Pitchfork analysis...................................................................19
Pancherz analysis...................................................................19
Bolton template analysis.......................................................19
3D cephalometric superimpositions ..................................19
Computed tomography (C.T.)..............................................19
Frontal cephalometry/ posteroanterior radiographs.........21
Hand or wrist radiographs....................................................21
Radionuclide imaging...........................................................21
Requirement of digital photography ..................................21
Intraoral scanning (oral scanner) ......................................22
Types of intraoral imaging techniques................................22
3D digital study models........................................................23
Stereophotogrammetry.........................................................23
Laser scanning........................................................................23
Optical surface scanning.......................................................24
Structured light imaging.......................................................24
Magnetic resonance imaging and orthodontics................24
Cephalometric In Orthodontics.......................... 31
History.....................................................................................32
Equipments.............................................................................32
Clinical stages in taking a cephalogram..............................32
Uses of cephalometry ...........................................................32
Requirements of cephalometric measurement..................33
Common cephalometric landmarks....................................33
Cephalometric lines for skeletal analysis............................33
Cephalometric lines for dental analysis..............................34
Cephalometric measurements for profile analysis............34
Cephalometric measurements for lip analysis...................34
Cephalometric measurement for labionasal analysis........35
Cephalometric measurement for labio-mental analysis...35
Cephalometric analysis techniques.....................................35
Key cephalometric analysis ..................................................35
Mills’ Eastman correction (Mills, 1970)..............................38
Limitations of the Eastman correction ..............................38
Limitations of Steiner analysis.............................................39
Space Analysis In Orthodontics........................... 43
Clinical application of space analysis..................................44
Advantages and disadvantages of RLSA ............................46
Other Methods for Space Analysis in Permanent
Dentition.................................................................................46
Symmetry of the Arch...........................................................47

Bolton analysis........................................................................47
Bolton ratios, malocclusion and gender ............................48
Bolton ratios and ethnic groups...........................................48
Exam Night Review...............................................................48
Orthodontic Indices............................................. 51
Ideal characteristics of an index...........................................52
Types of indices......................................................................52
Other criteria of the DHC.....................................................56
Aesthetic Component (AC)..................................................56
Index of Orthognathic Functional Treatment Need
(IOFTN)..................................................................................56
Advantages and disadvantages of the IOTN......................56
Peer Assessment Rating (PAR).............................................57
Anterior segments ...............................................................57
.................................................................................................58
Buccal occlusion.....................................................................59
Table 11: Buccal occlusion assessment ...............................59
Overjet.....................................................................................59
Centerlines..............................................................................59
Advantages of PAR index .....................................................60
Disadvantages of PAR index.................................................60
Outcome assessment of PAR................................................60
Index Of Complexity Outcome & Need (ICON)..............60
Table 16: Interpretation of ICON scores.............................60
American Board of Orthodontics Discrepancy
Index (ABO DI) ....................................................................61
Crowding.................................................................................62
Buccal Occlusion....................................................................62
Cephalometric analysis.........................................................63
Advantages of ABO DI..........................................................63
Disadvantages of ABO DI.....................................................63
Handicapping malocclusion assessment record ...............63
Little irregularity (LI) index.................................................63
Crowding index ....................................................................63
Maxillary expansion indices ................................................64
Treatment difﬁculty index for unerupted maxillary
canines ....................................................................................64
Plaque index ..........................................................................64
Calculation of plaque index .................................................64
Gingival index (GI)................................................................64
Basic Periodontal Examination (BPE)................................64
Helkimo Clinical Dysfunction (HCD) Index....................65
GOSLON index......................................................................65
Tooth Wear Index..................................................................65
Root resorption indices ........................................................65
Maxillary suture fusion index..............................................67
Mid-palatal suture density ratio (MSDR) ..........................67
Five stage midpalatal suture maturation method..............67
EXAM NIGHT REVIEW.....................................................67
Orthodontic Anchorage....................................... 71
Intra-oral sources of OA.......................................................72
Extra-oral sources of OA......................................................72
Terms and principles used with OA....................................72
Classification of OA...............................................................72
Supplementing the OA unit..................................................73
OA in three planes.................................................................74
Assessment of OA need.........................................................74
TEMPORARY ANCHORAGE DEVICES ........... 79
A brief history of TADs.........................................................80
Design features of TADs ...................................................80
These include:.........................................................................80
Characteristics for ideal TADs.............................................80
These include:.........................................................................80
Osseointegrating screws........................................................80
Types of osseointegrating screws.........................................80
These include:.........................................................................80
Mechanically retained screws...............................................81
Types of mechanically retained screws...............................81
Stability & failure of mini-screws.........................................82
Factors affecting failure of miniscrews ...............................83
The failure rate of miniscrews according to the site
of insertion .............................................................................83
Special features in the miniscrews.......................................83
How to optimise the success rate of miniscrews?..............84
Post-operative instructions...................................................84
Direct Vs indirect anchorage ...............................................84
Bicortical anchorage..............................................................85
Complications associated with TADs..................................85
Exam night review.................................................................85
Extraction in orthodontics .................................. 91

Why do we take teeth out?....................................................92
Claimed advantages of the non-extraction approach ....92
Claimed advantages of extraction approach ...................92
Prevalence of extractions in orthodontics..........................92
Evidence about the detrimental effects of extraction........92
Extraction of Specific teeth...................................................93
Extraction of primary teeth..................................................93
Guidelines for extraction of primary teeth.........................94
Extraction of permanent teeth.............................................94
Contraindications for lower incisor extraction..................94
Problems associated with lower incisor extractions..........94
2. Lower canine extraction....................................................95
3. Lower first premolars extraction......................................95
4. Lower second premolars extraction................................95
5. Lower first molar extraction.............................................95
Contraindications for first molar extraction......................95
6. Lower second molar extraction.......................................95
Contraindications for second molar extraction.................96
Advantages of second molar extraction..............................96
7. Upper central incisor extraction......................................96
8. Upper lateral incisor extraction.......................................96
Contraindications for for upper lateral incisor
extraction................................................................................96
9. Upper canine extraction...................................................96
10. Upper first premolars extraction...................................96
11. Upper second premolar extraction................................97
12. Upper first molar extraction...........................................97
13. Upper second molar extraction.....................................97
Third molars extraction........................................................97
Interproximal Enamel Reduction ....................... 103
Indications of IPR..................................................................104
General advice before commencing IPR procedure ........104
Methods of IPR .....................................................................104
Air rotor stripping (ARS)......................................................105
Long term potential side effects of IPR...............................105
Interproximal Enamel Reduction........................................105
CLASS 1 MALOCCLUSION................................ 109
Aetiologies of Class I malocclusion.....................................110
Extra-oral features of Class I malocclusion........................110
Intra-oral features of Class I malocclusion.........................110
Methods of space provision to treat Class I
malocclusion...........................................................................110
Bimaxillary Proclination...................................... 113
Aetiologies of bimaxillary proclination..............................114
Classification of bimaxillary proclination..........................114
Features of bimaxillary proclination...................................114
Treatment of bimaxillary proclination................................115
Treatment considerations while managing bimaxillary
proclination............................................................................115
Relapse after treating bimaxillary dentoalveolar
proclination............................................................................115
Class II Division 1 Malocclusion ........................ 119
Incidence of Class II Division 1 malocclusion ..................120
Aetiology of Class II Division 1 malocclusion...................120
Features of Class II Division 1 malocclusion ....................120
Type of lip behaviour to achieve anterior oral seal in
patients with Class II malocclusion.....................................121
Justifications for early treatment of Class II
malocclusions .....................................................................121
Treatment timing for Class II Division 1 malocclusion....121
Growth modification / functional jaw orthopaedics
to treat Class II Division 1 malocclusion............................121
Effects of Class II functional appliances.............................121
The proposed advantages of the phase I intervention ......121
Disadvantages of phase I intervention ..............................122
Effectiveness of phase I intervention .................................122
Orthodontics camouflage to treat Class II Division 1 maloc-
clusion.....................................................................................122
Orthodontics camouflage treatment modalities to treat
Class II Division 1 malocclusion..........................................122
Favourable features for orthodontics camouflage.............122
Combined orthodontic-surgical approach.........................122
Indicators for orthognathic surgery....................................122
Aetiology of relapse of the treated Class II Division 1
malocclusion..........................................................................123
Enhancing the stability of treated Class II Division 1
malocclusions........................................................................123

Class II Division 2 malocclusion ........................ 127
Classification of Class II Division 2 malocclusion ............128
Incidence of Class II Division 2 malocclusion...................128
Aetiology of Class II Division 2 malocclusion...................128
Features of Class II Division 2 incisor relationships.........128
Justification for treatment.....................................................129
Treatment aims.......................................................................129
Treatment options..................................................................129
Timing of treatment..............................................................129
Stability and retention...........................................................130
Proclination of lower incisors in Class II Division 2
cases.........................................................................................130
Long-term retention plans ...................................................130
Class III Malocclusion.......................................... 133
Classification of Class III malocclusion..............................134
Classification Class III malocclusion based on the
severity ....................................................................................134
Prevalence of Class III malocclusion...................................134
Aetiologies of Class III malocclusion..................................134
Clinical features of Class III malocclusion.........................134
Treatment options for Class III malocclusion....................135
Interceptive treatment...........................................................135
Growth Modification.............................................................136
1. Protraction Facemask (PFM).........................................136
2. Chin cup therapy.............................................................136
3. The Frankel III (FR-3) appliance...................................136
4. Bone anchored maxillary protraction/Bollard
plates (BAMP).......................................................................136
Orthodontic camouflage treatment.....................................136
Favourable features for orthodontic camouflage .............137
Guidelines for orthodontic camouflage..............................137
Consideration of a single lower incisor extraction............137
Bracket prescription can aid camouflage of the
Class III malocclusion...........................................................137
Dental decompensation and orthognathic surgery...........137
Transverse arch discrepancY................................ 141
Different terminologies in transverse maxillary
deficiency ...............................................................................142
Types of maxillary skeletal deficiency.................................142
Benefits of treating displacement ........................................142
Incidence of transverse maxillary deficiency.....................143
Age-related changes in maxillary dimension.....................143
Aetiologies of transverse maxillary deficiency...................143
Clinical features of transverse maxillary deficiency..........143
Diagnosis of transverse maxillary deficiency.....................143
CBCT evaluation....................................................................144
Treatment objectives .............................................................144
How much expansion is required? .....................................144
Non-surgical maxillary expansion ......................................144
Advantages of Quadhelix appliance....................................145
Disadvantages of Quadhelix appliance...............................145
Principle of RME....................................................................145
The rationale for expansion treatment................................145
Types of conventional RME..................................................146
The influence of the height of RME ....................................146
Proposed indications of the RME........................................146
Contraindications and limitations of conventional
RME.........................................................................................147
Potential complications of RME..........................................147
Mid-palatal suture assessment methods.............................147
Mid-palatal suture maturation classification .....................147
Interpretation mid-palatal suture maturation classification:
147
Mid-palatal suture density ratio ..........................................148
Protocols of maxillary expansion .......................................148
Surgical maxillary expansion...............................................149
1. Surgically assisted RME (SARME or SARPE).............149
Indications for SARPE ..........................................................149
Complications during SARPE..............................................149
2. Multiple piece maxillary osteotomy (MPMO) ............149
Retention and stability secondary to MPMO....................149
Factors & Yardsticks ............................................................150
Appliances for unilateral maxillary expansion..................150
Treatment of scissor bite.......................................................150
Stability and retention of expansion....................................150
Anterior crossbites.................................................................150
Requirement for the successful results using URA...........150
Dental & Skeletal Asymmetries........................... 157

Prevalence of dental & skeletal asymmetries ....................158
Aetiology of dental & skeletal asymmetries.......................158
Classification of dental & skeletal asymmetries.................158
Overview of different types of asymmetry ........................158
Traumatic asymmetry...........................................................159
Hemifacial microsomia (HFM)...........................................159
Clinical features of HFM.......................................................159
Types of HFM.........................................................................159
Classification of HFM ..........................................................159
Juvenile Rheumatoid Arthritis (JRA)..................................159
Treatment of Juvenile Rheumatoid Arthritis.....................160
Idiopathic condylar resorption (ICR) ...............................160
Torticollis (Wry Neck)...........................................................160
Hemifacial hypertrophy........................................................160
Hemifacial atrophy (Parry-Romberg syndrome)..............160
Asymmetric mandibular excess...........................................160
Management of asymmetric mandibular excess................161
Mandibular displacements on closure................................162
Dental asymmetries...............................................................162
Causes of dental midline asymmetry..................................162
Class II subdivision................................................................162
Class III subdivisions.............................................................162
Management of functional asymmetry...............................164
Management of skeletal asymmetry....................................164
High Angle Cases................................................. 169
Aetiology of high angle cases...............................................170
Clinical features of high angle cases....................................170
Radiographical features.........................................................170
Clinical implications in treating high angle.......................170
Treatment considerations.....................................................170
Anterior open bite................................................ 173
Aetiology of AOB...................................................................174
Classification of AOB............................................................174
Incidence of AOB...................................................................174
Predictors of skeletal open bite............................................175
Features of skeletal open bite................................................175
Aetiology of AOB...................................................................176
Digit Sucking Habit...............................................................178
Long term effects of pacifier and dummy sucking
habit.........................................................................................178
Management of digit-sucking habits .................................179
Types of removable habit breakers .....................................179
Types of fixed habit breakers .............................................179
Summary of evidence ..........................................................179
Management of mouth breathing........................................180
Management of secondary tongue thrust...........................180
Myofunctional therapy for the treatment of AOB.............180
Combined myofunctional and extraoral appliance
combination therapy.............................................................182
Extraoral appliance for management of AOB....................182
Treatment principles in the management of AOB
using fixed appliances............................................................183
Kim mechanics.......................................................................183
Modified Kim mechanics......................................................184
Molar intrusion using skeletal anchorage...........................184
Treatment considerations of AOB treated with molar
intrusion .................................................................................184
Rapid molar intrusion device (RMI)...................................185
Advantages and disadvantages of RMI...............................185
Repelling magnets for the treatment of OAB.....................185
Orthognathic option for management of skeletal
AOB.........................................................................................186
Factors contributing to skeletal relapse .............................186
Adjunctive procedures..........................................................186
Stability of AOB treatment...................................................186
Causes of relapse of treated AOB cases...............................187
Retention of treated AOB cases............................................187
Methods for retention...........................................................187
Difficulty associated with the treatment of AOB ..............188
Posterior open bite.................................................................188
Causes of posterior open bite...............................................188
Treatment of posterior open bite.........................................188
Exam night review................................................................188
Deep bite .............................................................. 199
Basic terminologies................................................................200
Aetiology deep overbite.........................................................200
Principles of deep incisor overbite reduction.....................200
Consideration factors for the method of treating DOB....200
These include:.........................................................................200
Management of overbite .....................................................201

Methods to reduce the unwanted labial tipping of lower
incisors during levelling .....................................................201
Advantages of segmental archwires technique ..................202
Disadvantages of segmental mechanics..............................202
Effectiveness of different approaches...................................202
References.........................................................................................203
Low Angle Cases................................................... 206
Aetiology of low angle cases.................................................207
Features of low angle cases...................................................207
Principals of treatment .........................................................207
Methods to reduce overbite ................................................207
The Dahl concept...................................................................208
Hypodontia........................................................... 210
Classification of hypodontia ................................................211
Candidate genes ....................................................................211
Incidence of hypodontia ......................................................211
Aetiology and theories of hypodontia ................................212
Clinical presentation of hypodontia ...................................213
Malocclusion features of hypodontia patients ..................213
Indications for treatment .....................................................213
General treatment principles................................................213
Options for treatment ...........................................................214
These include (Gill and Barker, 2015):................................214
Advantages of auto-transplantation (Aslan et al., 2010)...215
Problems and solutions of cuspid substitution..................215
Benefits of cuspid substitution.............................................215
.................................................................................................217
Compensated axial tip of brackets for space closure
treatment option...................................................................219
Camouflaging the size and shape of teeth for space
closure treatment option.......................................................219
E. Reopen or redistribute space.........................................219
Space opening and prosthetic replacement........................220
Types of final restorations.....................................................220
Criteria for implant placement ...........................................220
Success of dental implants....................................................220
Treatment options for absent premolars.............................221
Evidence summary................................................................221
Supernumerary Teeth .......................................... 228
Incidence of supernumerary teeth.......................................229
Aetiology of supernumerary teeth.......................................229
Genetic influences in the development of
supernumerary teeth.............................................................229
Clinical features and effects of supernumerary teeth ......230
Classification of supernumerary teeth................................230
Examination of supernumerary tooth................................230
Management of supernumerary tooth................................231
Detailed management of each type of supernumerary ...231
Conical supernumerary ......................................................231
The effect of conical supernumerary on permanent
incisors are:............................................................................231
Tuberculate supernumerary.................................................231
Supplemental supernumerary teeth....................................232
Odontomes supernumerary ................................................232
..................................................................................................
232
Evidence summary................................................................232
Impacted Maxillary Central Incisor.................... 236
Incidence of unerupted central incisor...............................237
Aetiology of unerupted central incisor...............................237
Effects of unerupted central incisor.....................................237
Diagnosis of unerupted central incisor...............................237
Considerations during treatment planning ......................238
The correlation between dilacerated and impaction
of incisors................................................................................238
Types of tooth dilacerations.................................................238
Methods for space creation to allow spontaneous
eruption..................................................................................238
Extraction/removal of physical obstruction.......................239
Watchful waiting or mechanical traction?..........................239
Closed surgical exposure techniques .................................239
Open versus closed exposure (eruption) techniques........240
Surgical extraction of the impacted incisor and
coronectomy ..........................................................................240
Surgical extraction or auto-transplantation.......................240
Advantages of autotransplantation......................................240
Risks and disadvantages of autotransplantation ...............240
Factors affecting the success of autotransplantation.........240

Success rate of autotransplantation ....................................240
Prognosis of autotransplantation ........................................241
Management of ankylosed maxillary incisors....................241
Impacted Canine.................................................. 247
Prevalence and Incidence.....................................................248
Development and eruption of maxillary canines..............248
Aetiology of impacted canines.............................................248
Recent classification of aetiology of maxillary canine
impaction...............................................................................248
These include (Becker and Chaushu, 2015):......................248
Theories of palatally impacted canines...............................249
Classification of impacted maxillary canines ...................249
These include:.........................................................................249
Investigations and diagnosis ...............................................250
Magnification technique.......................................................250
Parallax Technique.................................................................250
Ericson and Kurol sectors’ classification as predictors of
severity of impacted canine .................................................251
Four sector classification by Lindauer ...............................251
These include:.........................................................................251
The three-sector classification by Dr Crescini...................251
Sector classification by Stivaros and Mandall ..................251
Alpha angle as predictors of severity of impacted canine.251
β- and Gamma angle as predictors of severity of
impacted canine.....................................................................251
Distance of the canine’s crown from the occlusal plane as
predictors of severity of impacted canine...........................252
Position of canine root apex anteroposteriorly as
predictors of severity of impacted canine...........................252
Incidence of root resorption (RR) ......................................252
Risk factors for resorption of lateral roots..........................252
Management and treatment options for impacted
canines ...................................................................................252
Indication for no active treatment.......................................253
Interceptive treatment...........................................................253
Guidelines for interceptive extraction of deciduous
canine......................................................................................253
b. Other interceptive techniques for impacted or
displayed canine ....................................................................253
Surgical exposure and orthodontic alignment...................254
Type of surgical exposure ....................................................254
Open exposure.......................................................................254
Advantages of open exposure...............................................254
Disadvantages of open exposure..........................................254
Closed surgical exposure......................................................254
Advantages of closed exposure............................................255
Disadvantages of closed exposure.......................................255
Crescini’s tunnel technique ..................................................255
Choices of surgical exposure................................................255
Mechanical eruption of the impacted canine.....................256
Indications for surgical removal of the palatally ectopic
permanent canine..................................................................256
Indication of transalveolar autotransplant.........................257
Indication of surgical repositioning ...................................257
Causes of poor outcome ......................................................257
Impacted mandibular canine...............................................257
Exam Night Review...............................................................258
Primary Failure Of Eruptions.............................. 263
.............................................................................. 263
Classification of failure of eruption ....................................264
Incidence of PFE....................................................................264
Aetiology of PFE....................................................................264
Features of PFE ......................................................................264
Treatment options of the PFEc.............................................264
Aetiology of the mechanical failure of eruption ..............264
Transposition of teeth ......................................... 267
Types of transposition...........................................................268
Aetiology of transposition....................................................268
Prevalence of transposition..................................................268
Classification .........................................................................268
Maxillary canine and the first premolar (Mx.C.P1) .........268
Factors affecting treatment decision ..................................269
These include: ........................................................................269
Maxillary canine-lateral incisor transposition ..................269
Maxillary canine-first molar transposition (Mx.C.M1)....269
Maxillary incisors transposition (Mx.I2.I1).......................269
Maxillary canine central incisor transposition..................269
Mandibular canine lateral incisor transposition ...............269
Mandibular canine central incisor transposition .............269

Intraosseous migration.........................................................269
Aetiology of intraosseous migration .................................269
Clinical signs of intraosseous migration.............................269
Mupparapu classification for transmigrated mandibular ca-
nine..........................................................................................270
Third molar and its impaction............................. 273
Prevalence of third molar impaction and hypodontia......274
Aetiology of third molar impaction....................................274
Classification of third molar impaction..............................274
Lower incisor crowding and third molar debate...............274
Research recommendations .................................................274

1
1. Facial analysis (macro-aesthetics)
2. Are CFA parameters standard?
3. Importance of CFA
4. Unattractive features of facial appearance
5. Common landmarks used in facial anthropom-
etry diagram needed
6. Steps in CFA
7. Frontal facial analysis
8. Transverse analysis of the frontal view
9. Profile analysis
10. Analysis of the high midface
11. Analysis of the maxillary area
12. Analysis of the mandibular area
13. Smile analysis (mini-aesthetics)
14. Dental appearance (micro-aesthetics)
15. Gingival heights, shape and contour
16. Connectors
17. Embrasures: black triangles
18. Method to treat black triangle
19. Tooth shade and color
20. Teeth size and space analysis
21. EXAM NIGHT REVIEW
In this Chapter
Facial, smile and dental
analysis
Written by: Mohammed Almuzian, Haris Khan, Farhana Umer

Facial, Smile And Dental Analysis
2
Facial analysis (macro-aesthetics)
Clinical facial analysis (CFA) is a method utilised by the cli-
nician to evaluate and judge the patient ‘s face; to define its
proportions, volume, appearance, symmetry, and visible de-
formities (Meneghini and Biondi, 2012). Facial aesthetics is
considered a term used to describe the quality of beauty and
acceptance.
Are CFA parameters standard?
One of the aims of CFA is to assess the facial aesthetics of the
patient. There are many factors that affect the values during
CFA steps, which include:
• Racial background.
• Cultural difference.
• Gender.
• Personal preference.
• Clinician philosophy.
Importance of CFA
McLaughlin and Arnett (Arnett, 2004) in their textbook ‘’Fa-
cial and Dental Planning for Orthodontist & Oral Surgeon’’
classify the dentofacial deformities in the adult patient into
3 groups (G):
• G1 which can be addressed comprehensively by routine
orthodontic treatment
• G2 represents a deformity with mild to moderate skel-
etal discrepancies but can be well treated by some dental
compensation to achieve camouflage results
• G3 represents cases with severe facial imbalance and
malocclusion, which should be treated by combined sur-
gery and orthodontics.
It is inappropriate to provide the treatment modalities of G3
to G2 without making a comprehensive facial diagnosis. So,
differentiation between these two groups is considered one of
the main criteria for treatment success. The way of differenti-
ating between the two groups mainly depends on the evalua-
tion and assessment of the diagnostic records; among these is
the clinical facial analysis (CFA).
To sum up, the main objectives of CFA are:
• To diagnose and classify the deformities especially for
borderline cases.
• To plan the treatment approach that addresses the pa-
tient concerns and complaints.
• To predict the treatment outcomes & prognosis.
Unattractive facial features
The following features of facial appearance are generally rated
as unattractive:
• Little show of vermilion border
• A very high or very low smile line
• An upper lip that slopes backward
• An everted lower lip
• Extreme bilabial protrusion
• Lack of a well-defined labiomental fold
• Severe convex or concave profile
To whom CFA might be beneficial?
These include:
• Restorative dentist.
• Maxillofacial surgeons.
• Orthodontists.
• Plastic surgeons.
• Ophthalmic surgeons.
• ENT surgeon.
• Rehabilitative dentists.
• Dermatologists.
• Non-medical professionals such as hairdressers, eye-
glasses designers and make-up artists.
When should CFA be performed?
Initial CFA usually starts during the observation stage, from
the time of patient entrance to the clinical practice. It can also
be performed during the questionnaire stage. The clinician
should have the skill of interpreting and understanding body
language. However, comprehensive CFA is usually undertak-
en during clinical examination stage (Meneghini and Biondi,
2012)
Methods of CFA
These include:
• Direct clinical examination
• Non-radiographical imaging methods (Clinical photo-
graphs).
• 3D photography
Common Landmarks used in Facial Anthropometry
These include:
• Alar curvature (Ac): The most lateral point on the
curved base line of each ala, indicating the facial inser-
tion of the nasal wingbase.
• Cheilion (Ch): The point located at each labial commis-
sure.

Facial, Smile And Dental Analysis 3
• Crista philtre (Cphi): The peak of Cupid’s bow of the
upper lip inferior.
• Endocanthion (Enc): The point at the inner commissure
of the eye fissure, located lateral to the bony landmark.
• Exocanthion (Excellence): The point at the outer com-
missure of the eye fissure, located slightly medial to bony
exocanthion.
• Inferior Labrale Superius (ILs): A landmark on the up-
per lip located midway between Labrale Superius and
Stomion Superius.
• Labrale inferius (Li): A point indicating the muco-cuta-
neous border of the lower lip.
• Labrale superius (Ls): A point indicating the muco-cu-
taneous junction of the upper lip and philtrum.
• Soft tissue Nasion (N): The point in the midline of both
the nasal root and the nasofrontal suture, always above
the line that connects the two inner canthi, identical to
bony nasion.
• Soft tissue Pogonion (Pog): The most anterior midpoint
of the chin, located on the skin surface in front of the
identical bony landmark of the mandible.
• Pronasale (Prn): The most protruded point of the apex
nose identified in lateral view of the rest position of the
head.
• Soft tissue A point: The deepest midline point on the
upper lip, which is located usually halfway between Sn
and Ls.
• Soft tissue B point: The deepest midline point on the
labiomental fold, which determines the lower border of
the lower lip or the upper border of the chin.
• Subnasale (Sn): The midpoint of the angle at the colu-
mella base where the lower border of the nasal septum
and surface of the upper lip meet.
• Subtragion (Sbtr): The most anterior inferior point on
the anterior inferior margin of the helix attachment to
the face, just above the earlobe. It is different from Porion
• Superior Labrale Inferius (SLi): A landmark on the
lower lip located midway between Stomion Inferius and
Labrale Inferius.
Steps in CFA
These include:
1. Positioning the patient in a Natural Head Position
(NHP). NHP was developed by Moorrees (MOORREES,
1958). It is performed by asking the patient to walk into
the room for a few minutes to relax, then looking at a
mirror located at a distance 5 feet away, shake the head
until a comfortable position is achieved (Solow and Tall-
gren, 1971). NHP has 2° reproducibility (Cooke and Wei,
1988, Lundström and Lundström, 1992).
2. Teeth should be in centric relation with first tooth con-
tact. Sometimes the use of a precentric wax bite is es-
sential when there is more than 1mm difference between
the retruded contact position (RCP) and the intercuspal
position (ICP). If the wax bite cannot be obtained with
the condyle in the RCP due to adaptive changes, it is rec-
ommended to use a deprogramming splint (Arnett and
Gunson, 2004, Arnett, 2004).
3. Lips should be in a relaxed position especially in case of
vertical deficiency that resulted in soft tissue deformity
in centric occlusion.
4. Undertaking a stepwise CFA in three planes of space.
Frontal and profile analysis, this should not be under
emphasized since the major concerns of the patient are
those that are visible viewed from the frontal aspect.
45-degree analysis is recommended to deeply investigate
some features that cannot be fully assessed by frontal and
profile view. Other views for CFA including face base
(bird eye view), face down or worm view (submental),
nasal base view (subnasal).
Frontal facial analysis
A. Facial type analysis from frontal view
Facial type represents the ratio between the facial height
(Trichion-Menton or Tr-Me) and width (Zygion-Zygion or
Zy-Zy)= (Facial index). The bizygomatic facial width is mea-
sured from the most lateral point of the soft tissue overlying
each zygomatic arch (zygion), and is approximately 70% of
vertical facial height. Bitemporal width is measured from the
most lateral point on each side of the forehead, and is 60 %
of vertical facial height. While the bigonial width is measured
from the soft tissue overlying the most lateral point of each
mandibular angle (soft tissue gonion), and is usually 50% of
vertical facial height.
There are three facial types, long, short and square face. The
proportionate facial height to width ratio is 1.35:1 for males
and 1.3:1 for females (Naini and Gill, 2008).
B. Vertical facial heights analysis from frontal view
It is important to consider the vertical facial proportions and
their balance in relation to the patient’s general build and
personality. Ricketts (Ricketts, 1979) divided the face using
the middle and lower facial heights only. While Bell and Fish
(Bell, 1980, Fish and Epker, 1980) divided the face into three
facial thirds (62-75 mm each) as below:
• Upper third, from hairline (trichion) to glabella or
mid-brow.
• Middle third, from glabella to subnasale,
• Lower third, from subnasale to soft tissue menton.

4
Facial thirds should be equal to each other, however, the
underlying cephalometric proportions of the middle to the
lower facial height are not equal (45:55). This is because the
N, ANS, and Me points in cephalometrics are used instead of
Glabella, soft tissue Nasion, and soft tissue Menton used in
soft tissue analysis.
The lower anterior facial third is further subdivided
into (Farkas et al., 1985):
• Upper lip segment from subnasale to stomodi-
on superioris which is 19-22mm on average, higher
in male than female and decreases with aging.
• Lower lip and chin segment from stomodion
inferioris to soft tissue Menton which is 42-48mm
on average. The height of this segment increases
with age due to submental fat accumulation. Lower
lip and chin segment can be subdivided equally into
the lower lip region, from stomodion inferioris to
soft tissue B point, and the chin region, from soft
tissue B point to soft tissue soft tissue Menton.
• Interlabial gap that extends from stomodion
inferioris to stomodion superioris. On average,
it is 1-5mm and it is larger in females than males
because males have a longer upper lip.
Vertical maxillary excess (VME)
The main features are:
• VME is asscoiated with and increase in the anterior low-
er facial height.
• VME results from excessive inferior development of the
maxilla.
• VME is often accompanied by excessive gingival display
at rest and on smiling, referred to as a ‘gummy smile’.
• VME can be accompanied by an increased vertical chin
length, increased AFH and posterior mandibular rota-
tion secondary to over eruption of the posterior teeth.
3. Transverse analysis from frontal view
These include:
A. Facial symmetry assessment cab be performed using:
• Facial midline which is represented by a perpen-
dicular line from glabella to the interpupillary
line or to true horizontal line if the pupils are not
leveled. Alternatively, the middle of the philtrum
of the upper lip (Cupid’s bow) and glabella (Naini
and Gill, 2008) or center of the nasal bridge (Arnett,
2004) are used to construct the facial midline. If the
nasal deviation is significant, the philtrum might be
deviated, and the use of vertical perpendicular from
glabella might be used as an alternative (Sheen and
Sheen, 1987). Postural camouflage can be a problem
in asymmetrical faces as patients with a marked
occlusal cant habitually tilt the head to level the lip
line giving the impression of orbital dystopia. This
is usually corrected by bimaxillary leveling of the
occlusal plane.
• Rule of fifths in which each fifth is approximately
the width of an eye, the mouth width is equal to the
distance between the medial iris margins (65mm)
while the alar base width is equal to the intercanthal
distance (34mm).
B. Skeletal base assessment which includes:
• Mandibular assessment using chin-jaw imaginary
line which is a line under the surface of the chin
at maximum tissue contact. This imaginary line
should be parallel to the inter-pupillary line in the
absence of vertical orbital dystopia, otherwise, it is
described as cant.
• Mid-face and maxillary assessment to detect signs
of midface deficiency such as increased sclera show
above the lower eyelid, Class III problem, paranasal
hollowing, flattened upper lip, an obtuse nasolabial
angle, narrow upper arch with crossbite and crowd-
ing and wide buccal corridor.
C. Lip assessment which should be undertaken in the order
of the LAMP acronym (LAMP= Line, Activity, Morphol-
ogy, and Position of the lips).
i) Lip lines: Vertically, the lower lip should cover the
incisal third of maxillary incisors, while the upper
lip should cover the upper two thirds. Maxillary
incisor exposure at rest ranges from 2–4 mm, and it
depends on:
• Age.
• Lip activity during facial animation.
• Upper lip length.
• Clinical crown length.
• Anterior maxillary alveolar height.
• Maxillary incisor inclination.
• Combinations of the above.
If the upper lip length is very short, then, the patient would
be expected to show more of the upper incisors. Any attempt
to reduce the incisor exposure in relation to a short upper lip
will lead to an unaesthetic reduced middle face height. Simi-
larly, with a long upper lip, the patient would be expected to
show less or no upper incisor, both at rest and during facial
animation.
ii) Lip activity: A strap-like lower lip often retroclines
incisors and commonly presents in Class II division

2 malocclusions (Moss, 1975). Flaccid lips are less
likely to alter position with anteroposterior dental
movement significantly.
iii) Lip morphology: Vermilion show is normally
12mm and 9mm for lower and upper lip respec-
tively (Fish and Epker, 1980). The position of full
lips are less likely to be altered significantly with the
anteroposterior dental movement while thin lips are
more likely to ‘flatten’ with incisor retraction.
iv) Lip posture: Lip competency plays a role in the aeti-
ology of malocclusion and treatment stability. Types
of lip relationships are:
• Competent represents lips that are held to-
gether at rest.
• Habitually competent in which the lips are
held apart at rest by more than 3–4 mm, but the
patient tries to posture his/her jaw forward to
achieve anterior lip seal like in Class II division
1 cases.
• Potentially competent in which the lips are
unable to be held together due to increased in-
ter-labial space. The patient exerts muscle effort
to close them, which can be seen in the form of
an active mentalis muscle. The features of this
condition are puckering of the chin area and
flattening of the labiomental angle (LMA).
• Rolled blind upper lip means that the up-
per lip significantly retracts superiorly on smil-
ing resulting in increased gingival show.
Aetiologies of lip incompetency
These include:
• With aging, the lip incompetency is reduced.
• Reduced lip legnth.
• Increased lower anterior face height (LAFH) due to
VME.
• Increased LAFH due to posterior growth rotation.
• Over-eruption of the buccal segments.
• Anteroposterior skeletal malrelationships.
• Proclined upper labial segment or lower labial segment
(LLS).
D. Smile analysis (see section smile analysis/ mini-aesthet-
ics)
Profile analysis
1. Total soft tissue profile analysis
This can be undertaken using:
• Soft tissue nasion to Frankfurt horizontal: An easy
assessment of the relative protrusion of the mid third
and mandible can be made by assessing their position
relative to a perpendicular to the Frankfort plane pass-
ing downwards through soft tissue Nasion. With normal
facial proportions, the soft tissue profile of the maxilla
should be approximately 2-3 mm in front, and the soft
tissue pogonion should lie 2 mm behind this facial plane.
However, the face can vary with ethnic norms, giving an-
terognathic, mesognathic or posterognathic profiles.
• Angle of convexity (facial convexity) or profile angle:
Total facial angle is made by Glabella-subnasale-pog
(Burstone, 1958, Burstone, 1967). Class I occlusion cases
are usually present with a total facial angle that ranges
from 165-175 degrees, in comparison to a lower angle
(less than 165 degrees) in Class II cases and higher value
(higher than 175 degrees) in Class III cases (Arnett and
Bergman, 1993a, Arnett and Bergman, 1993b).
• Powell analysis (Powell and Humphreys, 1984): This
analysis is made up of nasofrontal angle 160°, nasofacial
angle 40°, and nasomental angle 160°.
• Steiner-Kole technique: It is used to determine the
dentofacial complex’s convexity by using SN-MP angle
which is 32°. In this analysis, the face can be classified
into divergent, convergent or normal. It is important
note that the cranial base orientation may vary and be
steeper in some instances.
2. Analysis of the high midface
• Soft tissue glabella should be 2mm ahead of the soft tis-
sue nasion
• Orbital rim should be 2mm posterior to the eye globe
(Fish and Epker, 1980).
• Cheek bone contour should be smoothly convex from
the eye’s outer canthus through the sub-pupil area to end
in the alar base (Fish and Epker, 1980).
• Morphology of the ears: If the external auditory meati
lie at unequal levels, this creates an asymmetrical facial
artifact.
3. Analysis of the maxillary area
These include:
• Nasal base assessment which can be undertaken using
vertical line from soft tissue Nasion perpendicular to
Frankfort horizontal (Zero Meridian line) or maxillary
plane (or ideally true horizontal line) with the patient in
NHP. Subnasale should be on this line (González-Ulloa

6
and Stevens, 1968).
• Nasal projection represents the distance from tip of the
nose to true vertical line (TVL). This distance is usually
22m.
• AP lip position that can be assessed using:
i) TVL: The upper lip normally touches the TVL
described by Arnett (Arnett et al., 1999).
ii) Esthetic line (E-line): E-line joins the nasal tip
to soft tissue Pogonion. The upper lip should be 4
mm behind this line in adults and it is very depen-
dent on nasal and chin projection (Ricketts, 1979).
iii) Steiner line (S-line): S-line joins soft tissue
pogonion to the midpoint (columella) between
Subnasale and nasal tip (pronasale). The lips should
touch this line.
iv) Harmony line (H-lines): H-lines was intro-
duced by Holdaway. The H-angle is formed by a line
tangent to the chin (Pog) and upper lip (Ls) with
the soft tissue N-Pog line. Holdaway said the ideal
face has an H-angle of 7° to 15°, which is dictated
by the patient’s skeletal convex¬ity. Normally, the
lower lip is located 0 to 0.5 mm anterior to the H
line.
4. Analysis of upper lip to nose relationship
This can be assessed using nasolabial angle which is formed
by the intersection of the upper lip anterior and columella at
Subnasale. The average value of this angle is 85°-120° (Fish
and Epker, 1980). It can be divided by true horizontal at Sub-
nasale point into two angles. The upper one represents nasal
angulation which is 28°, and the lower angle represents up-
per lip angulation which is 85°. An acute nasolabial angle is
an indication of a protrusive lip. An obtuse nasolabial angle
implies a retrusive upper lip or an upright nose. In general,
NLA depends on:
• Columella orientation.
• Anteroposterior position of maxillary incisors.
• Inclination of ULS.
• Anteroposterior position of the maxilla.
• The morphology of the upper lip.
• The vertical position of the nasal tip.
5. Analysis of the mandibular area
These include:
• Assessment of the AP lip position using TVL (lower lip
normally lies 0.5mm-2mm behind the TVL), E-line (the
lower lip lies 2 mm behind this line in adults) or S-line
(Both lips should touch this line).
• Lower lip to chin relationship is assessed using Labiomen-
tal angle (LMA) which is formed between the lower lip
and chin. The average value of this angle is 110°–130°.
LMA depends on thickness of lower lip, mental fat area,
prominence of the chin itself, AP skeletal relationship,
lower incisor inclination, anterior lower face height -and
lower lip to upper incisor relationship.
5. Anteroposterior chin position
• Bass aesthetic analysis (Bass, 2003): This
analysis uses Subnasale rather than soft tissue Na-
sion from which a perpendicular is dropped to the
true horizontal line with the patient in NHP. This
analysis is useful for planning treatment in man-
dibular retrognathia, where the maxillary position
is correct.
• Zero Meridian line: Vertical from soft tis-
sue Nasion, perpendicular to the true horizontal
line with the patient in NHP. Soft tissue Pogonion
should be 0 ± 2 mm to Meridian line.
• Holdaway angle: Formed between the Pog -lip
superioris line and N-Pog. The average value is 15°.
• Profile line or Z angle (of Merrifield). A tan-
gent to the chin and vermilion border of the most
prominent lip should ideally intersect with Frank-
fort horizontal at 80°+9° (Merrifield (Merrifield,
1966).
• Kole analysis which uses two lines, the first
from the prominent part of the upper lip perpen-
dicular to SN. While the other line extends from
Orbitale perpendicular to SN. The soft tissue Pog
should be in the middle of these two lines.
6. Relationship of chin to submental plane
• Lip-chin-submental plane angle: It has an value of 90–
110 °. Its value increases in cases with thick lower lip,
increased submental fat presence, mandibular retrog-
nathia, retrogenia, and lower lip projection due to pro-
clined LLS.
• Submental plane length: It represents the distance from
soft tissue menton to junction of submental plane and
vertical plane of the anterior aspect of the neck.
Smile analysis (mini-aesthetics) and its components
A. Smile arc: It is defined as the contour of the maxillary
anterior teeth incisal edges relative to the curvature of
the lower lip during a social smile. Ideally, the contour
of these teeth should match that of the lower lip. If the
lip and dental contours match, they are said to be conso-

nant. The lip to lower incisor relationship in determining
smile arc depends on a number of factors including:
• Soft tissue factors such as upper lip length and the ‘smile
curtain’ which is defined as the muscular capacity to
raise the upper lip.
• Skeletal factors such as the vertical position of the an-
terior maxilla (the more inferior the position of the an-
terior maxilla, the greater the exposure of the maxillary
incisors, and vice versa) and the anteroposterior position
of the anterior maxilla (the more anterior the position
of the anterior maxilla, the greater the exposure of the
maxillary incisors, and vice versa).
• Dental factors such as the vertical position of the incisor
teeth, the anteroposterior position of the incisor teeth,
the inclination of the maxillary incisor teeth (retroclina-
tion of proclined maxillary incisors towards the correct
inclination increases the incisor exposure), and maxil-
lary incisor crown length, including the presence of in-
cisal wear.
• Gingival factors such as the vertical level of the gingi-
val margins on the labial surface of the maxillary incisor
crowns.
B. Width of smile (Buccal corridor)
Buccal corridor is defined as the negative lateral space be-
tween the buccal surface of the distal-most maxillary molar
and the angle of the mouth on smiling. The ideal width of
buccal corridor is 11.5 (5-16 mm/17% total smile). Factors
affecting buccal corridor are:
• Arch form: A broad arch form will result in decreased
buccal corridors and vice versa.
• AP position of the maxilla: AP maxillary deficiency leads
to increased buccal corridors and an unaesthetic smile.
• Transverse maxillary deficiency which results in an in-
creased negative space.
• Palatally inclined maxillary posterior teeth.
• Wide commissure.
Dental Appearance (Micro-Esthetics)
1. Tooth Proportions
The apparent widths of the anterior maxillary teeth on smile,
and their actual mesio-distal width, differ because of the cur-
vature of the dental arch. Particularly, only a portion of the
canine crown can be seen in a frontal view. Ideally, the appar-
ent width of the lateral incisor (as one would perceive it from
a direct frontal examination should be 62% of the width of
the central incisor, the apparent width of the canine should
be 62% of that of the lateral incisor, and the apparent width of
the first premolar should be 62% of that of the canine.
2. Gingival Heights, Shape and Contour
Generally, the central incisor has the highest gingival level,
the lateral incisor is approximately 0.5 mm lower and the
canine gingival margin again is at the central incisor level. A
discrepancy in the gingival height may be due to periodon-
tal diseases, teeth attrition, ankylosis, severe crowding or
delayed maturation of gingivae.
3. Connectors
The connector includes the contact point and the areas above
it. The normal connector height is greatest between the cen-
tral incisors (50% of the height of teeth) and diminishes from
the central to the posterior teeth (ratio for central and lateral
incisor connector is 40% of central incisor height; ratio for
lateral incisor and canine connector is 30% of central incisor
height).
4. Embrasures and black triangles
The embrasures are triangular spaces gingival and incisal to
the connectors. The gingival embrasures are filled by the in-
terdental papillae. Short interdental papillae leave an open
gingival embrasure, also known as “black triangles”. Cur-
rent data indicates that lay detect open gingival embrasures
of 3 mm or more and judge them as unaesthetic (Kokich et
al., 1999). Black triangles in adults usually arise from loss of
gingival tissue and supporting bone related to periodontal
disease. When crowded and rotated maxillary incisors are
corrected orthodontically in adults, the connector moves in-
cisally and black triangles may appear. For that reason, both
actual and potential black triangles should be noted during
the orthodontic examination, and the patient should be pre-
pared for reshaping of the teeth to minimize this aesthetic
problem. The methods to minimise black triangle are:
• Interproximal reduction
• Relocating contact points by crown contouring or restor-
ative dentistry.
• Cosmetic restorations
• Correcting tooth angulation.
• Tooth extrusion to relocate alveolar crest more inciso-
occlusally.
5. Tooth Shade and Color
The shade of the teeth changes with age. Teeth appear lighter
and brighter at a younger age, darker and duller as aging pro-
gresses; this is related to the formation of secondary dentin
and thinning of the facial enamel, resulting in a decrease in its
translucency and a greater contribution of the darker under-
lying dentin to the shade of the tooth. The maxillary central
incisors tend to be the brightest while smiling, while the ca-
nines are the least bright. The first and second premolars are
lighter and brighter than the canines, more closely matched
the lateral incisors.

8
Other dental features
1. Overjet: It is the horizontal overlap of the incisors. The
average value given is 2-4 mm (Cobourne and DiBiase,
2015, Proffit et al., 2018). The difference might be due
to measuring technique in the British and ABO systems.
According to British standards overjet is measured from
the labial surface of the most prominent maxillary in-
cisor to the labial surface of the mandibular incisors.
According to ABO overjet is measured between two
antagonistic anterior teeth (lateral or central incisors)
comprising the greatest overjet and is measured from the
facial surface of the most lingual mandibular tooth to the
middle of the incisal edge of the more facially positioned
maxillary tooth. Proffit (Proffit et al., 2018) classified
overjet of Class II cases as follows:
• Mild = 3-4 mm
• Moderate = 5-6 mm
• Severe = 7-10 mm
• Extreme = > 10 mm
For Class III cases, overjet is classified into:
• Mild = 0 mm
• Moderate = -1to -2mm
• Severe = -3 to –4mm
• Extreme = > -4 mm
2. Overbite: It is the amount of vertical overlap of maxillary
incisors over mandibular incisors. The normal range is
2-4 mm or 1/3 to ½ of the lower incisal crown height. A
complete overbite represents the overbite relationship in
the presence of positive contact between the opposing
incisors or the incisors and opposing mucosa. Incom-
plete overbite represents a lack of contact between the
opposing incisor or mucosa despite the positive vertical.
While the traumatic bite is a subtype of complete over-
bite with evidence of trauma to either the palatal mu-
cosa or to the gingivae of the lower labial segment.Proffit
(Proffit et al., 2018) suggested 2 mm as a normal value
for an overbite, beyond this value, the term deep bite is
used. Hence, an overbite of 3-4 mm is classified as mod-
erate deep bite, 5-7mm as severe deep bite and greater
than 7mm as an extreme deep bite. On the other hand,
open bite is defined as a lack of vertical overlap between
upper and lower incisors. Open bite is classified into: a)
Moderate = 0 to -2mm, b) Severe = -2 to -4mm and c)
Extreme = >-4 mm.
3. Transverse buccal relationship: The maxillary dentition
should overlap the mandibular dentition, a deviation
from this relationship is considered as a crossbite. There
are two main types of crossbite: anterior and posterior
crossbite. Anterior crossbite is also called reverse overjet.
In terms of posterior crossbite, there is variation in the
description between different schools of thought. British
school considers the mandible as a reference jaw when
defining posterior crossbite in contrary to the Americans
who consider the maxilla as a reference. Therefore, in the
UK, a posterior lingual crossbite means that the palatal
cusps of the maxillary dentition are occluding buccally
to the buccal cusps of the mandibular dentition which is
opposite to the definition adopted in North America. To
avoid confusion, the glossary of orthodontic terms uses
the terms maxillary buccal crossbite for maxillary teeth
which are more buccal and maxillary lingual crossbite
for maxillary teeth which are more lingual.
4. Occlusal plane: Upper and lower occlusal planes should
be assessed using a fox bite or wooden tongue depressor
and should be parallel to the interpupillary line in the
absence of vertical orbital dystopia, otherwise, they are
described as a cant. In the presence of orbital dystopia,
the true horizontal should be used. In this case a direct
evaluation is difficult and it is better to take a photograph
with the patient biting on the wooden plate and then as-
sess it. Upper and lower occlusal planes are subdivided
into anterior and posterior (Bell, 1980).. The posterior
cant represents a skeletal problem while the anterior cant
represents a dental problem, or it might be secondary to
the posterior cant.
5. Maxillary dental midline: It should be assessed in rela-
tion to middle of the philtrum of upper lip (Cupid’s bow)
and to the facial midline. According to a systematic re-
view (Janson et al., 2011), a dental midline deviation of
2.2 mm can be considered acceptable by both orthodon-
tists and laypeople, whereas the axial midline angulation
of the incisors should not exceed 10° (2 mm measured
from the midline papilla and the incisal edges of the inci-
sors).
6. Mandibular dental midline: It is assessed in relation to
midpoint of chin and to the facial midline and in relation
to the maxillary dental midline.
7. Space Analysis: Please refer to the relevant chapters

Exam Night Review
Clinical facial, smile and dental analysis
Factors that affect the values during CFA
• Racial background
• Cultural difference
• Gender
• Personal preference
• Clinician philosophy
Common Landmarks used in Facial Anthropometry
• Inferior Labrale Superius (ILs): A landmark on the up-
per lip located midway between Labrale Superius and
Stomion Superius.
• Labrale inferius (Li) : A point indicating the muco-cu-
taneous border of the lower lip.
• Labrale superius (Ls) : A point indicating the muco-
cutaneous junction of the upper lip and philtrum.
• Nasion (N): The point in the midline of both the nasal
root and the nasofrontal suture, always above the line
that connects the two inner canthi, identical to bony na-
sion.
• Pogonion (Pog): The most anterior midpoint of the
chin, located on the skin surface in front of the identical
bony landmark of the mandible.
• Pronasale (Prn) : The most protruded point of the apex
nose identified in lateral view of the rest position of the
head.
• Soft tissue A point: The deepest midline point on the
upper lip, which is located usually halfway between Sn
and Ls.
• Soft tissue B point: The deepest midline point on the
labiomental fold, which determines the lower border of
the lower lip or the upper border of the chin.
• Subnasale (Sn) : The midpoint of the angle at the colu-
mella base where the lower border of the nasal septum
and surface of the upper lip meet.
• Superior Labrale Inferius (SLi) : A landmark on the
lower lip located midway between Stomion Inferius and
Labrale Inferius.
Frontal facial analysis
• Vertical analysis of the frontal view
• Transverse analysis of the frontal view
• Profile analysis
• Smile analysis
Factors affecting lip incompetency
• With aging, the lip incompetency is reduced
• Short lip
• Increased lower anterior face height (LAFH) due to ver-
tical maxillary excess VME
• Increased LAFH due posterior growth rotation,
• Over-eruption of the buccal segment,
• Anteroposterior (AP) skeletal malrelationships.
• Proclined upper labial segment (Paulsen et al.) or lower
labial segment (LLS)
Smile arc
• Contour of the maxillary anterior teeth incisal edges
relative to the curvature of the lower lip during social
smile. Perhaps a better way of stating it would be “The
arc formed by a line passing through the the incisal edges
of the maxillary anterior sextant”
• For best appearance, the contour of these teeth should
match that of the lower lip → consonant smile.
Factors affecting buccal corridor
a. Arch form
b. Anterior posterior position of the maxilla
c. Transverse maxillary deficiency
d. Expansion of the maxillary arch → reduce negative space.
Excessive expansion → may result in complete elimina-
tion of the buccal corridors
e. Palatally inclined maxillary posterior teeth → increased
buccal corridors.
f. Wide commissure
Dental midlines
• Maxillary dental midline is assessed in relation to middle
of philtrum of upper lip (Cupid’s bow) and to the facial
midline.
• Mandibular dental midline is assessed in relation to mid-
point of chin and to the facial midline and in relation to
maxillary dental midline.
• According to a systematic review (Janson et al., 2011) a
dental midline deviation of 2.2 mm can be considered
acceptable by both orthodontists and laypeople, whereas
incisors axial midline angulation should not exceed 10°
(2 mm measured from the midline papilla and the incisal
edges of the incisors)
Mixed Dentition Analysis
In mixed dentition space analysis, mesiodistal width of

10
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12

2
1. Goals of imaging
2. Classification of imaging techniques
3. Radiographic imaging techniques
4. Essential legal requirements of IRMER 2000
5. X-Ray variables
6. Measurements of radiation doses
7. Digital radiography
8. Image receptors – film and digital
9. Periapical radiographs
10. Bitewing radiographs
11. Orthopanoramic radiography (OPG)
12. Lateral cephalogram
13. Projection error
14. Template analyses
15. Pitchfork analysis
16. Pancherz analysis
17. Bolton template analysis
18. 3D cephalometric superimpositions
19. Computed tomography (C.T.)
20. Cone Beam Computerized Tomography (CBCT)
21. Frontal cephalometry/ posteroanterior view
22. Radionuclide imaging
23. Non-ionizing imaging techniques
24. 3D digital study models
25. Stereo photogrammetry
26. Laser scanning
27. Structured light imaging
In this Chapter
Imaging In
Orthodontics:
Radiography &
Photography
Written by: Mohammed Almuzian, Haris Khan,Taimoor Khan, Awrisha Tariq, Syed A. A. Bukhari, Amna
Sabeeh Noor

Imaging In Orthodontics: Radiography And Photography
14
Imaging is the process of making a visual representation of
something (the creation of an image).
Goals of imaging
These include:
• Obtaining an image of the region of interest (Graber et
al., 2016).
• Viewing the area of interest in at least two planes at
right angles to each other.
• Obtaining images with maximum detail, minimal dis-
tortion, and minimal superimposition,
Classification of imaging techniques
There are two main types of imaging techniques, two and
three-dimensional images. Conventional radiographs are
two-dimensional images of a three-dimensional objects,
while three-dimensional imaging reflects the true form of
the object under consideration in a 1:1 image to size ratio.
There are several types of imaging techniques such as ra-
diography, clinical photography, digital, video, and optical.
Imaging techniques can be also categorised into ionizing
and non-ionising imaging techniques.
Radiographic imaging techniques
Wilhelm Rontgen discovered X-rays in 1895. Since then,
there have been rapid advances in imaging technology. First
dental radiograph was taken within 2 weeks of discovery
of X-ray by Dr. Otto Walkoff (Germany) and Dr. Frank
Harrison (UK). In 1921, the first formal recommendation
of radiation protection in the U.K. were published by the
British X-ray and Radium Protection Committee. In 1928,
the International Commission on Radiological Protection
(ICRP) was established.
Radiation guidelines
In clinical orthodontics, all radiation doses must be kept as
low as reasonably practicable (ALARP), and X-rays should
only be prescribed with clinical justifications. In the UK,
taking x-rays is governed by some regulatory bodies includ-
ing:
• The Ionising Radiations Regulations 1999 (IRR 99)
which is concerned with the safety of the workers and
the general public.
• The Ionising Radiation Medical Exposure Regulations
2000 (IRMER) which is concerned with the protection
of patients.
• Health Protection Agency.
• European commission for CBCT (SEDENTEX 2011).
• The British Orthodontic Society guidelines (Isaacson
and Thom, 2015).
Key aspects of IRMER 2000
The main aspects are:
• Justification must be based on the aim of exposure,
potential benefits, risks,diagnostic needs, the efficacy,
benefits and risks of alternative techniques.
• Optimization: This refers to reducing the ionizing dose
as low as reasonably practicable (ALARP) by increasing
the KV, using digital film, fast speed film, collimator,
film holder, staff training and regular quality assurance.
• Pregnant staff should not receive more than 1 mSv of
radiation to the abdomen, and should consult radiation
protection advisor if taking more than 150 radiographs
per week.
• 2 meter distance should be maintained from the pri-
mary X-ray beam to operating staff.
• Lead aprons are no longer justified for routine use
in dental photography and its use during panoramic
radiography is positively discouraged. (Guidelines on
Radiology Standards in Primary Dental Care. NRPB/
RCR Working Party 1994)
• Finally, there is no requirement of routine thyroid collar
use.
X-Ray variables
These include:
• Kilo voltage (kV): It is the potential difference across
an x-ray tube, which determines the speed with which
electrons travel in the tube. Intraoral x-ray machines
produce kV between 65-70, while extraoral machines
produce kV that ranges from 70-120. kV determines
the quality of the x-ray beam, which is the energy of
photons and penetrating power of photons. The higher
the kV, the more likely the photon could pass through
the patient. kV also reduces the dose of x-rays as more
photons pass through the patient, which reduces expo-
sure time. kV affects the contrast of film in an inverse
relationship. If kVs increase, the contrast is reduced
between different tissues as more x-rays pass through
calcified tissue as well as non-calcified tissues. Increas-
ing or decreasing the kV changes the amount of radia-
tion exposure.
• Miliamp (mA) and time (s): Milliamp is the current
flowing through the tube that is the number of elec-
trons circulating. Mostly, 7-12 mA is used for intraoral
radiography. Milliamp determines the quantity of x-ray
photons and it also affects the blackening of the film
as the overexposed film is too black. As the mAs is de-
creased, the amount of radiation decreased. Milliampes
and exposure time have an inverse relationship.
Measurements of radiation doses

Imaging In Orthodontics: Radiography And Photography 15
• Absorbed Dose (D): It is a measurement of the amount
of energy absorbed from the x-ray beam per unit mass
of tissue. D dose is used to assess the potential for
changes in the tissues. It is measured in Joules/kg, the
standard international (S.I.) unit is the Gray (Gy).
• Equivalent dose (H): It is a measurement of radiation
dose that takes into account damage caused by different
types of radiation. Each type of radiation is allocated a
different radiation weighting factor (W.R.). X-rays and
gamma rays have a weighting factor of 1, while the more
damaging protons and alpha particles have a weighting
factor of 2 and 20, respectively. H dose is calculated by
multiplying the radiation absorbed dose (the amount of
energy absorbed by the tissue) by the radiation weight-
ing factor (W.R.) for the type of radiation being used. It
is used to assess the amount of potential damage from
the radiation to the tissues. The standard international
unit is the Sievert (Sv). H = D x radiation weighting
factor (Sievert).
• Effective dose (E): It is a measurement of radiation
dose that takes into account the sensitivity of X-rays by
different tissues of the body. Each radiosensitive tissue
/ organ in the body is given a specific tissue weighting
factors. When an exposure involves one of these tissues,
the equivalent dose is multiplied by the appropriate tis-
sue weighting factor (Wt) to provide an effective dose.
This dose can be used to compare absorption capacity
of different parts of the body. It is used to assess the
potential long term effects of the radiation dose. The ef-
fective annual natural exposure to background radiation
is approximately 2400 μSv at sea level (ranges from 1000
to 3000 μSv). Consequently, the natural background
radiation is estimated to be about 0.08 mSv per day.
The radiation dose of CBCTs is 2 to 6 times higher than
plane radiographs. For CBCT lateral cephalograms Vs
plane lateral cephalograms, the radiation dose is 15 to
26 times higher (Signorelli et al., 2016). E= H x tissue
weighting factor (Sieverts).
Digital radiography
Digital images need to be securely saved and backed up to
an appropriate computer / cloud / server. In most hospitals,
this storage is accomplished using a Picture Archiving &
Communication System (PACS). Benefits of digital radiog-
raphy over conventional one are (Forsyth et al., 1996a):
• Electronic storage and transmission.
• Reduced processing time and reduced clinic time.
• Reduced radiation exposure of up to 30-50%.
• The identical image can be viewed on different displays.
• Image can be transferred for seeking opinions.
• Fast transfer to remote locations via an appropriate
network.
• More environmentally friendly with reusable plates and
no processing chemicals (Brennan, 2002).
• Some software programs have ‘audit trail’ features,
which can track and recover original RAW images.
• Image enhancement is possible to improve the diagnos-
tic quality of digital images (Forsyth et al., 1996b).
X-ray
Technique
Effective
dose
(µSv)
Risk of
cancer
Per million
Equivalent
background
radiation
(days)
Intraoral
radiograph
(bitewing
and periapi-
cal)
≤10 ≤0.5 1/4th of a
day
Anterior
maxillary
occlusal
8 ≤0.5 1.2 days
Panoramic ≤30 ≤2 0.5-5 days
Lateral
cephalomet-
ric radio-
graphs
≤3 ≤1 1/3rd of a
day
Cross-
sectional
tomography
(single slice)
Very wide
range but
≤189
Very wide
range but
≤14
-
Cone beam
CT (doses
for full field
of view)
Very wide
range but
typically
between ≤50
and ≤ 500
Very wide
range but
≤50
26 days
CT scan
mandible
Very wide
range but
≤3300
Very wide
range but
≤250
15-455 days
Chest 20 2 3 days
Barium
swallow
1.5mSv - -
Barium
enema
2.2mSv - 390 days
CBCT small
vol
10-67 - 4-10 days
CBCT large
vol
30-1100 - 10-42 days

16
ment operating at less than 70kV should include 1.5 mm
of aluminum filtration, and 2.5mm if working over 70kV.
Equipment should ideally include rectangular collimation
(40 x 50mm), but if circular beams are used, they should
not exceed 60 mm in diameter. Equipment should also have
film speed controls, adjustable kV, mA, and exposure times.
Equipment should ideally have D.C. or constant potential
output. Focal spot position should be marked on the tube
head casing. The focus-to-skin distance (FSD) should be a
minimum of 200 mm.
Occlusal radiographs
Occlusal radiographs are particularly useful in the maxillary
arch for assessing root form/ shape of the incisors, presence
of midline supernumerary teeth and location of impacted
canine position, either alone or in combination with ad-
ditional views using the parallax technique. For occlusal ra-
diographs, the film is placed between occlusal surfaces. The
normal angulation of the x-ray tube is 60-65 degrees to the
true horizontal plane, which is increased to 70-75 degrees
for vertical parallax (Jacobs, 1999).
Periapical radiographs
Periapical radiographs are useful for the detection and as-
sessment of local pathology, root form, root resorption, api-
cal disease, presence and position of unerupted teeth. They
can also be used with the parallax technique, for example
in identifying the buccolingual position of impacted upper
canines and supernumerary teeth. Two methods of parallax
can be used:
• Vertical parallax: A single periapical radiograph along
with another radiographic view, such as an upper stan-
dard occlusal or DPT
• Horizontal parallax: Two periapical radiographs are
taken with horizontal tube shift (at least 20 degrees) be-
tween them. Horizontal parallax has a higher sensitivity
in detecting impacted canines of 83%, when compared
to vertical parallax of 68% (Armstrong et al., 2003).
Bitewing radiographs
Bitewings are accurate in the detection of interproximal car-
ies, assessment of existing restorations and for periodontal
status. Bitewings may be indicated to check the caries status
of a high-risk patient, who need fixed appliance treatment.
Orthopanoramic radiography (OPG)
OPG employs the principle of tomography or sectional
radiology (Quintero et al., 1999). Accurate positioning of
patient is ensured by light beam markers. The main purpose
of OPG are:
• To confirm the presence, position, and morphology of
unerupted teeth.
• To provides an overview of developing dentition spe-
Tissue weighting factor of important organs (Wt)
Salivary glands 0.01
Skin 0.01
Thyroid 0.04
Gonads 0.08
Breast 0.12
Red Bone marrow 0.12
Disadvantages of digital radiographical imaging
These include:
• An initial outlay of costs to convert from conventional
imaging systems (Brennan, 2002).
• CCD systems can be bulky and have fibre optic wires,
which can be damaged during use.
• Cross infection control has to be managed.
• Medicolegal concerns could arise from manipulatied
images.
Image receptors
These include:
• Conventional radiographic film: It could be direct ac-
tion or packet film (intra-oral) or indirect action film
that is used in conjunction with rare-earth intensifying
screens in a cassette (extra-oral). In terms of receptors,
there are two types of receptors for direct digital image
acquisition: charge-coupled devices (CCD) and storage
phosphor (S.P.) image plate (Isaacson and Thom, 2015).
• Phosphor plate: An example of phosphor plate is the
photostimulable phosphor plates which typically consist
of a layer of barium fluorohalide phosphor on a flexible
plastic support. Suitable size phosphor plates are avail-
able for all dental radiographic techniques. Following
exposure, the plates are read by a laser scanning device
to present images on a monitor.
• Solid-state sensors: It consist of a scintillator that con-
verts x-radiation to light. The scintillator is mounted
on a photodetector and the associated electronics are
encased in a small, thin, flat, rigid, plastic rectangular
housing. The underlying technology of solid-state sen-
sors involves either amorphous silicon-based charge-
coupled devices (CCD) or complementary metal-oxide
semiconductors (CMOS). Suitably size sensors are
available for periapical/bitewing, panoramic, and skull
radiography. After exposure, the image processes and
appears instantly on a monitor.
Setting the chair-side dental X-ray equipment
The operating range should be in the range of 60-70kV
and operate within 10% of the stated or selected kV. Equip-

cially 3rd molar (Isaacson and Thom, 2015).
• To assess the angulation of roots can be assessed.
• Screening of frank pathology before commencement of
orthodontic treatment.
OPG machine should have a range of tube potential set-
tings, preferably from 60 to 90 kV. Beam height should not
be higher than the image receptor in use (usually 125mm or
150mm). Equipment needs to be provided with patient posi-
tioning aids, incorporating light beam markers. New equip-
ment should offer facilities to field-limitation techniques and
appropriate collimation of OPG images, such as ‘dentition
only’ which results in a 50% dose reduction.
Shortcomings of OPG
These include:
• Lack of sharpness due to various factors including
ghost imaging, superimposition, static distortion, and
processing errors.
• Horizontal distortion tends to be a non-linear distor-
tion.
• The vertical distortion is considered to be twice as sig-
nificant at image distortion as horizontal distortion.
• Superimposition of the cervical spine.
• Limited focal trough in the incisor region. If the lower
incisor region is out of the focal trough, the apices and
associated structures may be out of focus or even invis-
ible. Lingually-positioned roots falling outside the focal
trough are usually magnified. Similarly, excessively in-
clined teeth not contained within the boundaries of the
focal trough may appear narrow or foreshortened on
the resultant image. Consequently, the anterior region
of the OPG may be non-diagnostic and unrepresenta-
tive of the anatomy.
• Only gross caries will be detected with acceptable accu-
racy with an OPG. Therefore, caries diagnosis requires
clinical examination supplemented by bitewing radiog-
raphy.
Lateral cephalogram
Cephalogram means ‘measurement of the head’. More com-
monly, it refers to the use of standardized skull radiograph
to assess facial, dental, skeletal relationships and airway
analysis. The technique was developed in the 1930’s by
Broadbent (USA) and Hofrath (Germany). Cephalogram is
the most widely used imaging modality in orthodontic in-
vestigation. Lateral cephalometric skull radiographs should
fulfill the following criteria:
• There should be accurate patient positioning, assisted by
light beam markers.
• It should include triangular collimation, facilitated by a
light beam diaphragm, to reduce X-ray exposure to the
cranium and neck.
• The collimated X-ray source is 5 feet from the midsagit-
tal plane of the patient.
• It should include an aluminium wedge filter, ideally at
the X-ray tube head, to facilitate the imaging of the soft
tissues.
• The film should be placed 1 foot behind the midsagittal
plane of the patient, to minimize magnification, with a
rare earth metal intensifying screen.
Indications and applications of lateral cephalogram
These include:
• Diagnosis and treatment planning.
• Baseline for monitoring treatment progress.
• Cephalometric radiographs can help in the location and
assessment of unerupted, malformed, and misplaced
teeth.
• Assess upper incisor root length.
• Assess skeletal pattern.
• Serial lateral cephalograms have some application in
monitoring the growth in skeletal class 3 patients, or
to assess and monitor growth by serial radiographs.
However, there is a lack of high-quality evidence to sup-
port the use of lateral cephalograms for the prediction
of facial growth.
• Assessment of soft tissue profile.
• Airway assessment, though it is not reliable for this
purpose.
• Research purposes.
The routine use of lateral cephalometric analysis in
orthodontiocs is controversial. Some believe that lateral
cephalograms are unlikely to be required if the incisor rela-
tionship does not require significant change. Others stated
that using a cephalogram doesn’t change orthodontic treat-
ment planning (Devereux et al., 2011); instead, the study
model is considered enough diagnostic information for
treatment planning in 55% of Class II cases (Han et al., 1991,
Rischen et al., 2013). However, in general, lateral cephalom-
teric radiograph are prescribed in cases that require:
• Fixed appliances in upper and lower arches, and the inci-
sor position needed to be changed.
• Functional appliance therapy.
• Class II and III malocclusion and bimaxillary protrusion.
• When the malocclusion is significant i.e. in a child of less

18
than ten years with Class 2 or 3 jaw relationship, which
may require early treatment or monitoring.
• When the labiolingual movement of incisors is antici-
pated, and significant changes are to be made.
• If the patient requires orthognathic surgery.
Types of errors in cephalometric analysis
These include systematic error (due to different concepts of
landmark identification) and random error which includes
projection errors, errors of identification and errors within
the measuring system.
Projection error
Projection error occurs due to 2-dimensional radiographs
representing 3-dimensional objects. Landmarks outside of
the mid-sagittal plane (para-mid-sagittal) are distorted by
projection error, resulting in obtuse angular measurements
and shortened linear measurements. Landmarks in the
midsagittal plane are unaffected. Types of projection errors
are magnification and head position errors. Magnification
error can be quantified using calibrated metal strip / scales.
Magnification errorr for linear measurements, range from
7-10% while angular measurements are unaffected. Image
magnification is constant for each individual machine. If
lateral cephalograms are produced using different machine,
there is likely a variation in magnification projection error,
therefore, calibration and standardisation are essential. A
short focal distance increases projection errors while long
focal distance decreases projection errors.
To reduce head position error, lateral cephalograms should
be taken in centric relation with Frankfort plane horizontal
or natural head position (NHP) as reference. It is also es-
sential to control magnification by the correct focal object
distance and have correct head position.
Landmark identification error
All landmarks have an ‘envelope of error’ which is depen-
dent on anatomic characteristics of landmark, for instance
points on edges of the anatomical structures are easier to
locate than points within structures. To reduce identification
errors a clear understanding of the definition is required,
automated or semi-automated radiographic identification of
landmarks (artificial intelligence) can be used and alumini-
um wedge for better sharpness is recommended.
Registration error
Although registration can be manual or digital, there is no
difference between manual and digital tracing (Santoro et
al., 2006, Naoumova and Lindman, 2009).
Measurement error
It is due to difference in the applied cephalometric analysis
(different methods of cephalometric analysis are available,
some are more complicated than others, the method chosen
should reflect clinical / research use) or operator error which
is influenced by experience and calibration.
Environment factors
These include lightbox, ambient light conditions, and quality
of the image.
Methods to reduce measurement error
These include:
• Careful selection of analysis method.
• Error calculation.
• Care when interpreting results.
• Good quality film and standardisation.
Advantages of on-screen digitizing
These include (Sandler et al., 2002):
• Cost saving with no requirement of lightboxes / trac-
ing units.
• Adjustable brightness and contrast to make identifica-
tion of hard and soft tissues easier.
• Useful teaching tool.
Assessing treatment changes using lateral cephalograms
Analysis of changes secondary to orthodontic treatment take
place through the superimposition of 2 or more cephalo-
gram. The facial skeleton can be assessed as a single entity
(total facial skeleton), or each jaw can be assessed indepen-
dently. For total facial skeleton analysis, many techniques
have been proposed, such as:
• Superimposition on S-N plane registered at S: Pre- and
post-treatment cephalograms are superimposed on the
SN reference line. S-N is an easy reference line but the
position of nasion may change due to growth at fronto-
nasal suture making S-N an unreliable reference line for
superimposition.
• Superimposition on DeCoster line: Lucien DeCoster in
1952 described the basicranial line or anterior cranial
base as a stable structure, which represented the axis of
the skull base and was therefore suitable for the com-
parison of changes in the facial bones (De Coster, 2007).
The DeCoster line extends along with the anterior lip of
Sella turcica, sphenoethmoid suture, planum sphenoi-
dal, the roof of the ethmoid and the cranial side of the
frontal bone.
• Superimposition on Björk’s stable structures: Björk and
Skieller further defining the precise anatomical land-
marks along the anterior cranial base that should be
utilized on the basis of stability (Björk and Skieller,
1983), these include the anterior wall of sella turcica

and its intersection with the anterior clinoid process,
cribriform plate of the ethmoid, frontoethmoidal crest.
and the cerebral surface of the orbital roofs.
• Superimposition using Ricketts’ method: It uses the entire
length of the cranial base along a line constructed from
nasion to basion.
Maxillary skeletal and dental changes
Maxillary superimposition allows the assessment of dental
changes. For maxillary skeletal and dental changes, the two
common techniques are Björk’s and Ricketts’s method. For
Björk’s method for superimposition, the anterior contour of
the zygomatic process is used as the reference line.
Using Ricketts’ method, nasion-pterygomaxillary is used
as reference plane, registered at the pterygomaxillary point.
This point is supposed to represent the foramen rotundum,
the point of exit of the maxillary branch of the trigeminal
nerve from the intracranial cavity.
Mandibular skeletal and dental changes
Simialr to maxillary superimposition, mandibular superim-
position allows the assessment of dental changes and can be
undertaken using Björk’s or Ricketts’s method. With Björk’s
method, the several structures are considered stable points
/ areas for registration of superimposition, these include
anterior contour of the chin, inner contour of the symphysis,
any distinct trabecular structures in the symphysis, contour
of the mandibular canal and lower contour of a mineralized
tooth germ (premolar or molar) present in both cephalo-
grams. With Ricketts’ method, registration is taken place
at the CC point, which is the point of intersection of a line
constructed from the pterygomaxilla (Pt) to gnathion.
Template analyses
Template analyses are a method of cephalometric analysis
and superimposition based on the construction of a specific
reference plane, which is used for both analysis and super-
imposition.
Pitchfork analysis
It is a popular superimposition technique in which the refer-
ence structures is the maxilla, zygomatic plates and zygoma.
A paper by Mannchen (Männchen, 2001), has described
some disadvantages of the pitchfork analysis including that
the maxilla is not a stable structure on which to superim-
pose, rotational changes of the maxilla during treatment
could affect the antero-posterior assessment. Moreover, the
mean functional occlusal plane can change and affect mea-
surements relative to it.
Pancherz analysis
Pancherz analysis is similar in principal to the pitchfork
analysis. This method analyse the anterior-posterior changes
in the maxilla, mandible and dentition. It relies upon a com-
mon perpendicular line to the maxillary occlusal functional
plane from the first tracing, which is used in the subsequent
tracing after superimposition on the cranial base line (SN
line).
Bolton template analysis
Bolton analysis has two forms, the schematic template which
assess the changes in position of selected landmarks with
age on a single template and the the anatomically complete
template which uses a different template for each age. It is
particularly convenient for direct visual comparison of a
patient to a reference group while accounting for age related
changes.
3D cephalometric superimpositions
3D CBCT images can be superimposed by manual registra-
tion of landmarks or by the best fit of landmark regions.
The different methods to superimpose 3D images are
voxel-based, landmark-based, and surface-based registra-
tion (Cevidanes et al., 2006). Surface-based and voxel-based
superimposition methods using the anterior cranial base as
a reference structure, and are accurate and reliable in detect-
ing changes. Landmark-based superimposition method
is less accurate than the other methods (Ghoneima et al.,
2017).
Computed tomography (C.T.)
Tomography is a general term for a technique that provides
an image of a layer of tissue. 3D images such as magnetic
resonance imaging and computed tomography (C.T.). The
data is recorded on solid-state image detectors arranged in
a 360˚ array around the patient. A series of axial plane slices
are captured as individual stacked slices or from a continu-
ous spiral motion over the axial plane.
C.T. scan has a higher sensitivity in assessing the presence
of root resorption (48%) when compared with conventional
radiographs (12%) (Ericson and Kurol, 2000). The sensitiv-
ity of C.T. scan for bone mass lesions is excellent though soft
tissue sensitivity is poor when compared to a MRI.
It is advisable to select the smallest field of view required for
clinical evaluation to reduce exposure. C.T. scans for implant
placement is asscoiated with an effective dose of 30 to 650
mSv.
Cone Beam Computerized Tomography (CBCT)
Although low-dose protocols for CBCT imaging seem to
have potential in various disciplines in dental medicine
ranging from pediatric dentistry to oral and maxillofacial
surgery, CBCT should be used cautiously and in carefully
in selected scenarios. Dose reduction is usually achieved by
mAs reduction, use of partial rotations, reduced number of
projections, and larger voxel sizes, but seldom by kV reduc-
tion (Yeung, 2019). It is used as an adjunct to 2D imaging to
improve patient outcomes (Drage, 2018).

20
CBCT unit
The main features of the CBCT unit are:
• In this technique, a cone-shaped X-ray beam rotates
around the patient to acquire volumetric data of the
region of interest with a single rotation (Merrett et al.,
2009).
• The equipment for CBCT resembles panoramic units. It
involves a cone-shaped x-ray beam, flat-panel detectors
and image intensifiers (amorphous silicon or comple-
mentary metal-oxide semiconductors).
• The X-ray tube has a variable potential between 60-
120kV.
• Scan time varies from 5-90 seconds while the patient is
exposed to radiation for 3.5 seconds.
• The overall effective dose has been estimated at 50 – 500
μSv depending on exposure time/ mAs.
Rationale and uses of CBCT in orthodontics
A clinical justification should be based on the risk-benefit
ratio of radiation exposure (Oenning, 2018). Generally,
CBCT should not be prescribed unless its diagnostic infor-
mation improves treatment outcomes and if plain 2D views
do not show enough information for a particular clinical
question (SEDENTEX 2011).
Generally, CBCT imaging is useful in cases with:
• Impacted teeth: CBCT aids in surgical planning (Botti-
celli et al., 2011), and aid in determining the mechanics
and force direction.
• Supernumerary teeth.
• Root resorption (Yi et al., 2017).
• Cleft lip and palate (Kuijpers et al., 2014b, De Grauwe et
al., 2019).
• Orthognathic surgery planning: 3D surgical predic-
tions, superimpositions of treatment outcome, and
growth change evaluation in three dimensions can be
performed. Surgical outcomes can be evaluated, and
this can be of great value for the orthodontist and the
patient.
• Assessment of RME.
• Planning for miniscrew placement.
• Airway analysis (questionable).
• Transplantation: CBCT can be used to prepare a
template / 3D replica in the recipient site, as well as for
assessment of root resorption and position of teeth in
the alveolar housing.
• Developmental abnormalities: Such as dilacerations,
the number of roots or dens evagination.
• Root fracture.
• Dental implant: Assessment of bone height, width,
quality, relation with adjacent structures. implant born
frameworks and abutments can also now be produced
using CAD/CAM technology).
• Endo-perio lesion.
• Complicated root canal treatment.
Advantages of CBCT
These include:
• Less distortion than conventional 2D radiographs.
• Limited magnification error.
• Ability to correct head position after the image is cap-
tured.
• Less structural superimposition compared to conven-
tional radiographs.
• Better imaging of the bone and dental hard tissue com-
pared to C.T. scan.
• CBCT image helps in surgical planning by allowing the
visualization of exact movements of jaws.
• CBCT equipment is smaller than a C.T. equipment.
• Reasonable degree of sensitivity in detecting root re-
sorption is 66.7% (Walker et al., 2005).
Disadvantages of CBCT
These include (Drage, 2018):
• High cost.
• Extensive training is required to fully evaluate the image
as it is a legal requirement to report on the entire image
taken.
• The patient is required to stay still for 10-40 seconds.
• Increased artefacts, image scatter and noise which de-
creases the ability to differentiate low contrast visibility
tissues (Garayoa and Castro, 2013).
• Beam hardening and streak artifacts around dental res-
torations can render diagnosis (Elstrøm et al., 2011).
• Low dose CBCT X-rays can result in low quality images.
• There is no robust evidence showing improvement in
treatment outcomes with the uses of CBCT scans. A
study in Cardiff showed that the incidental finding of a
CBCT which could changed the treatment plan is less
than 1% (Drage et al., 2013).
• Dental CBCT is not indicated for soft tissue analysis,
such as malignant tumours, phlegmon, and other forms

of extensive inflammation.
Frontal cephalometry/ posteroanterior radiographs
Frontal cephalometry can be helpful in the assessment of
specific jaw or dental anomalies or functional asymmetries
and asymmetries.
Hand or wrist radiographs
In the UK, it is no longer necessary to take hand or wrist
radiographs to assess skeletal maturation.
Radionuclide imaging
This procedure involves localization of regions of cellular
activity within a patient in which the patient is adminis-
tered with one or more nuclides. The common radionu-
clide imaging that is used in orthodontics is Technetium 99
which is helpful in assessing current growth in patients with
facial asymmetry, and identifying ‘hot spots’ of asymmetric
growth.
Damaging effects of ionizing radiation
Dental radiography accounts for about 25% of all radiog-
raphy in the U.K. Historically, dental radiography required
high doses of radiations that produced local side effects like
skin reddening, hair loss, ulceration and cancer fatalities.
Unnecessary radiation from diagnostic radiographs cause
100-250 UK cancer fatalities. Generally, there are three
major categories of ionizing radiation side effects on human
tissue including:
• Somatic deterministic (certainty) effects which occur
when the threshold dose reached (10 Sv of total body ir-
ritation). These effects could be direct effects (abnormal
mitosis; degeneration and death of cells), indirect effects
(change in tissue due to damage to blood supply or
constitutional effects (such as malaise, nausea, vomiting,
decrease blood pressure, peripheral vascular failure, also
called radiation shock).
• Somatic stochastic (chance or random) effects: are not
dose dependent, and are due to chance. This means that
the severity of damage is not dependent on the amount
of exposure, but only the likelihood of harm being
increased. Somatic stochastic include neoplastic change
such as skin, bone sarcomas or leukaemia.
• Genetic stochastic (random) effects are shown in
offspring of recipient. For orthodontic radiography, it is
important to reduce radiation to skin, bone, bone mar-
row, thyroid, and salivary glands, especially in children
(Thorne, 1992). Children have higher risk from ionizing
radiation for two reasons: firstly, due to the higher cell
and tissue sensitivity to radiation than adults, secondly
due to the longer lifespan than adults in which radia-
tion-induced changes may manifest. Therefore, exami-
nation of children need to be performed carefully and
it should be kept to the minimum level necessary (the
exposure dose for children should be about half that
used in adults).
Non-ionizing imaging techniques
Digital 2D Photography
Photography in dentistry began in 1840 (Galante, 2009)
while digital photography boomed in mid-1990 (Kalpana
et al., 2018). The purposes of dental photography (Ahmad,
2009, Kalpana et al., 2018) are:
• Documentation.
• Communication (patients, dentist, etc).
• Diagnosis and treatment planning: It allows the ortho-
dontists to study the patient’s soft tissue pattern during
treatment planning phase. Lip morphology, tonicity,
smile arc, and smile aesthetics from various angles can
also be assessed.
• Self-education and reflection.
• Case presentation.
• Quality control.
• Research/teaching .
• Insurance verification.
• Marketing
• Medico-legal purposes.
Advantages of digital photography (Sandler and Murray,
2001)
These include:
• No fading in the image quality with time.
• Immediate viewing.
• No film or processing costs.
• Inexpensive storage.
• Easy retrieval.
• Easy duplication.
Requirement of digital photography
DSLR (digital single-lens reflex) cameras are highly recom-
mended for taking orthodontic photographic records. DSLR
camera consists of (Hutchinson and Williams, 1999, Lozano,
2015, Kalpana et al., 2018):
• Camera body (minimum of 4-5 Mega Pixels is re-
quired),
• Macro lenses (Fixed focal length of 85-105 mm, 1:2.8
Ultra Sonic Motor and Adjustable manual focus)
• Memory card,

22
• Flash (A ring flash of 1/2 power or twin flash). However,
a lightbox behind the patient for extraoral photos is
recommended.
In addition, there are special retractors and mirrors which
are used with intraoral photography including:
• U-shape cheek retractors for frontal intraoral photos.
• Fishtail-shaped cheek retractors for right and left intra-
oral photos, sometime used along with buccal mirrors.
• T-shape lip retractors for occlusal photos along with
occlusal mirrors.
Camera settings and position
It is recommended to take extra-oral photographs in
portrait mode and intra-oral photographs in landscape
mode. To achieve good digital dental photographs, stan-
dardisation of camera settings and patients posture is re-
quired (Hutchinson and Williams, 1999, Lozano, 2015,
Kalpana et al., 2018). Camera settings are also termed the
exposure triangle, depending on the type of the camera,
but commonly include:
• Aperture which is defined as the opening in a lens
through which light passes to enter the camera. Aper-
ture is represented by the F number or depth of field
(DoF). DoF refers to the aperture opening size of the
lens. Smaller f-number = more light and small aperture.
For extraoral photographs f/8, smile photographs f/32
and intraoral photographs f/22
• Shutter speed is the length of time camera shutter is
open, and the exposer of light to the camera sensor.
Simply it is how long the camera spends taking a photo.
In dental photography, this should be 1/60 seconds.
• ISO which brightens or darkens the photo. As the ISO
increase, photo becomes progressively brighter, in den-
tal photography, this should be 100-200.
Gold standard photos for orthodontic purpose
Nine pre-treatment and nine post-treatment images are
considered a minimum for orthodontic patients. This
entails four extraoral and five intraoral photos (Sandler
et al., 2002). A full set of progress photos are also rec-
ommended at important stages, ideally at each arch wire
change plus photographic details of the appliance. For
printing and publication purposes, the minimum resolu-
tion of 150-300 PPI is required in either JPEG or TIFF
format.
Intraoral scanning (oral scanner)
With intraoral scanning, a video camera records the struc-
tured light distortions on the dental surfaces as it passes
over the dentition. A computer processes these images and
merges them to create a complete 3D dental arch (Hajeer et
al., 2004). For diagnostic purposes, the accuracy of intraoral
scanner systems is comparable to the accuracy of conven-
tional impressions (Abduo and Elseyoufi, 201, Luqmani et
al., 2020).
Types of intraoral imaging techniques
These include:
• Scanner with parallel confocal imaging: With this tech-
nique, the scanner projects laser light through a pinhole
to the target. The sensor is placed at the imaging plane
where it is in focus (confocal). A small opening in front
of the sensor blocks any light from above or below.
Only the focused light reflecting off the target tissue
will reach the sensor for processing. This type of system
creates thousands of tomographic slices and combines
them together to form the three-dimensional picture.
For example iTero, Trios, Carestream.
• Scanner with triangulation imaging: With this tech-
nique, the scanner measures the angles and distances
from known points (laser source and sensor), with
projected laser light. It requires a thin coating of opaque
powder to be applied to the target tissue. The system
determines the angle of reflection and the distance from
the laser source to the object’s surface as light reflects off
the object. For example CEREC system (Chairside Eco-
nomical Restoration of Aesthetic Ceramics or Ceramic
Construction).
• Scanner with accordion fringe interferometry (AFI):
With this technique, two sources of light are used with
AFI to project three patterns of light, called fringe
patterns onto the teeth and tissue (True Definition
Scanner). Based on the shape of the object, the fringe
pattern distorts and takes on a new pattern. Surface data
points of the fringe curvature are recorded by a high-
definition video camera that is offset from the projector
by approximately 30˚. Because of the differences among
the three precision optical measurements, the distance
of different measures is determined. The differential
measurement is unaffected by changes in tooth colours
and materials.
• Scanner with three-dimensional in-motion video: With
this technique, the scanner utilises three tiny high-
definition video cameras to capture three precise views
of the target. A sensor behind the cameras converts
the light energy into electrical signals, which allows
the distances between two data points to be calculated
simultaneously from two perspectives in order to create
three-dimensional data. The data points are captured in
a video sequence and modelled in real-time. Although
powdering may be required to capture surface data
points, only a light dusting is needed, compared with
the thicker coating needed for triangulation. This scan-

ner was made by the Lythos Digital Impression Systems.
• Scanner with ClearView SCAN: With this technique,
the scanner uses high-definition ultrasound imaging to
capture both the tooth, bone and soft tissue in three di-
mensions. Early prototypes suggest that these scans will
use a disposable mouthpiece to scan the entire arch at
once and will be significantly faster and more accurate
than light-based scans. This scanner is made by S-Ray
Incorporated.
3D digital study models
Digital models offer a valid alternative to plaster study casts
(McNamara et al., 2011). A study found that 18% of practi-
tioners in the U.S use digital models (Keim et al., 2008).
Digital models can be substituted for plaster models with no
significant differences in the final treatment plan, the reli-
ability of the treatment plan, and the time required to create
the treatment plan (Sharma et al., 2019). The advantages of
digital study models over conventional models are (Martin
et al., 2015):
• Reduced requirement for model storage.
• No physical damage comapred to conventional models.
• Quick access to three-dimensional diagnostic informa-
tion.
• A virtual setup can be created for treatment planning
and manufacturing of fixed and removable appliances.
• Smooth transmission of digital data for communication
with professionals and patients.
• Reliable digital model measurements (Camardella et
al., 2020) with inter-arch and intra-arch measurements
from digital models from intraoral scans are more
reliable and accurate than conventional study models
(Aragón et al., 2016). A systematic review suggested
that digital models are as reliable as traditional plaster
models, with high accuracy, reliability, and reproduc-
ibility. Landmark identification, rather than the measur-
ing device or the software, appears to be the greatest
source of error. Furthermore, with their advantages in
terms of cost, time, and space required, digital models
could be considered the new gold standard in current
practice (Fleming et al., 2011) (Martin et al., 2015, De
Luca Canto et al., 2015)
Stereophotogrammetry
Stereophotogrammetry uses two cameras, arranged as a
stereo pair, to photograph an object from two different co-
planar planes. High-resolution images are captured at differ-
ent angles, and a three-dimensional image is reconstructed.
A software system is used to view and analyze the images
(Hajeer et al., 2004).This technique allows the recognition
of different facial landmarks, the measurement of linear and
angular values, and the detection of changes in face mor-
phology (Graber et al., 2016). This method is not suitable for
imaging study models.
Advantages of Stereophotogrammetry
These include:
• Stereophotogrammetry has low cost, safe, easy to oper-
ate with no radiation exposure.
• The advantages of stereophotogrammetry over CBCT
or laser scanning are short imaging times (less than 1
second) that minimize motion errors and high colour
resolution.
• Stereophotogrammetry can be combined with CBCT
images.
• Stereophotogrammetry allows orthodontists to evalu-
ate surface contours of a human subject rapidly and
objectively.
• Stereophotogrammetry is an accurate and reliable
imaging method for use in orthodontics, due to its
high intra-observer and inter-observer reproducibility
(Dindaroglu et al., 2016).
• Stereophotogrammetry can be used for facial superim-
positions after orthognathic surgery. Stereophotogram-
metry measurements relating the jaws to each other and
incisor orientation has a strong positive correlation with
corresponding traditional cephalometric measurements
and can serve as cephalometric predictors.
Laser scanning
Laser scanning is used for 3D facial scanning and construc-
tion of digital models (Ireland et al., 2008). The first 3D
scanning technology was created in the 1960’s in which the
scanners used lights, cameras and projectors to perform this
task.
Digital cameras monitor the illumination, and triangula
tion geometry allows depth information to be calculated.
The light source can be a point or plane, and the face can be
moved through the light source or vice versa. This technol-
ogy generally produces facial surfaces with accuracy and
resolution of 0.1 mm which is sufficient for detailing the
head and face and can take up to 30-60 seconds. In laser
scanning, the face is traversed by a laser light source (Hala-
zonetis, 2001).
Laser scanning provides surface map detail, and cannot
provide colour information, however a colour camera that is
registered with the laser scanner can capture colour detail.
Digital cameras monitor the illumination, and triangula
Advantages and disadvantages of laser scanning
These include:

24
• Portability and ease of use.
• Laser scans generate smooth images with all facial fea-
tures recorded in detail.
• Laser scanner is a reliable soft tissue imaging sys-
tem with a maximum measurement error of <1mm
(Kuijpers et al., 2014a). Although the accuracy of this
technique continues to improve with time, craniofacial
measurements obtained with laser scanners show excel-
lent reliability and accuracy, which qualifies this method
for clinical and scientific use.
• Laser scanning of study casts has many advantages over
other scanning techniques, despite the long-time of
acquisition. Areas of the undercut can be overcome by
scanning the object from different angles.
• A disadvantage is the time needed to obtain measure-
ments is greater than 4 minutes (de Sá Gomes et al.,
2019).
• Safety issues are important, such as exposure of eyes to
the laser beam, particularly in growing children (Kara-
tas and Toy, 2014).
• Laser scans are sensitive to light and metal objects,
requiring careful control of the operating environ-
ment, and the speed of data capture. This can make the
processes longer and less suitable for scanning younger
children (Halazonetis, 2001).
Optical surface scanning
This system is based on the principle of triangulation and
utilizes a 3D optical scanning system. The rotary optical
system produces a beam of light that is fanned into a vertical
line of 0.7mm width by a lens, and projected onto the face.
Optical surface scanning of soft tissues allows the three-
dimensional study of the face which is not possible with
cephalograms.
The accuracy of this system greater than 0.5mm, but repro-
ducibility needs further assessment (Coward et al., 1997).
The optical surface scanner has the advantage of rapid and
accurate data in all three dimensions (Nute and Moss, 2000).
Moreover, the lack of ionizing radiation allows data to be ac-
quired of for research without the risks of ionizing radiation.
However, the major disadvantage of the system is its cost. It
also has limitations in capturing undercuts in impressions,
and these scans would not form a consistently reliable bases
for routine orthodontic diagnostics and treatment planning.
Structured light imaging
The principle of this system is the projection of a pattern of
light (for example lines, strips) onto a surface analysis of the
image distortion of light results in a the three-dimensional
surface map. Images are captured from one viewpoint, so
multiple images are taken to obtain frontal, left, and right
views of a face. A full-face model is then produced by com-
bining different perspectives to reproduce one model by a
process called stitching, which can be performed manually
or semi-automatically. The disadvantages of this system are
long required time and the manual intervention.
Magnetic resonance imaging and orthodontics
MRI image is produced by radio waves directed at a patient
placed in a magnetic field. MRI creates an image without us-
ing ionizing radiation and records soft tissues in high detail,
A disadvantage of MRI is the length of time required for
scanning. Some patients are unable to tolerate the long
scanning time of the enclosed scanning space for the dura-
tion of the scan. Hence, MRI is contraindicated in patients
with claustrophobia and those with ferromagnetic implants.
Furthermore, MRI does not provide good bone details and
the metallic objects appear black (Dahllöf and Huggare,
2004). Evidence that suggests that orthodontic stainless steel
appliances can cause artefacts, hence, removal of stainless
steel orthodontic appliances prior to MRI scan is recom-
mended, especially if the area of interest is near oral cavity,
however, ceramic brackets cause no distortion to the MR
image (Beau et al., 2015). Multistranded stainless steel lin-
gual retainers did not cause significant image distortions in
MR images (Zhylich et al., 2017).
Advantages of MRI
The major advantages include:
• Non-ionizing radiations.
• Easy to reconstruct images in any plane with an excel-
lent soft tissue discrimination, and non-dependency on
the operator.
• MRI is used for upper airway analysis and measur-
ing airway space especially in patients with a cleft to
determine velopharyngeal incompetence (Kuijpers et
al., 2014a).
• MRI is the gold standard for imaging of TMJ morphol-
ogy but mostly reserved for those patients with persis-
tent symptoms following conservative treatment where
surgical intervention is being considered.
• MRI allows examination of inflammatory processes and
scar tissues.
• MRI can be safely used in patients allergic to contrast
agent.
• A recent study indicated that MRI enables reliable 3D
cephalometric analysis with excellent agreement to cor-
responding measurements on CBCT. Thus, MRI could
serve as a non-ionizing alternative to CBCT for treat-
ment planning and monitoring in orthodontic treat-
ment as well as oral and maxillofacial surgery (Juerchott

et al., 2020).
Imaging of the temporomandibular joint
These include CT scan, CBCT scan and MRI for a disc prob-
lem. As previously stated, conventional radiographs are no
longer recommended for investigating TMJ pain dysfunc-
tion. The need to have radiographs taken in advance of treat-
ment in order to avoid possible later claims of negligence
cannot be justified.
Exam Night Review
• Pregnancy---<1mSv, <150 Rg/Wk—IRMER 2000
• No Thyroid collars/ Lead Aprons is needed---IRR99
• 2 meters distance from Primary Beam---IRR99
• Storage of radiographs: BDA- 11yrs or till 25th Birth-
day, whichever longer
• Natural background radiation is estimated to be about
0.08 mSv per day
• CBCT is about 3 to 6 times the Xray dose of digital
panoramic radiograph and 15 to 26 times the dose of
lateral cephalometry (Signorelli et al., 2016).
• Accuracy of parallax: Horizontal parallax 83% v/s verti-
cal parallax 68% (Armstrong et al., 2003)
Types of errors in cephalometry
• Systemic error.
• Random error: Projection, identification & measuring
system.
Stable references planes / point
• Anterior cranial base- De Coster’s line and Björk’s
structural method.
• Maxilla: Key ridge area (anterior surface of the zygo-
matic process) by Björk, Superior & inferior surface of
the hard palate.
• Mandible: Anterior contour of the chin, Inner contour
of the symphysis, distinct trabecular structures in the
symphysis, contour of the mandibular canal, lower con-
tour of a mineralized tooth germ of 3rd molar.
• Artificial structure – implants.
• Template analysis- Pitchfork, Pancherz & Bolton’s tem-
plate analysis.
Cone Beam Computed Tomography (CBCT)
• Cone beam shaped radiation with less Xray dose when
compared to CT scans, however higher Xray dose than
conventional radiographs.
• Should be used cautiously and only when indicated.
Justification of benefits of increased dose for improving
diagnosis and treatment planning and when 2D cannot
provide the relevant information.
• Use of small FOV’s highly recommended.
• Overall effective dose between 50 - 500 μSv.
• Uses in orthodontics for impacted teeth, root resorp-
tion, dental anomalies, CLP & CP, orthognathic surgery
& airway assessment.
Hand wrist radiographs: Are no longer recommended.
Radionucleotide imaging: With Technetium 99 scan.
Non-ionizing imaging
• 2D digital photography.
• Intraoral scanning.
• Digital models.
• Stereophotogrammetry.
• Laser scanning.
• Optical surface scanning.
• Structured light imaging.
• Magnetic resonance imaging.
Available evidence
• Digital radiographical imaging is more environmentally
friendly as less processing chemicals and reusable plates
are used (Brennan, 2002).
• Horizontal parallax is more sensitive in detecting
impacted canine 83% when compared to 68% vertical
parallax as assessed by dentists (Armstrong et al., 2003).
• Cephalometric tracing can be done manually or digi-
tally. Studies have shown there is minimal difference
between the two types of tracing methods
• Surface-based and voxel-based superimposition
methods using the anterior cranial base as a reference
structure in 3D were accurate and reliable in detecting
changes in landmark positions when superimposing.
• Low-dose protocols for CBCT imaging: Dose reduction
is usually achieved by mAs reduction, use of partial ro-
tations, reduced number of projections, and larger voxel
sizes, but seldom by kV reduction.
• Current available evidence suggests that CBCTs could
be reliable to detect the presence of ERR in clinical
practice and has higher diagnostic efficacy than periapi-
cal radiographs. (Yi et al., 2017)

26
• No evidence that CBCT improves outcomes of treat-
ment.
• For diagnostic purposes and short-span scanning, the
accuracy of intraoral scanner systems is comparable to
the accuracy of conventional impressions
• A systematic review suggested that digital models are as
reliable as traditional plaster models, with high accura-
cy, reliability, and reproducibility. Landmark identifica-
tion, rather than the measuring device or the software,
appears to be the greatest source of error. Furthermore,
with their advantages in terms of cost, time, and space
required, digital models could be considered the new
gold standard in current practice (Fleming et al., 2011)
(Martin et al., 2015, De Luca Canto et al., 2015)
• 3D photogrammetry measurements relating the jaws to
each other and incisor orientation has a strong positive
correlation with corresponding traditional cephalo-
metric measurements and can serve as cephalometric
predictors
• Stereophotogrammetry was found to a reliable and
accurate tool for the morphological evaluation of soft
tissue in comparison to 2D imaging and laser scanning
• Laser scanner and stereophotogrammetry are reliable
soft tissue imaging systems with a maximum measure-
ment error of <1mm (Kuijpers et al., 2014a)
• A recent study indicated that MRI enables reliable 3D
cephalometric analysis with excellent agreement to cor-
responding measurements on CBCT. MRI could serve
as a non-ionizing alternative to CBCT for treatment
planning and monitoring in orthodontics as well as oral
and maxillofacial surgery.
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3
1. History
2. Equipments
3. Clinical stages in taking a cephalogram
4. Uses of cephalometry
5. Requirements of cephalometric measurement
6. Common cephalometric landmarks
7. Cephalometric lines for skeletal analysis
8. Cephalometric lines for dental analysis
9. Cephalometric measurement for profile analysis
10. Cephalometric analysis techniques
11. Key cephalometric analysis
In this Chapter
Cephalometric In
Orthodontics
Written by: Mohammed Almuzian, Haris Khan, Syed A. A. Bukhari, Aroosh Ahmed, Khaula Ashfaq

Cephalometric In Orthodontics
32
The term cephalometric came from Latin meaning ‘mea-
surement of the head’. The conventional meaning of cepha-
lometric is ‘using a standardised skull radiograph to assess
facial, dental, skeletal relationships and airway analysis.
Cephalometric is a 2 dimensional image of a 3 dimensional
object. Cephalometric evaluation is integral to orthodontics
and used for assessment, diagnosis and treatment planning
of the orthodontic patient.
History
Cephalometric machine was developed in the 1930’s by
Broadbent (USA) and Hofrath (Germany) and used for
growth studies (Broadbent, 1937). Originally postero-ante-
rior and lateral views were recommended to allow 3-dimen-
sional assessment (Broadbent, 1937).
Equipments
These include:
• Cephalostat or craniostat: It is used to position the
patient’s head in the machine, hence, it is a stabilizing
apparatus with ear rods. It also contains the cassette
holder and film.
• Cassette: It usually contains rare earth intensifying
screens and indirect action film. The dimension is usu-
ally 18 x 24 cm. It is placed 45 to 55 cm (1.5 to 1.8 feet)
behind the mid-sagittal plane of the patient. The greater
the distance from the mid-sagittal plane, the greater the
magnification error.
• X-ray generating apparatus: The x-ray source is in a
fixed position relative to the cephalostat and the film.
Therefore, successive radiographs are standardized and
can be compared by superimpostion without magnifi-
cation error. The x-ray source should be 120-150cm (5
feet) away from the mid-sagittal plane of the patient.
Collimation of the x-rays occurs through the use of a
triangular collimator. This limits exposure to the pa-
tient’s cranial base and facial skeleton.
• Aluminum wedge filter: It has a specific design in
order to attenuate the x-ray beam selectively in the
soft tissue region. The wedge filter enhances soft tissue
visibility on the film. The wedge filter is either attached
to the tube head or the cepalostat, hence, positioned
between the patient and the anterior part of the cassette.
Clinical stages in taking a cephalogram
The patient is positioned in the cephalostat in natural head
position (NHP). NHP is a physiological and reproduc-
ible position, in which the patient usually positions their
head. NHP can be reproduced within 1 or 2 degrees. NHP
is affected by audio-visual reflex, skeletal pattern (in Class
II cases the patients may tip their head up), growth pattern
(posterior rotation can result in the mandible flexing caus-
ing the head to tip down) and respiratory pattern (in order
to increase airway patency patients may tip their head up).
There are two methods of attaining NHP:
1. Crude method: Patient is relaxed and looks at a distant
object on the horizon.
2. Sensory method: Patient looks at their own eyes in a
mirror, and moves their head up and down in increas-
ingly smaller movements until they feel they are in a
comfortable position.
Sometimes the Frankfort plane is used to help orientate the
patient in NHP, by keeping the Frankfort plane parallel to
the floor. However, the Frankfort plane is an anatomical
position and therefore might not be reproducible for the
patient.
Uses of cephalometry
These include:
1. Diagnosis and treatment planning including:
• Assessment of sagittal and vertical skeletal relation-
ships.
• Assessment of incisor inclination and position.
• Assessment of soft tissue profile.
• Orthognathic surgery planning and VTO (visual
treatment objectives).
• Helping in detection and localization of unerupted
teeth or pathology.
2. During active treatment including:
• Assessment of skeletal and dental relationships post-
functional therapy.
• Assessment of incisor position, to plan mechanics of
space closure and anchorage demands.
• In orthognathic surgery cases for surgical planning,
as well as post-operatively to assess surgical changes.
3. End of treatment including:
• Assessment of dental arch relationship.
• Planning retention according to treatment changes.
• Baseline records to monitor changes in post-reten-
tion phase (Björk, 1954).
• Determining the reasons for relapse and unfavour-
able growth, especially in orthognathic surgery cas-
es.
4. Research purposes (Bjork and Palling, 1955, Bjork, 1955)
Is lateral cephalometry essential for treatment planning?
This is a very debatable topic in which the clinician skills

Cephalometric In Orthodontics 33
and philosophy have significant impact. Generally, the use of
cephalograms depends on the clinician’s experience, prefer-
ences and the severity of cases.
It was concluded in one study that only 4-20 % of treatment
plans could have changed in the presence of cephalometric
analysis (Bruks et al., 1999). Another study showed that
cephalometric analysis is not an essential requirement for
orthodontic treatment planning, as it did not influence treat-
ment planning decisions for patients with Class II malocclu-
sions (Nijkamp et al., 2008).
Requirements of cephalometric measurement
These include:
• Reliable.
• Reproducible.
• Accurate.
• Easy.
• Accessible and cheap.
• Use of stable reference points.
• Not be affected by patient size or age.
Common cephalometric landmarks
These include:
• Sella (S): Midpoint of the sella turcica (pituitary fossa).
• Porion (Po): Most posterior and superior point on the
external auditory meatus.
• Condylion (Cd): The most posterior and superior point
on the mandibular condyle.
• Nasion (N): The most anterior point on the frontonasal
suture in the midline, while soft tissue Nasion (Van
Leeuwen et al.) is the most prominent point on the soft
tissue in front of Nasion point.
• Anterior nasal spine (ANS): The tip of the anterior nasal
spine in the midline.
• Posterior nasal spine (PNS): The tip of the posterior
nasal spine in the midline.
• Articulare point (Ar): Point on intersection of poste-
rior cranial base and posterior border of the ascending
ramus.
• Basion (Ba): The most anterior inferior point of the
foramen magnum.
• Orbitale (Or): The most inferior and anterior point on
the orbital margin.
• Gnathion (Gn): The most anterior and inferior point on
the bony chin.
• Menton (Me): The most inferior point of the mandibu-
lar symphysis in the midline, while soft tissue Menton
(Me’) is the lowest point on the contour of the soft tissue
chin.
• Gonion (Go): The most posterior and inferior point on
the angle of the mandible.
• Pogonion (Pog): The most anterior point on the bony
chin, while soft tissue Pogonion (Pog’) is the most
prominent point on the soft tissue chin.
• Point A (subspinale): This is the deepest point on the
curved contour of the bony maxilla between the ante-
rior nasal spine and alveolar crest.
• Point B (supramentale): This is the deepest point on the
curved contour of the mandible between the chin and
alveolar crest.
• Molar superioris (Ms): The mesial cusp tip of the upper
first molar.
• Molar inferioris (Mi): The mesial cusp tip of the lower
first molar.
• Incisor superius (Is): Tip of the crown of the most ante-
rior upper central incisor.
• Upper incisor apex (Banerjee et al.): The root apex of
the most anterior upper central incisor.
• Incisor inferius (Guyer et al.): Tip of the crown of the
most anterior lower central incisor.
• Lower incisor apex (LIA): The root apex of the most
anterior lower central incisor.
• Glabella (G): Mid-brow area, and taken as the most
prominent point on the forehead in the mid-sagittal
plane.
• Pronasale (P): The most prominent anterior part of the
nose tip.
• Subnasale (Sn): Junction between the beginning of the
upper lip and lower border of the nose in the mid-
sagittal plane.
• Labrale superius (LS): The most prominent point on
the maximum convexity of the vermillion border of the
upper lip in the mid-sagittal plane.
• Labrale inferius (LI): The most prominent point at the
maximum convexity of the vermillion border of the
lower lip in the mid-sagittal plane.
Cephalometric lines for skeletal analysis
These include:
• Frankfort horizontal line / plane: A line constructed
from porion to orbitale. Another way to construct the
Frankfort line is simply to draw it at a specific inclina-

34
tion to SN, usually 6 degrees. The inclination of SN to
the true horizontal plane (or to the Frankfort plane
if true horizontal plane is not known) should always
be noted, and if the inclination of SN is more than 8
degrees, any measurements based on SN should be
corrected by this difference. The drawbacks in using of
Frankfort horizontal line include that both porion and
orbitale are bilateral structures which frequently do not
coincide and therefore have to be averaged. They are
also difficult to locate in some cases.
• Sella-nasion line / plane: The line is constructed from
sella to nasion, and represents the anterior cranial base.
The benefits of Sella-Nasion line are the ease to locate
both Sella and Nasion points lie in the midsagittal
plane. Sella-nasion line is useful in assessing the vertical
jaw relationship, correction of the Frankfurt plane, in
evaluating the inclination of upper incisors to the cra-
nial base and it can be used as a stable reference point
on the cranial base for superimposition. The weaknesses
of Sella-Nasion line include that the Sella point can alter
during early growth and that the Nasion can be sub-
jected to both horizontal and vertical growth changes/
variations.
• Maxillary line / plane: It is a line connecting the anterior
nasal spine and the posterior nasal spine. The Maxillary
line is used to assess the relationship between Maxilla to
Frankfort plane, to SN plane, to mandible as well as the
inclination of upper incisors to the maxillary skeletal
base. The line can be used for maxillary superimposi-
tion.
• Mandibular line / plane: It can be constructed (a) as a
line tangent to the lower border of the mandible and
Menton, as described by Tweed (Tweed, 1946, Tweed,
1954), Wylie (Wylie, 1947) and Ricketts (Ricketts, 1960,
Ricketts, 1961). Other described it as a line connecting
Gonion to Gnathion, as described by Steiner (Steiner,
1953) or as as a line connecting Gonion to Menton, as
described in the Eastman analysis (Mills, 1970).
• The Mandibular line is used to assess the relationship
between vertical jaw relationship, mandibular to Frank-
fort plane, to SN plane, to maxillary line as well as the
inclination of lower incisors to mandibular plane. It can
be also used for mandibular superimposition.
Cephalometric lines for dental analysis
These include:
• Anatomical occlusal plane connecting the tip of lower
incisor edges to the midpoint between the upper and
lower first permanent molar cusps. It is used in the
Bjork analysis (Bjork, 1947, Björk, 1954).
• Functional occlusal plane is the line joining the mid-
point of the overlap of the mesio-buccal cusps of the
first molars and the buccal cusps of the premolars or
deciduous molars. It is used by Ricketts (Ricketts, 1960,
Ricketts, 1961) and in the Wits analysis (Jacobson,
1975).
• Bisecting occlusal plane/ line: A line joining the mid-
point of the overlap of the mesio-buccal cusps of the
upper and lower first molars with the point bisecting
the overbite of the incisors. It is used by Downs (Downs,
1948, Downs, 1952) and Steiner (Steiner, 1953).
Cephalometric measurements for profile analysis
These include:
• Soft tissue Nasion to Frankfort horizontal plane: By
using this technique a vertical line is drawn from soft
tissue Nasion perpendicular to Frankfort horizontal.
Subnasale or soft tissue point A should be approxi-
mately 2-3 mm in front of this line, and the soft tissue
Pogonion should lie 2 mm behind this facial plane.
• Facial vertical or Meridian line was developed by
Gonzales-Ulloa (Gonzalez-Ulloa, 1962, González-Ulloa
and Stevens, 1968), by dropping a line from soft tissue
Nasion, perpendicular to true horizontal line with the
patient in natural head position. Subnasale should lie on
this line while soft tissue pogonion should be 0 ± 2 mm
to this line.
• Bass aesthetic analysis (Bass, 2003): In this analysis a
perpendicular line is dropped from Subnasale with the
patient in NHP.
• Z angle (Merrifield, 1966): It is formed by the intersec-
tion of the tangent to the chin and vermilion border of
most prominent lip and Frankfurt horizontal, normal
value range is at 80˚+9˚. It is also called the “Profile line
of Merrifield”.
• Profile angle is the angle of convexity as described by
Burstone. This angle formed between a line from soft
tissue glabella to subnasale, and from subnasale to soft
tissue pogonion. It represents the total facial angle and
range from 165˚ -175˚.
• Powell analysis involves a combination of nasofrontal
angle, nasofacial angle, nasomental angle, and mento-
cervical angle. It has been developed to give insight into
an ideal facial profile.
Cephalometric measurements for lip analysis
These include:
• Esthetic line (E-line) (Ricketts): It connects the nasal tip
(pronasale) to soft tissue pogonion. In adults, the upper
lip should be 4mm behind this line while the lower lip
should be 2 mm behind this line. The assessment of
lips using the E line is dependent on the nose and chin

projection.
• Steiner line (S-line): It connects soft tissue pogonion to
the midpoint between subnasale and the nasal tip. The
lips should touch this line.
• Harmony line (H-angle): The H-angle is formed by a
line tangent to the chin and upper lip with the NB line.
Holdaway stated that in balanaced, H-angle should be
within the range of 7° to 15°, which is dictated by the
patient’s skeletal convex¬ity. The ideal position of the
lower lip to the H line is 0 to 0.5 mm anterior. Ideally
this line should bisect the nose.
Cephalometric measurement for labionasal analysis
Nasolabial angle (NLA) is formed between the nasal colu-
mella and the upper lip. The average value is 90˚–110˚. It
can be divided by true horizontal at subnasale point into
two angles (upper one represents the nasal angulation of an
average 28˚, and the lower angle represents the upper lip
angulation of average 85 ˚). NLA depends on:
• Anteroposterior position of upper incisors.
• Anteroposterior position of the maxilla.
• The morphology of the upper lip.
• The vertical position of the nasal tip.
• Columella position and orientation.
Cephalometric measurement for labio-mental analysis
Labiomental angle is the angle formed between the lines
from lower lip to soft tissue B point, and soft tissue B point
to soft tissue Menton. It is influenced by the incisor inclina-
tion and anterior lower face height. The average value is
110–130 degree. Excessively proclined lower incisor teeth,
a prominent chin and a reduced lower anterior facial height
may lead to an acute labiomental angle.
Cephalometric analysis techniques
They can be classified into analysis that:
1. Solely describe disharmony such as
• Down’s technique
• Steiner technique
• Ricketts technique
• Harvold technique
• McNamara technique
• Sassouni technique
• Wits technique
• Wylie technique
• Tweed technique
2. Designed for treatment planning such as Ballard con-
version technique
3. Analysis of change in growth and treatment such as
• Pancherz technique
• Pitchfork technique
• Bolton (Template analysis)
4. Research purposes such as Bjork technique
Key cephalometric analysis
1. Sagittal analysis such as:
• SNA: The anteroposterior position of the maxilla is as-
sessed by measuring the angle formed between the lines
SN and NA.
• SNB: The anteroposterior position of the mandible is as-
sessed by measuring the angle formed between the lines
SN and NB.
• ANB: The difference between SNA and SNB angles de-
fines the anteroposterior relationship between the max-
illa and mandible.
• However, it is important to notice that both points A and
B do not represent the true anterior extent of the skeletal
bases.
Factors affecting the ANB angle
These include:
• Cranial base length.
• Cranial base orientation.
• A and B points can be changed due to bone remodelling
that occurs during the orthodontic movement of the
upper and lower incisor teeth.
• Jaw orientation.
• Facial height.
Ballard cephalometric analysis
This analysis is used to assess the anteroposterior jaw posi-
tion through measuring the cephalometric overjet (Ballard,
1951). The inclination of the incisors is decompensated to
the normal values, and then the overjet is measured. The
normal value of the upper incisor to the maxillary plane is
109˚, and the lower incisor to the mandibular plane is 93˚.
But for Ballard conversion, the value of the lower incisors is
calculated by subtracting the maxillary–mandibular plane
angle (MMPA) from 120°. In order to perform Ballard
conversion: (a) Trace on a separate piece of tracing paper the
outline of the maxilla, the mandibular symphysis, the inci-
sors and the maxillary and mandibular planes, (b) mark the
‘rotation points’ of the incisors one-third of the root length
away from the root apex, (c) by rotating around the point

36
marked, reposition the upper incisor at an angle of 109° to
the maxillary plane and repeat the same for the lower inci-
sor taking in consideration the adjusted value based on the
MMPA value.
Interpretations of Ballard conversion
These include:
• Mild skeletal 2: Lower incisors occlude behind the
cingulum plateau but not posterior to the upper incisor
tooth.
• Severe skeletal 2: Lower incisors occlude behind the cin-
gulum plateau and posterior to the upper incisor tooth.
• Mild skeletal 3: Lower incisors occlude anterior to up-
per cingulum plateau and positive overjet.
• Severe skeletal 3: Lower incisors occlude anterior to up-
per cingulum plateau and reverse overjet.
Weaknesses of Ballard conversion
It relies on the basis that upper and lower incisors have an
average inclination to the cranial base. It also relies on the
fact that the centre of resistance being one third from the
apex, and incisors rotate around this point, which is not true
in all cases
Sassouni analysis
This analysis uses five horizontal anatomic planes:
• The inclination of the anterior cranial base.
• Frankfort plane.
• Palatal plane.
• Occlusal plane.
• Mandibular plane.
Sassouni evaluated the anteroposterior position of the face
and dentition by using the above planes and constructing
various arcs intersecting them.
Interpretation of Sassouni analysis
These include:
• Well-proportioned faces: The planes converge towards a
single point and the anterior nasal spine, the maxillary
incisor, and the bony chin should be located along the
same arc.
• Short face: If the planes intersect posterior to the occipi-
tal bone it means the patient has a short face / skeletal
deep bite).
Wits analysis by Jacobson The Wits analysis was conceived
primarily as a way to overcome the limitations of ANB as
an indicator of jaw discrepancy. (Jacobson, 1975, Jacobson,
1976). It is based on the vertical projection of points A and B
onto the functional occlusal plane (AO and BO), where the
horizontal difference between these points is subsequently
measured. The Wits analysis is influenced by tooth position
and movement as point A and B are subject to remodelling
depending on incisor position. This can affect the horizonal
and vertical position of A and B points. The weakness of
the Wits appraisal is the difficulty to construct the occlusal
plane which significantly affect the outcome measurement.
If there is a clockwise rotation of the occlusal plane, AO will
be behind BO. If there is a counter clockwise rotation of the
occlusal plane, BO will be ahead of AO, and not represent
the anteroposterior discrepancy. Some important points of
the Wits appraisal is given in table 1.
Table1: Wits analysis Jacobson (1975)
Males BO should lie 1mm ahead
of AO
Females AO should coincide with
BO
Skeletal Class II malocclu-
sion
AO should lie ahead of BO
Skeletal Class III malocclu-
sion
BO lies ahead of AO
Harvold Analysis
It describes the severity and degree of jaw disharmony by
measuring the unit lengths of the mandible (Condylion-
Pog) and the maxilla (Condylion-ANS), and comparing the
difference between them (Table 2) (Harvold, 1974). The dif-
ference between these numbers provides an indication of the
size discrepancy between the jaws. The vertical assessment is
made via ANS-Me. It must be kept in mind that the shorter
the vertical distance between the maxilla and mandible, the
more anteriorly the chin will be placed for any given unit
difference, and vice versa
Downs analysis
It is one of the earliest analyses which comprised of both
skeletal and dental components in the presence of normal
occlusion .Frankfort plane is used as a reference. Downs
study (Downs, 1948, Downs, 1952, Downs, 1956) was based
on 20 Caucasian boys and girls, aged 12-17 years with excel-
lent facial and occlusal balance (Table 3 & 4).

Table 2: Harvold Analysis
Variables Purpose Male Female
Maxillary length Measure the distance from the anterior bor-
der of the mandibular condyle to the anterior
nasal spine
Mean values with age
Age mm
6
9
12
14
16
82
87
92
96
100
Mean values with age
Age mm
6
9
12
14
16
80
85
90
92
93
Mandibular length Measure the distance from the same point to
the anterior point of the chin (Pog)
Age mm
6
9
12
14
16
99
107
114
121
127
Age mm
6
9
12
14
16
97
105
113
117
119
Lower face height Measure the distance from the Anterior nasal
spine to Menton
Age mm
6
9
12
14
16
59
62
64
68
71
Age mm
6
9
12
14
16
57
60
62
64
65
Table 3: Downs analysis skeletal component
Skeletal compo-
nent
Description Range
1 Facial angle Angle formed between the Facial plane (N-
Pog) and Frankfort plane
87.8 °
(±3.6)
Measures the degree of protusion or
retrusion of the chin
2 Angle of convexity Angle formed between the lines Nasion to
point A & point A to Pogonion
0°
(±5.09)
Measures maxillary protusion in relation
to the total profile.
3 A-B plane Angle formed between the Facial plane (N-
Pog) & Point A to Point B
-4.6°
(±3.67)
Measures the anterior limit of the denti-
tion in relation to facial profile
4 FMPA Angle between Frankfort plane and man-
dibular plane
21.9°
(±3.24)
Measures the vertical growth. If the
angle increases that means the person is
a vertical grower as the mandible shifts
downward.
5 Y axis Angle formed between line extending from
S-Gn and the Frankfort plane
Check this – is it not the angle between SN
and S-D point in the middle of the symphy-
sis?
59.4°
(±3.82)
Measures the direction of facial growth. If
angle is increasing (Class III) that means
the greater vertical growth of mandible
and if angle is decreasing (Class II) that
means greater horizontal growth of
mandible

38
Table 4. Downs analysis dental component
Dental component Description Range
1 Cant of occlusal plane to
Frankfort plane
Angle formed between the occlusal plane and
Frankfort plane
9.3°
(±8.3)
Measures the slope of oc-
clusal plane
2 Interincisal angle Angle formed by a line passing through the incisal
edge and the apex of the root of the upper and
lower central incisors
135.4°
(±5.76)
This angle is decreased in
Class I bimaxillary pro-
trusion and Class II Div
1 cases and increased in
Class II Div 2 cases
3 Lower incisor-occlusal plane Angle formed between the long axis of the lower
central incisor and the occlusal plane need to
elaborate on this angle. This is not clear
14.5°
(±3.48)
Increased angle tells us
that the lower incisor is
proclined
4 Lower incisor-mandibular
plane
Angle formed between the long axis of the lower
central incisor and the mandibular plane need to
elaborate on this angle. This is not clear
1.4°
(±3.78)
Tells us about the procli-
nation or retroclination
of the lower incisors
5 Upper incisor to A-Pog Linear measurement. Line drawn from A-Pog and
the distance from labial surface of upper incisor
measured to this line need to elaborate on the
constructed line. This is not clear
2.7mm
(±1.8)
Tells us about the procli-
nation or retroclination
of the upper incisors
Downs analysis can be easily presented by plotting the
results on a two-polygon graph or wiggleogram, in which
one displayed the skeletal pattern and the other the dental
pattern. The main advantage of a Wiggleogram is that it is a
rapid quantitative and qualitative analysis. The centre of the
graph showed the average values of each pattern, while the
lateral part showed the extreme values.
Eastman analysis (Mills, 1982)
Eastman analysis variables and norms are:
AP variables including:
• SNA: 81 (± 3)°.
• SNB: 78 (± 3) °.
• ANB: (3 ± 2°) + Mills correction.
Vertical variables including:
• SN-MxP= 8 (± 3)°.
• MMPA= 27 (± 5)°.
• FMPA 27= (± 5)°.
Dental variables including:
• SN-UI = SNA.
• UI-MxP= 109 (± 6)°.
• LI-MP= 93 (± 6)°.
Mills’ Eastman correction (Mills, 1970)
When relating the maxilla and mandible to the cranial base,
any deviation in the cranial base could affect the jaw rela-
tionship and the ANB angle, for example: the more anterior
and / or superior the position of nasion, the lower the SNA
angle. The more posterior and / or inferior the position of
the nasion, the greater the SNA angle. Mills therefore intro-
duced a correction for this problem:
• For every degree SNA is greater than 81, subtract 0.5
from the original ANB value.
• For every degree SNA is less than 81, add 0.5 from the
original ANB value.
The vertical position of Sella does not alter the ANB as it
affects the SNA and SNB angle to the same extent. To apply
Eastman correction, SN-maxillary plane angle should be 8°±
3°.
Limitations of the Eastman correction
These include overestimation of the correction of ANB
values when N is posterior. As N moved anteriorly, the East-
man correction overestimated the Class III skeletal relation-
ship (Kamaluddin et al., 2012).
Steiner analysis
Steiner analysis was proposed by Cecil Steiner (Steiner,
1953). The SN plane (from Sella to Nasion) is used as a
horizontal reference plane. SN plane is used as both S and
N can be easily located on the cephalometric radiograph
because these points are located in the mid sagittal plane of
the cranium. The skeletal and dental analysis of the Steiner
analysis are shown in table 5.
Table 5. Steiner analysis

Skeletal analysis
SNA 82°
SNB 80°
ANB 2°
SN-Mandibular plane 32°
Condyle to E point 25° ±4
Pog-L point 66° ±4
SN-Occlusal line 14.5°
Dental analysis
Upper first molar to NA 27mm
IMPA 93°
Inter incisal angle 130°
Lower first molar to NB 23 mm
U.I-NA distance 4mm
U.I-NA angle 22°
L.I-NB distance 4mm
L.I-NB angle 25°
Steiner also pointed out acceptable compromises in ANB
angle which he called Steiner sticks or chevrons.
Limitations of Steiner analysis
These include (Abdullah et al., 2006):
• It is difficult to rely on the ANB angle as it is influenced
by the vertical height of the face. If the vertical distances
between Nasion and points A and B increased, the ANB
angle decrease and vice versa.
• If the anteroposterior position of Nasion is abnormal, it
will change ANB value. One of the reasons for the birth
of Wits analysis was to overcome this drawback.
Ricketts analysis
It is a profile orientated analysis. It includes an aesthetic
plane and other variables similar to Downs’ analysis (Rick-
etts, 1960, Ricketts, 1961) .
McNamara analysis
The McNamara analysis combines elements of previous
analyses (Ricketts and Harvold). Both Frankfort plane and
Basion-Nasion lines are used as reference planes (McNama-
ra, 1984). This analysis evaluates the position of the denti-
tion and jaws relative to each other, and to the cranial base.
The McNamara analysis includes:
• Anteroposterior skeletal base relationships relative
to the cranial base: The relationship of the maxilla to
cranial base can be assessed a vertical line extend-
ing downwards from Nasion, perpendicular to the
Frankfort plane. The maxilla (point A) should be on or
slightly ahead of this line (0-1 mm). The relationship of
the mandible to cranial base is assessed using a vertical
line extending downward from Nasion perpendicular to
the Frankfort plane. The mandible (point Pog) should
be slightly back of this line (–2 to –4 mm).
• Anteroposterior skeletal base relationships unit mea-
surements including: maxilla length unit measured
from Co–A point, mandibular length unit measured
from Co–Gn and the difference between these numbers
provides an indication of the size discrepancy between
the skeletal bases.
• Vertical skeletal assessment including lower face height
(ANS-Me), FMPA (Adults 22° while mixed dentition
25°)and facial axis (90°).
• Dental relationships including upper incisor (the facial
surface of the upper incisor is assessed relative to a per-
pendicular line through point A, the average is 4-6mm)
and lower incisor (the facial surface of the lower incisor
is assessed relative to the A-Pogonion line, as in the
Ricketts analysis).
• Airway space including upper pharyngeal width (<5
mm) and lower pharyngeal width (10–12 mm).
Tweed analysis
It was introduced by C. H. Tweed in 1946. It establishes the
prognosis of treatment on the basis of the Tweed triangle,
which is formed by the FMPA and lower incisor axis planes
(Tweed, 1946, Tweed, 1954). A Frankfort mandibular inci-
sor angle (FMIA) of 65-70° is considered ideal for good
aesthetic outcomes. The lower incisor angle is adjusted to
achieve the ideal FMIA and treatment is planned to achieve
this. The analysis has been used as a total analysis by some,
even though Tweed stressed it was intended only as a treat-
ment aid. The validity of the total analysis of Tweed triangle
has not been proven.
2. Bjork analysis
This analysis involves over 90 measurements and it is re-
search orientated (Bjork, 1947, Björk, 1954). The analysis is
based on the polygon N-S-Ar-Go-Gn using the three angles:
Saddle angle (N-S-Ar), Articular angle (S-Ar-Go) and Go-
nial angle (Ar-Go-Gn), and the linear measurements of the
sides of the polygon. The analysis also assesses the anterior
and posterior face height relationship ratio (PFH : AFH).
3. Bolton template analysis
The templates exist in two forms:
• Schematic templates: showing the changing position of
selected landmarks with age on a single template.
• Anatomical complete templates:This is particularly con-
venient for direct visual comparison of a patient with
the reference group, whilst accounting for age.

40
4. Pi analysis (Kumar et al., 2012)
The Pi analysis has been introduced as a new method to
assess the AP jaw relationship. It consists of two variables:
the Pi angle and the Pi linear measurement. It utilizes the
skeletal landmarks G and M points to represent the mandi-
ble and maxilla respectively. The advantage of these points is
they are not affected by local remodelling secondary to den-
tal movements, unlike points A and B. The reference plane
utilized in measuring the Pi analysis is the true horizontal,
a line perpendicular to the true vertical obtained in natural
head position (NHP). The mean values for the Pi angle are:
• Skeletal Class I: 3.40 (+2.04).
• Skeletal Class II: 8.94 (+3.16).
• Skeletal Class III: 23.57 (+1.61).
5. Pancherz analysis (Pancherz, 1982)
This analysis measures skeletal and dental treatment changes
of the mandible and maxilla by measuring linear changes
from a perpendicular plane at Sella to the occlusal line with
radiographs superimposed on the SN plane. The weakness
of this method is that it depends on maxillary structures and
the occlusal plane (OP), which are subject to change with
dento-alveolar movements.
6. Pitchfork analysis (Johnston, 1996)
This analysis involves superimposition of 2 or more lateral
cephalograms to measure dental and skeletal changes rela-
tive to the functional occlusal plane (OP). Dental changes
are measured relative to the basal bone of the jaws while
skeletal changes are measured relative to the anterior cranial
base.
Exam Night Review
CEPHALOMETRICS
• Term cephalometric comes from Latin and the literally
meaning ‘measurement of head’
• Cephalometrics ( branch of orthodontics) used for
assessment, diagnosis and treatment planning of the
orthodontic patient.
• Developed in 1930’s by Broadbent (USA) and Hofrath
(Germany)
Equipment
• Cephalostat or craniostat
• Cassette
• X-raapparatus
• Aluminum wedge filter
Clinical stages in taking a cephalogram.
Patient is positioned in the cephalostat in natural head posi-
tion (NHP).
NHP is a physiological and reproducible within 1 or 2 de-
grees. There are two methods of attaining NHP:
• Crude: Patient is relaxed and looks at a distant object
in the horizon.
• Sensory: Patient looks at their own eyes in a mirror
NHP is affected by:
• Audio-visual reflex.
• Skeletal pattern
• Growth pattern
• Respiratory pattern
Uses of cephalometry
• Diagnosis and treatment planning before com-
mencing treatment
• During active orthodontic treatment
• End or near end of treatment
• Research purposes

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Space Analysis In Orthodontics
42

4
1. Clinical application of space analysis.
2. Basic terminologies in space analysis
3. Permanent dentition space analysis
4. Advantages and disadvantages of RLSA
5. Mixed Dentition Space Analysis
6. Symmetry of the arch
7. Bolton analysis
8. Bolton ratios, malocclusion and gender
In this Chapter
Space Analysis In
Orthodontics
Written by: Mohammed Almuzian, Haris Khan, Ayesha Tariq, Hajira Arham, Amna Sabeeh Noor

44
Space analysis is the process of calculation of excess or
deficient space in both arches for correcting a malocclusion
(Proffit et al., 2012).
Clinical application of space analysis
These include:
• Diagnosis
• Treatment planning
• Planning of anchorage
• Planning the mechanics
• Analysis of space requirements
• Informed consent
Basic terminologies in space analysis
These include:
Arch perimeter: Distance from the mesial contact of the
first permanent molar to the mesial contact of the contralat-
eral permanent first molar (Ngan et al., 1999)
Arch width intermolar: Distance between the mesiobuc-
cal cusp tip of the first permanent molar to the mesiobuccal
cusp tip point of the contralateral first permanent molar
Arch width intercanine: Distance between the canine cusp
tip to the cusp tip of the contralateral canine
Arch Depth or Arch length:The distance from a line per-
pendicular to the line connecting the mesial surfaces of the
permanent first molars to the midpoint of central incisors.
Sometimes widest point of molars is used instead of mesial
surface.
Arch expansion: Widening of the dental arch.
Arch lengthening: Increase of arch length by posterior
teeth distalization or anterior proclination.
Study model analysis to assess space requirements
Study model analysis is either undertaken manually or with
the aid of a computer (Schirmer and Wiltshire, 1997) and it
includes three measurements:
1. Arch perimeter / space available assessment
• Segmental technique: The arch is divided into four
segments: two anterior segment; right and left (1-3),
and two posterior segment (3-6). A linear measure-
ment is made from 2 points of each segment.
• Stainless steel (SS) / brass wire technique: A piece
of dead-soft SS wire or a brass wire can be contoured
to the arch and measured.
2. Space required assessment
The space required represents the sum of the mesiodistal
widths of each tooth measured using vernier caliper or
dividers.
3. Discrepancy between the space available and required is
the quantified crowding or spacing in the arch. A posi-
tive sign is given for spacing and a negative sign is given
for crowding.
Permanent dentition space analysis
Royal London space planning/ RLSA
RLSA was developed by a team at Royal London Hospital
in London (Kirschen et al., 2000a, Kirschen et al., 2000b).
RLSA is a package of comprehensive tool to measure the
space requirements objectively. RLSA consists of two main
domains, space requirement and space provision.
Domain 1: Assessment of space requirement
This domain consists of six elements:
• Crowding or spacing
• Curve of Spee leveling
• Arch expansion
• Anteroposterior position of incisor
• Tooth angulation
• Tooth inclination
The first four elements affect space requirements significant-
ly while others contribute minimally.
Spacing and Crowding analysis include all teeth up to mesial
surface of 1st molars. The recommended method involves
using a transparent ruler over the occlusal of maligned teeth
parallel to the floor and as close as possible to the arch form
that represent the majority of the teeth to measure the space
available. The total mesiodistal width of each individual
tooth is measured, the sum of the individual tooth size is
subtracted from the arch perimeter to calculate the space
surplus or deficiency. Crowding of two adjacent teeth can
also be assessed by measuring the mesiodistal widths of two
teeth and comparing it to the combined space available over
the arch, however, this should not be performed on three
or more teeth as the discrepancy between chord and arc
increases. Chord is the distance measured in a straight line
and arc being the curvature of archform. Incisor that repre-
sent the archform should also be included in cephalometric
analysis and overjet measurement to avoid double counting.
Leveling of the curve of Spee (COS): COS represents the line
passing through the buccal cusps and the incisal edges from
distal of lower 1st molar to the most anterior tooth of each
quadrant. 2nd molars are not part of the COS as they are
often not fully erupted and may be aligned by tipping them
distally, therefore, not requiring any space creation. The
distance from the deepest point of the COS to the lower oc-

Space Analysis In Orthodontics 45
clusal plane denote the depth of the COS (DoCOS). Space is
required for leveling the COS though the amount of which
varies depending on the DoCOS.
Mathematically, to calculate the space required (SR) to
flattened the COS, the following equation is considered
(SR=(DoCOS/2)-0.5), hence, to flatten DoCOS of 3mm,
4mm and 5mm, it is essential to provide 1mm, 1.5mm
and 2mm of space respectively.
The amount of the space required to flatten the COS be-
come constant if the DoCOS is more than 5mm i.e. very
deep COS (more than 6mm) requires only 2mm of space.
Two considerations are important. First, space for occlu-
sal plane leveling should only be considered if the pre-
molars have not been marked as crowded, otherwise, it
will lead to double counting as needing space for both
relief of crowding and for leveling. Secondly, not all oc-
clusal planes need to be leveled, so, clinical judgment is
important.
Change in Arch width or Arch expansion/contraction
Ideally, the distance between mesiobuccal cusp tips of
upper first permanent molars should be at least 2mm
wider than the lower first permanent molars (Gill and
Naini, 2012). There is controversy in literature about the
amount of space provided by expansion of the maxillary
arch. It has been suggested that for every 1mm for overall
expansion of arch, 1mm of space is created, the reverse is
true for arch contraction. However, Lee and team con-
cluded that for every 1mm of posterior arch width ex-
pansion, there is 0.56mm of space creation (Lee, 1999).
The latest literature reported that for every 1mm of in-
creases in intermolar width, there is a reduction of
0.28mm of arch depth, which is equivalent to 0.56mm
decrease in arch perimeter. Hence, approximately 0.5
mm of space is remained for each 1 mm of expansion
(O’Higgins and Lee, 2000). Other suggested that a net of
0.7 mm of space is provided in premolar area for each 1
mm of expansion (Adkins et al., 1990). Moreover, it is
important to notice that the space created from an in-
dividual tooth expansion is negligible in space analysis.
Anteroposterior changes to Incisors
There are few principles that need to be understood befor
e applying this domain of space analysis. Generally, it is
acceptable that the aims of treatment determine the po-
sition of lower incisor whilst the upper incisor position
is usually determined by achieving an overjet of 2mm.
Overjet is measured with the mandible in retruded con-
tact position, both clinically and from lateral cephalo-
metric radiographs. 2mm of space is required for every
1mm of change in the overjet. It has been proposed that
based on the archform being rectangular, 1mm of labial
movement (increase in the arch depth through procli-
nation) will provide 2mm of relief of crowding. A more
realistic parabolic archform is considered average, and
more than 1mm of labial movement will be required to
create a space of 2mm.
Proclining incisors by arch lengthening include three
categories: changes in incisors anteroposterior position,
torque and inclination. This is because of the wagon
wheel effect, therefore, it is summative and not a linear
effect. A study in 1996 demonstrates the aforementioned
fact, and also the effect of arch depth and width on the
amount of space created by proclination of the incisors
(Steyn et al., 1996). The greater the intercanine widths
and the shallower canine arch depths (from canine to
mid-incisor point) mean greater incisors proclination is
required to relieve a given amount of crowding.
Change in angulation (second order bend)
Teeth that are vertically upright take less space than teeth
that are at the correct angulation, with excessively angu-
lated teeth take up more space. Approximately, 0.5mm of
space per tooth is required to change the angulation of
the teeth from upright to mesio-angular. This principle
mainly applied in maxillary incisors, canines and man-
dibular canines. In most cases increased angulation is not
required.
Change in Inclination (torque or third order bend)
Achieving a correct torque or inclination is essential for
stability, improved esthetics, ideal tooth contacts with
minimal spacing, and good buccal occlusion. 0.25mm of
space is needed for each 5 degrees of palatal root torque,
if incisors are of average-shaped. If only two teeth are
torqued palatally, then, a space of 0.5mm is required.
This principle is usually used for maxillary incisors only.
Lower incisors are not considered in this math unless se-
verely proclined, as their contact points are close to the
incisal edge. Incisor proclination is considered a summa-
tive effect of anteroposterior and inclination changes.
Molar Relationship
Three factors affect molar relationship:
• Distalizing buccal segments, e.g., with Headgear or
any other distalization appliance.
• Mesial movement of buccal segments secondary to
anchorage loss.
• Differential jaw growth.
When anteroposterior position of incisors has been taken
into account, molar relationship is expressed as the differ-
ence in required space for upper and lower arches (Gill and
Naini, 2012). If the molar relation is Class I with the absence
of a tooth size discrepancy, the upper and lower arches

46
would have a similar space requirement.
Domain 2: Utilisation or creation of space
Generally, space can be created by different way, remember
SPEED TRIAL:
• Stripping of teeth (interproximal reduction or slander-
ization)
• Proclination of teeth
• Extraction
• Expansion
• Distalisation of molar
• Torque changing
• Rotation and de-rotation
• Incremental/ differential growth (positive for advanc-
ing Class II, and negative for advancing class III with a
deterioration in arch relationship expected)
• Angulation changing
• Leeway space
The created space can be utilised by:
• Tooth enlargement or build-ups
• Space opening for prostheses
• Mesial change in molar
Advantages and disadvantages of RLSA
RLSA is a systematic method of analysis and treatment plan-
ning, considering the main factors with require or generate
space. Although the RLSA has been shown to be reliable and
valid its use has the following disadvantages:
• Does not account for vertical and transverse problems
• Does not significantly affect decision for treatment
planning
• Tends to overestimate crowding
• Tends to drive treatment plan towards extractions
Is Royal London Space Analysis Reliable and does it influ-
ence orthodontic treatment decisions?
Dr Al-Abdallah in her study found that (Al-Abdallah et al.,
2008):
• RLSA is reliable.
• RLSA did not influence treatment decision.
• RLSA may have an influence on visual perception.
• RLSA does not have an impact on judgmental variation.
Other Methods for Space Analysis in Permanent Dentition
These include:
• Eye balling: It is a subjective inaccurate method to as-
sess crowding.
• Visual Method: as mentioned in RLSA which is associ-
ated with some disadvantages such as being not repro-
ducible, overestimates crowding (Johal and Battagel,
1997) and it is affected by the difference in lengths when
considering the arch as an arc (curve) however taking
measurements as a cord (straight line). Moreover, the
use of ruler introduces accumulative error.
• Segmental Approach: Divide arch into four segments
that can be measured as a straight line, e.g., 6-3, 3-1,
1-3, 3-6, to calculate space available. The arch can also
be divided into six segments with the canine as inde-
pendent segment to minimise the chord and arc differ-
ential effect. The required space can be calculated as the
total mesiodistal width of each individual tooth up to
the first molar on each side (Moorrees and Reed, 1954).
Problem of this method is underestimating the available
and hence tends to drive treatment plan towards extrac-
tions (Johal and Battagel, 1997).
• Brass wire/ Caliper Method: To measure the space
available with this technique, adapt a brass wire to the
line of occlusion, conforming close to the archform and
straighten it out in a line. To calculate space required,
measure the individual mesiodistal width of each tooth
and add them together (Nance, 1947). The weaknesses
of this technique is over-estimation of the available
space (Johal and Battagel, 1997).
• Microscopic reflex technique: This technique uses a
reflex microscope connected to a personal computer
installed with a customized program. To calculate space
available, the software simply subtracts from the total
tooth widths the mesiodistal overlaps of adjacent teeth,
including permanent first molars, making calculations
in millimeters. This technique have been previously
shown to be precise (Johal et al., 1995, Battagel, 1996),
however, the possible problems are expensive to use,
requires use of a specific computer program and the
maximum mesio-distal width is difficult to record if the
teeth are severely tipped.
Methods of size estimation for unerupted teeth (Mixed
Dentition Space Analysis)
Space analysis in mixed dentition requires estimation of
the size of unerupted teeth. This can be done in one of four
ways:
1. Study model and prediction table method
Moyer found a correlation between lower incisors and un-
erupted canine and premolars in a sample of North Ameri-

can Caucasian children (Moyers, 1973). It uses mesio-distal
widths of lower incisors to estimate canine size from propor-
tionality tables. Lower incisors were considered in prefer-
ence to upper incisors due to large variability in the size of
maxillary lateral incisors. This technique has a tendency to
overestimate the size of the unerupted teeth.
2. Study model based method
Tanaka and Johnston 1974 assess the size of unerupted teeth
based on study model measurements only. Once memo-
rized, this technique requires no radiographs or tables. The
steps include:
• Measuring the mesiodistal widths of lower incisors
(MD) in mm and divide it in half (MD/2),
• To calculate the total width of mandibular canine
and premolars in one quadrant, add 10.5 mm to the
above value (MD/2+10.5)
• To calculate the total width of maxillary canine and
premolars in one quadrant, add 11 mm to the above
value (MD/2+11)
3. Combination of Radiographs and Prediction Table
method (Staley and Kerber, 1980)
According to Staley and Kerber in 1980, the size of ca-
nines is difficult to predict from radiographs. Therefore,
this method uses mesiodistal measurements of incisors
from models, and widths of premolars from radiographs
to estimate size of unerupted canines.
A graph showing linear correlation was used to estimate
the size of mandibular canine. Although the graph was
accurate, it only predicted the size of lower canine and
required radiographs.
4. Magnification power technique
This technique is easy to be performed as it requires an
undistorted periapical radiograph and study models.
Radiographic enlargement must be taken into consider-
ation.
TwUP represents the true width of unerupted premolar,
TwSM represents the true width of an erupted decidu-
ous 1st molar on study model, RwEM represents the ra-
diographic width of an erupted deciduous 1st molar and
RwUP represents the radiographic width of unerupted
premolar. To assess the TwUP the following calculation
is applied: (TwSM /RwEM) X RwUP.
This approach can be applied to all ethnic groups and
used for both maxillary and mandibular teeth. Accuracy
depends on the quality of radiographic image which is
poor for canines. Magnification errors make the use of
photocopies of casts in computer programs unreliable
(Champagne, 1992)
Symmetry of the Arch
An asymmetric arch can still be present even if the face is
symmetric. This can be visualized on physical or virtual
casts by applying a transparent ruled grid over the upper
cast and coinciding it with midpalatal raphe.
Any distortions would be readily obvious. Some clinicians
prefer to orient the diagonal line connecting mesiolingual
and distobuccal cusp of maxillary 1st molar to the cusp tips
of upper canine bilaterally to confirm symmetry of arch.
Tooth Size Analysis or Bolton analysis
Teeth must be of proportional size for good occlusion
(PROFFIT et al., 2012), similar to the principle of the box
(mandible) and lid (maxilla). For example, in a denture set-
up, if large upper teeth are made to interdigitate with small
lower teeth, ideal occlusion will not be possible and one of
two scenarios would represent the final outcome: either ideal
molar relationship with increased overjet or normal overjet
with mesial occlusion of lower molars. This is called teeth
size discrepancy (TSD).
Maxillary lateral incisors and premolars show most predis-
position to variation in size.
Bolton analysis
With reference from a standard table, it compares combined
maxillary teeth’ mesiodistal widths to mandibular teeth, and
compares total widths of all maxillary and mandibular teeth,
except for 2nd and 3rd molars (Bolton, 1958).
Derived formula
Overall ratio= sum of mandibular 12 x100
sum of maxillary 12
Overall Bolton index (OBI) = 91.3% ± 1.91
Anterior ratio= sum of mandibular 6 x100
sum of maxillary 6
Anterior Bolton index (ABI) = 77.2% ± 1.65
These ratios can be a diagnostic tool for improved aesthetics
and function, without using a diagnostic setup. For normal
buccal segment size, the upper to lower buccal segment ratio
must be 1/1. Proffit suggested that a quick visual analysis of
anterior tooth size discrepancy can be checked by compar-
ing the size of upper laterals with lower lateral incisors and
concluded that the upper laterals must be of larger size. A
quick posterior tooth size discrepancy can be analysed from
a comparison of upper and lower 2nd premolars which must
be of equal size (Proffit, 2000).
When the ratio is greater than average mean it is either
maxillary deficiency or mandibular excess, or a combination
of both.
The disadvantage of Bolton analysis is that it applies only to

48
white females who made up most of his sample. TSD can be
corrected through build-ups of upper laterals, tipping small
upper laterals to take up more space, perform IPR in lower
arch or accept compromised molar relationship with de-
creased overjet. Since it is time-consuming to use reference
tables, computer-aided programs for digitizing or scanning
study casts are available, with the advantage that they are
quicker (Ho and Freer, 1999, Tomassetti et al., 2001).
A study by Othman and Harradine (Othman and Harradine,
2007) showed that:
• Repeated measurements for tooth size discrep-
ancy are recommended as there is high degree of
non-reproducibility,
• Computerized methods of assessment are
superior in sensitivity to visual methods,
• 17.4% of the sample had anterior tooth width
ratios and 5.4% had total arch ratios greater than 2
standard deviations from the average mean.
Expressing tooth size discrepancy in mm is prefer-
able to standard deviation approach. Therefore, a
requirement of tooth size correction of 2mm is an
appropriate threshold for clinical significance.
Average widths of permanent teeth (mm)
Maxillary 8.5 6.5 7.5 7.0 7.0 10.5 9.5 8.5
1 2 3 4 5 6 7 8
Man-
dibular
5.0 5.5 7.0 7.0 7.0 10.5 9.5 8.5
Bolton ratios, malocclusion and gender
Different authors have compared Bolton ratios in differ-
ent malocclusions; maxillary tooth size excess tendency
was present in Class II malocclusions and a tendency for
mandibular tooth excess in Class III (Nie and Lin, 1999).
Another study also found a significant mandibular excess in
Class III patients and an overall decreased Bolton ratio in
Class II cases (Araujo and Souki, 2003). From these find-
ings, it can be speculated whether these discrepancies have
a role in establishing the associated incisor relationship with
a malocclusion or if the skeletal discrepancy in a jaw and
its compensatory increase in tooth size results from growth
controlled mechanisms
Bolton ratios and ethnic groups
Many studies have investigated a relationship between
ethnic groups and Bolton ratios. A study demonstrated a
small but significant difference between Hispanic, black and
white groups (Smith et al., 2000). A significant difference
was found between gender groups, suggesting that the entire
Bolton sample was made up of white females. On the other
hand, some study showed that different malocclusions or
either genders do not present any significant difference in
TSD (Crosby and Alexander, 1989).
Bolton ratios and extractions
Extraction of first premolars has a significant impact on TSD
whereas 2nd premolar extraction has little effect (Saatçi and
Yukay, 1997).
Bolton ratios and Diagnostic Set-up (DS)
• DS is used for planning of tooth movements and to
exhibit effects of extraction e.g. when teeth are missing,
in severe TSD or when a single lower incisor extraction
is planned.
• Teeth are removed from planned extraction site on
study models and relocated to final tooth positions to
demonstrate final positions. The teeth are held in their
new positions with wax.
• DS can be performed digitally.
• DS is beneficial in that it aids patient understing
Exam Night Review
Clinical application of space analysis
• Diagnosis,
• Treatment planning,
• Planning of anchorage,
• Planning the mechanics,
• Analysis of space requirements,
• Informed consent.
Arch perimeter: Mesial contact of the 6 to the mesial con-
tact of the contralateral 6
Arch width intermolar: Mesiobuccal cusp tip of the 6 to
the mesiobuccal cusp tip point of the contralateral 6
Arch width intercanine: Canine cusp tip to canine cusp tip
Arch Depth: The distance from a line perpendicular to the
mesial surface of the permanent first molars to the midpoint
of central incisors at its greatest depth.
Arch expansion: Widening of the dental arch.
Arch lengthening: Increase of arch length by posterior
distalization or anterior proclination of incisors.
Permanent Dentition Space Analysis
RLSA consists of two main domains: space requirement and
space provision.
Assessment of Space Requirement

• Crowding or spacing,
• Curve of Spee leveling
• Arch expansion
• Anteroposterior position of incisor
• Tooth angulation
• Tooth inclination.
Utilisation or creation of space
Generally, space can be created by different way, remember
SPEED TRIAL:
• Stripping of teeth (interproximal reduction or slander-
ization)
• Proclination of teeth
• Extraction
• Expansion
• Distalisation of molar
• Torque changing
• Rotation and de-rotation
• Incremental/ differential growth (positive for advanc-
ing Class II, and negative for advancing class III with a
deterioration in arch relationship expected)
• Angulation changing
• Leeway space
Space can be utilised via:
• Tooth enlargement or build-ups
• Space opening for prostheses
• Mesial change in molar
Other Methods for Space Analysis in Permanent Denti-
tion
• Eye balling
• Visual Method
• Segmental Approach
• Brass wire/ Caliper Method
• Microscopic Reflex Technique
Methods of size estimation for unerupted teeth (Mixed
Dentition Space Analysis)
• Study model and prediction table method: It uses
mesio-distal widths of lower incisors to estimate canine
size from proportionality tables.
• Study model based method: Measuring the mesiodistal
widths of lower incisors (MD) in mm and divide it in
half (MD/2). To calculate the total width of mandible
3,4,5 add 10.5 mm to the above value (MD/2+10.5). To
calculate the total width of maxillary 3,4,5, add 11 mm
to the above value (MD/2+11)
• Combination of Radiographs and Prediction Table
method (Staley and Kerber, 1980): According to Staley
and Kerber in 1980, the size of canines is difficult to
predict from radiographs. Therefore, this method uses
mesiodistal measurements of incisors from models, and
widths of premolars from radiographs to estimate size
of unerupted canines.
• Magnification power technique
Bolton analysis
Overall ratio= sum of mandibular 12 x100
sum of maxillary 12
Overall Bolton index (OBI) = 91.3% ± 1.91
Anterior ratio= sum of mandibular 6 x100
sum of maxillary 6
Anterior Bolton index (ABI) = 77.2% ± 1.65
(Othman and Harradine, 2007) showed that:
• Repeated measurements recommended
• Computerized methods of assessment are superior in
sensitivity to visual methods
• 17.4% of the sample had anterior tooth width ratios and
5.4% had total arch ratios greater than 2 standard devia-
tions from the average mean
• Expressing tooth size discrepancy in mm is preferable.
Requirement of tooth size correction of 2mm threshold
for clinical significance

50
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5
1. Uses of orthodontic indices
2. Ideal characteristics of an index
3. Types of indices
4. Angle’s classification
5. Incisor classification
6. Index of Orthodontic Treatment Need (IOTN)
7. An Index of Orthognathic Functional Treatment
Need (IOFTN)
8. Peer Assessment Rating (PAR)
9. Index Of Complexity Outcome & Need (ICON)
10. American Board of Orthodontics Discrepancy
Index (ABO DI)
11. Handicapping Malocclusion Assessment Record
12. Little irregularity (LI) index
13. Crowding index
14. Maxillary expansion indices
15. Treatment difﬁculty index for unerupted maxil-
lary canines
16. Plaque index
17. Gingival index (GI)
18. Basic Periodontal Examination (BPE)
19. Helkimo Clinical Dysfunction (HCD) Index
20. GOSLON index
21. Tooth Wear Index
22. Root resorption indices
23. Maxillary suture fusion index
In this Chapter
Orthodontic Indices
Written by: Mohammed Almuzian, Haris Khan, Ayesha Tariq, Hajira Arham

Orthodontic Indices
52
An orthodontic index can be defined as a means of objec-
tively assessing occlusal status directly or indirectly. Indices
aim to determine one or more of the below features:
• Complexity: Defined as intricate or complicated.
• Difficulty: Defined as need of effort and skill.
• Severity: Defined as how far a malocclusion deviates
from normal.
Uses of orthodontic indices
Indices in orthodontics have many applications, these in-
clude:
1. Epidemiology applications such as:
• Determining the prevalence and incidence of oc-
clusal anomalies.
• Economic health care resource planning (financial
and workforce planning).
• For academic research.
2. Clinical assessment such as:
• Classification of malocclusion (e.g. Angle’s classifi-
cation, incisor classification).
• Diagnostic indices (e.g. Occlusal index).
• Treatment need or prioritisation (e.g. IOTN).
• Treatment complexity and difficulty assessment (e.g.
ICON).
• Treatment outcome and success assessment (e.g.
PAR).
3. Communication purposes with patients regarding their
malocclusion and for professional communication with col-
leagues.
Ideal characteristics of an index
These include:
• Reliable
• Reproducible
• Valid
• Cost-effective
• Universally acceptable
• Requires minimal adjustment
• Simple to administer
Types of indices
There are different types of orthodontic indices depending
on their applications and purposes, these include:
1. Indices used for classification of the malocclusion such
as:
• Skeletal classification
• Soft tissue classification
• Occlusal classification such as Angle’s, incisor and
canine classifications.
1. Indices used for diagnostic purposes such as:
• Occlusal index
• Handicapping Malocclusion Assessment Record
2. Indices used for assessment of treatment needs, com-
plexity and outcome such as:
• Index of orthodontic treatment needs (IOTN)
• Little’s irregularity index
• Peer Assessment Rating (PAR)
• ICON
3. Indices used for assessment of cleft lip/ palate treat-
ment outcomes such as:
• GOSLON Yardstick
• 5-year Old’s Index
• Bergalnd index for secondary alveolar bone graft-
ing (SABG)
• Kindealan index for SABG
4. Oral health indices such as:
• Plaque Index
• Community periodontal index for treatment needs
(CPITN)
• Gingival Index
Angle’s classification
Angle’s classification assesses the anterior-posterior relation-
ship regarding the first permanent molars. Angle described
three classes in 1899:
• Class 1 (neutrocclusion): The mesiobuccal cusp of
the upper first permanent molar occludes with the buc-
cal groove of the lower first permanent molar.
• Class 2 (distocclusion / post-normal): When the
mesiobuccal cusp of the upper first permanent molar
occludes mesial to the buccal groove of the lower first
permanent molar.
• Class 3 (mesiocclusion/ Pre-normal): when the
mesiobuccal cusp of the upper first permanent molar
occludes distal to the buccal groove of the lower first

Orthodontic Indices 53
permanent molar
Modification to Angle’s classification
Includes Class 2 subdivision (Class 2 molar on one side
and class 1 molar on the other side) and Class 3 subdivision
(Class 3 molar on one side and class 1 molar on the other
side). Angle’s classification is a simple, widely accepted,
reliable and reproducible method of occlusal classification.
However, it cannot be used in primary dentition, the dental
or skeletal original of aetiology cannot be distinguished, it
can only assess discrepancies in the sagittal direction. More-
over, this method depends on the first permanent molars
being fixed points in the jaw structure, which is not valid, as
environmental factors can affect their position.
Full unit Class 2 and Class 3 malocclusion
One unit is defined as the mesial-distal width of a premolar
and represents the distance from the mesiobuccal cusp tip
to the distobuccal cusp tip of the first permanent molar. Full
unit Class 2 means that the mesiobuccal cusp of the upper
molar is one unit mesial to the buccal groove of the lower
molar, i.e., the upper molar’s mesiobuccal cusp occludes in
the embrasure space of the lower second premolar and lower
first permanent molar. While, full unit class 3 means that
the mesiobuccal cusp of the upper molar is one unit distal to
the buccal groove of the lower molar, i.e., the upper molar’s
mesiobuccal cusp occludes in the embrasure space of the
lower first permanent molar and second molar. Fractions of
the unit are also used, commonly ¼, ½ , ¾ unit Class 2 and
Class 3
Incisor classification
The incisor classification was developed by the British
Standards Institutes in 1983. It is based on the lower incisor
edges and the upper central incisor cingulum plateau. These
include:
• Class 1: The lower incisor edges occlude with or lie
immediately below the cingulum plateau of the upper
incisors.
• Class 2: The lower incisor edges occlude or lie
posterior to the cingulum plateau of the upper incisors.
Two divisions of this class were described:
1. Division 1: The upper incisors are pro-
clined or normal inclination, with an increased
overjet.
2. Division 2: The upper central incisors are
retroclined (lateral incisors may be retroclined
or proclined). The overjet is usually decreased
but may be increased.
• Class 3: The lower incisor edges occlude or lie
anterior to the cingulum plateau of the upper incisors.
Overjet is usually reduced or reversed.
• Modification to the incisor classification includes
Class 2 indefinite which means that one upper cen-
tral incisor is retroclined, and the other is proclined
(Gravely and Johnson, 1974) and Class 2 intermediate
which refers to a clinical situation where the upper inci-
sors are upright or slightly retroclined, and the overjet is
5-7 mm (Williams and Stephens, 1992).
Skeletal classification
Skeletal classification is obtained through clinical assessment
and supported with cephalometric analysis. Three skeletal
categories are described using ANB angle:
• Class 1: Lower dental base is related to the upper
dental base (ANB= 2-4˚).
• Class 2: Lower dental base is retruded relative to the
upper dental base (ANB> 4˚).
• Class 3: Lower dental base is protruded relative to
the upper dental base (ANB <2˚).
Wits appraisal and Ballard conversion can be used similarly
to ANB.
Index of Orthodontic Treatment Need (IOTN)
IOTN was developed by Brook (Brook and Shaw, 1989),
who developed a specific ruler to aid assessment. IOTN
has two components: Dental health component (DHC) and
Aesthetic component (AC).
With regards to the Dental Health Component (DHC),
Brook and Shaw showed the reproducibility of the DHC is
very good (86.4%), and agreement was moderate for intra
and inter-examiner agreement (0.84-0.71). They also found
that the common trait causing disagreement in descending
order of frequency are: crowding, increased overjet, cross-
bites and overbites (Brook and Shaw, 1989).
With regards to the Aesthetic Component (AC), a high
level of agreement was found between patients, parents and
orthodontists when grading the patient’s AC (0.75-0.89)
(Evans and Shaw, 1987). This was supported by a separate
study which showed the correlation coefficient was reason-
ably high (Brook and Shaw, 1989).
Dental health component (DHC)
This was developed based on the index treatment priority
used by the Swedish Dental Board. It attempts to rank mal-
occlusion, and it is used as a clinical tool to assess eligibility
for NHS treatment. The DHC consists of 14 qualifiers and
5 grades (Figures 1 and 2). Only the highest-scoring trait
needs to be recorded, as this determines the patient’s grad-
ing. Grades 1 and 2 represent no need for orthodontic treat-
ment, grade 3 refers to the borderline need for treatment

Orthodontic Indices
54
while grades 4 and 5 indicate the definite need for treatment.
a overjet h hypodontia
b reverse overjet with no masticatory or speech
problems
i posterior lingual crossbite
c crossbite m reverse overjet with masticatory or speech problems
d deisplacemnet of contact points p defects of cleft lip and palate
e open bite s submerged deciduous teeth
f deep bite t partially erupted teeth, tipped and impacted against adjacent
teeth
g good occlusion x presence of supernumerary teeth
Table 1: Abbreviations used in IOTN
Scoring the DHC
Scoring the DHC is performed in order as follows MOCDO
which stands for: M - Missing teeth, O – Overjet, C – Cross-
bites, D - Displacements and O – Overbite.
1. Missing teeth (5i, 5h or 4h) relates to impacted/ impeded
eruption and hypodontia.
• Impeded eruption (5i) is a score for a tooth that is
not accommodated in the arch due to a lack of space
or obstruction. The tooth is considered impeded if
the space remaining is less than or equal to 4mm,
and the angulation is not favourable in the horizon-
tal direction. In the mixed dentition, if the distance
from the mesial contact point of the first permanent
molar to the distal contact point of the lateral incisor
is less than 18 mm or 17 mm in the upper and lower
dental arches, respectively, the unerupted canine is
considered impacted.
• Hypodontia (5.h or 4.h): The IOTN classification
of hypodontia is only used if the space requires
orthodontic treatment, i.e., space opening or space
closure. If there is no requirement for orthodontic
treatment, i.e., accept space or primary tooth in situ,
this does not meet the IOTN classification due to no
orthodontic treatment being required. 5h means
extensive hypodontia with more than one tooth
missing in a quadrant, requiring pre-restorative or-
thodontics. 4h means less extensive hypodontia, one
tooth missing in a quadrant, requiring orthodontic
space closure or pre-restorative orthodontics.
2. Overjet is measured using the ruler held parallel to the
occlusal plane and radial to the line of the arch (2a, 3a, 4a,
5a) (Table 2). The overjet is recorded to the labial aspect of
the incisal edge of the most prominent incisor (lateral or
central incisors). The lower grade is allocated if the incisor
falls on the IOTN ruler line. Reverse overjet applies when
all four incisors are in lingual occlusion/crossbite (2b, 3b,
4b, 4m,5m) (Figure 3). If the reverse overjet is greater than 1
mm, it is essential to investigate whether the individual has
masticatory or speech (M&S) difficulties and classify
accordingly. There are several methods of investigation, but
a simple approach is to ask the individual to count from 60-
70, noting any difficulty in pronunciation. In addition, any
signs and symptoms of mandibular dysfunction should be
checked.
Positive Overjet Reveres Overjet
2. a compe-
tent lips
3.5mm -
6mm
2. b 0mm - 1mm
3. a incom-
petent lips
3.5mm -
6mm
3. b 1mm -
3.5mm
4. a 6mm -
9mm
4. m M&S prob-
lems
4. b No M&S
problem
1mm -
3.5mm
greater than
3.5mm
5. a greater
than
9mm
5.m M&S prob-
lem
greater than
3.5mm
Table 2: Positive and negative overjet in IOTN
3. Crossbite: When 1, 2 or 3 (but not all) incisors are in lin-
gual occlusion/crossbite, the relationship is classified as ante-
rior crossbite (2.c, 3.c, 4.c, 4.l) (Table 3). Posterior crossbite
means that the posterior tooth or teeth are in full crossbite
in a buccal or lingual perspective or cusp to cusp and might
be associated with a displacement. The grade recorded
depends on the severity of discrepancy between retruded
contact position (RCP) and intercuspal position (ICP). The
greater the discrepancy between RCP an ICP, the higher the
grade. Scissor bite means that the entire buccal segment in
lingual occlusion.
Grade and Qualifier Discrepemcy between IP and RCP
2.c 1<=1mm
3.c 1 - 2mm
4.c >2mm
Table 3: Crossbite in IOTN

Grade 5
(very great)
Increased overjet > 9mm
Extensive hypodontia with restorative implicatoins (more than one tooth missing in any quadrant) requir-
ing pre-restorative orthodontics
Impeded eruption of teeth (with the exception of the third molars) due to corwding, displacements, the
presence of supernumeray teeth, retained deciduoud teeth and any pathological cause
Reverse overjet greater than 3.5mm with reported masticatory and speech difficulities
Defects of cleft lip and palate
Submerged deciduous teeth
Grade 4
(great)
Increased overjet > 6mm but 9mm
Reverse overjet > 3.5mm with no masticatory or speech deifficulties
Anterior or posterior crossbite with > 2mm discrepency between returded contact position and intercuspal
position
Servere displacemetns of teeth > 4mm
Extreme lateral or anterior openbite > 4mm
Increased and complete overbite with labial or palatal trauma
Less Extensive hypodontia (one tooth missing per quadrant) requiring prerestorative othodontics or orth-
odontic space closure to obviate the need for a prosthesis
posterior lingual cross bite with no functional
occlusal contact in one or more buccal segments
Reverse overjet greater than 1mm but 3,5 mm with recorded masticatory and speech difficulties
Partially erupted teeth, tipped and imapcted against adjacent teeth
Supplemental teeth
Grade 3
(moderate)
Increased overjet > 3.5 mm but 6mm with incompetent lips
Reverse overjet greater than 1mm but 3.5mm
Anterior or posterior cross bite with > 1mm but 2mm discrepency between returded contact position and
intercuspal position
Displacement of teeth > 2mm but 4mm
Lateral or anterior open bite greater than 2mm but 4mm
Grade 2
(Little)
Increased overjet > 3.5 mm but 6mm with competent lips
Reverse overjet greater than 0mm but 1mm
Anterior or posterior cross bite with 1mm discrepency between returded contact position and intercuspal
position
Displacement of teeth > 1mm but 2mm
Anterior posterior openbite > 1mm but 2mm
Increased overbite 3.5mm without gingival contact
Prenormal or postnormal occlusions with no other anomalies. includes up to half a unit discrepency
Grade 1
(None)
EXtremely minor malocclusions including displacements < 1mm
Table 4: Dental health component (DHC) of IOTN

Orthodontic Indices
56
or poor colour matching in anterior restorations.
Within the UK NHS a patient with a DHC of 3 or more, and
an AC of 6 or more, qualify for state-funded NHS treatment.
Treatment priority and need according to the AC scale are:
• Grades 1-3: No/slight need for treatment.
• Grade 4: Mild need for treatment.
• Grades 5-7: Borderline need for treatment.
• Grades 8-10: Definite need for orthodontic treat-
ment.
Overbite Openbite
Grade
and
Qualifier
Grade
and
Qualifier
2. f Increased
greater than or
equal to 3.5mm
2.e Anterior or pos-
terior openbite
1mm - 2mm
3.f Deep overbite
complete on
labial or palatal
tissues but no
trauma
3.e Anterior or pos-
terior openbite
2.1mm - 4mm
4.f Increased
and complete
overbitewith
labial or palatal
trauma
4.e External lateral
openbites great-
er than 4mm
Table 6 : Overbite and openbite in IOTN
Index of Orthognathic Functional Treatment Need
(IOFTN)
IOFTN was developed in 2014. It prioritizes severe maloc-
clusions due to skeletal abnormalities, not amenable to
orthodontic treatment alone. It applies to patients who have
completed facial growth (Ireland et al., 2014) (Figure 9).
he advantages of IOFTN including being reliable and
straightforward to use (Howard-Bowles et al., 2017) and
both digital and plaster models can be used (McCrory et al.,
2018). However, the limitation of IOFTN are that this index
only relates to the functional need for treatment, it does not
include psychological and other clinical indicators for treat-
ment. Moreover, Class 3 malocclusion patients benefit more
from this index than patients with class 2 skeletal patterns
(Borzabadi-Farahani et al., 2016).
Advantages and disadvantages of the IOTN
Table 7 explain the advantages and disadvantages of the
4. Displacement of contact points (2.d, 3.d, 4.d) (Table
5) Contact point displacement represents the degree of
anatomical contact points deviation from the line of the
arch and only the worst displaced tooth is recorded, how-
ever, vertical displacements from the occlusal plane are not
recorded. Spacing is not also recorded unless the contact
point is displaced from the line of the arch. Contact points
displacement between deciduous and permanent, and that
due to teeth rotation (generally premolars) are not recorded.
Grade and Qualifier Displacement
2. d 1mm - 2mm
3. d 2.1mm - 4mm
4. d greater than 4mm
Table 5: Contact point displacement in IOTN
5. Overbite and openbite (2.e/f, 3.e/f, 4.e/f) (Table 6): Deep
bite and open bite apply to any of the four incisors. The larg-
est vertical discrepancy is recorded. It is important to record
gingival or palatal trauma as a result of a deep overbite.
Other criteria of the DHC
These include:
• Buccal occlusion (2g): The buccal occlusion is as
• sessed irrespective of whether the teeth interdigitate
in Angle’s Class 1, 2 or 3.
• Tipped teeth (4t): When a permanent tooth has
erupted and is tipped against an adjacent tooth.
• Submerging teeth (5.s): Submerged teeth are not re-
corded unless only two cusps remain visible and/or
the adjacent teeth are tipped towards the submerged
tooth.
• Supernumerary teeth (4.x): It is graded only if a su
pernumerary tooth requires extraction followed by
orthodontic alignment and/or space closure.
Aesthetic Component (AC)
AC was developed by Evans (Evans and Shaw, 1987) and it
was originally called the SCAN (Standardised Continuum
of Aesthetic Need) (Figure 7 and 8). The photographs were
originally arranged in order by a panel of lay persons. The
AC is a ranking system 1-10 using coloured photographs
which assess dental attractiveness. The number 1 is the most
attractive while number 10 is the least attractive (figure 7).
The grading is made by the clinician by best matching the
patient front occlusion to AC photographs but not specific
morphological similarities to the photo.
Monochromic photographs are used for dental cast assess-
ments. (Woolass and Shaw, 1987). It has been reported that
monochromic photographs have the advantage that asses-
sors are not influenced by oral hygiene, gingival condition,

IOTN.
Advantages Disadvantages
Valid Crowding represented a prob-
lem in recording when the pa-
tient is in the mixed dentition.
Reproducible The AC has no side view rating
or class III malocclusion
Acceptable to clinician Objective index
Easy and quick to apply No representation of aesthetic
or skeletal relationship
Can be used directly on
patients or on dental
casts
No assessment of crowding
which relies on displacement
only
Yield quantitative data
which can be analysed
Table 7: Advantages and disadvantages of the IOTN
A
Figure 7: Monochromic copy of AC scale.
Figure 8: Aesthetic component of the IOTN
Peer Assessment Rating (PAR)
This index was developed by Richmond and team (Rich-
mond et al., 1992). It was formulated over a series of six
meetings in 1987 with a group of 10 experienced orthodon-
tists. The index can record the malocclusion at any stage of
treatment where a score is assigned to various occlusal traits
of a malocclusion. The individual scores are summed to ob-
tain an overall total, representing the degree a case deviates
from ideal alignment and occlusion.
Study models are used for scoring along with a specifically
designed ruler that has all the information summarized
which makes measurement quick and easy to perform.
A total score of zero indicates good alignment and higher
scores (rarely beyond 50) indicate significant levels of ir-
regularity. The difference between the pretreatment and
posttreatment scores represent the degree of improvement as
a result of orthodontic intervention and active treatment.
There are 11 components of the PAR index:
1. Upper anterior segment.
2. Lower anterior segment.
3. Upper right segment.
4. Upper left segment.
5. Lower right segment.
6. Lower left segment.
7. Right buccal occlusion.
8. Left buccal occlusion.
9. Overjet.
10. Overbite.
11. Centreline
Anterior segments
Anterior segments with a weighting of 1, extends from the
mesial anatomical contact point of the canine to the mesial
anatomical contact point of the canine on the contralateral
side (Table 8). Displaced contact points are not recorded for
the first, second and third molars, this is because contact
points are broad and are extremely variable within the
normal range. Displaced contact points are recorded at the
shortest distance between contact points, parallel to the
occlusal plane. The occlusal features recorded are crowding,
spacing, and impacted teeth.
In the case of potential crowding in the mixed dentition,
average mesiodistal widths are used to calculate the space
deficiency. Impacted teeth are recorded when the space
available for the tooth is equal or less than 4 mm (Table 9).

Orthodontic Indices
58
5. Very great need of treatment
Defects of cleft lip and palate and other craniofacial anomalies
Increased overjet greater than 9mm
Reverse overjet >= 3mm
Open bite >= 4mm
Complete scissors bite affecting whole buccal segments with sign of functional disturbance and or occlusal trauma
Sleep apnoea not amenable to other treatments such as MAD or CPAP (as determined by sleep studies)
Skeletal anomalies with occlusal disturance as a result of trauma or pathology
4. Great need of treatment
Increased overjet >= 6mm and <=9mm
Reverse overjet >= 0mm and < 3mm with functianl difficulties
Openbite < 4mm with functioanl difficulties
Increased overbite with evidence of dental or soft tissue trauma
Upper labial segment gingival exposure 3>= at rest
Facial asymmertry assocaited with occlusal disturbance
3. Moderate need of treatment
Reverse overjet >= 0mm and <3mm with no functionl difficulties
Open bite < 4mm with no functional difficulties
Upper labial segment gingival exposure <3mm at rest, but with evidence of gingival/periodontal effects
Facial asymmetry with no occlusal disturbance
2. Mild need of treatment
Increased overbite but no evidence of dental or soft tisssue trauma
Upper labial segement gingival exposure < 3mm at rest with no evidence of gingival/periodontal effects
Facial asymmetry with no occlusal disturbance
1. No need of treatment
Speech Difficulties
Treatment purely for TMD
Occlusal features not classified above
Table 9: An Index of Orthognathic Functional TreatmentNeed (IOFTN)
Displaced contact points due to poor restoration, contact
points between deciduous teeth and orthodontic extraction
spaces are not recorded. Spacing in the anterior segment
resulting from extraction, agenesis or avulsion of incisors or
cuspids is recorded as follows:
• If the plan is to close space, then the space is record-
ed.
• If the plan is to open space and restore it, then the
space is not recorded unless it is less than or equal
to 4 mm.
PAR Score Amount of teeth displace-
ment
0 0 mm – 1mm
1 1.1 mm – 2mm
2 2.1 mm – 4mm
3 4.1 mm- 8mm
4 Greater than 8mm
5 Impacted teeth
Table 9: Anterior crowding

Table 10: Mixed dentition crowding assessment using
average mesio-distal width
Upper
Canine 8mm Total 22mm
Impaction < =
18mm
1st Premolar 7mm
2nd Premolar 7mm
Lower
Canine 7mm Total 21mm
Impaction < =
17mm
1st Premolar 7mm
2nd Premolar 7mm
Buccal occlusion
Buccal segments, with a weighting of 1, extends from the
mesial anatomical contact point of the last molar (whether
this was the first, second or third molar) to the distal ana-
tomical contact point of the canine in the same quadrant.
Recordings of both right and left sides in occlusion in three
dimensions (A-P, vertical and transverse) is performed
(Table 10). Temporary developmental stages and submerg-
ing deciduous teeth are excluded
Table 11: Buccal occlusion assessment
PAR Score Table 4: Buccal occlusion
discrepancy
Vertical
0 No discrepancy in intercuspa-
tion
1 Lateral open bite on at least 2
teeth greater than 2 mm
Antero-posterior
0 Good interdigitation (Cl 1, Cl
2 or Cl 3)
1 Less than ½ unit discrepancy
2 ½ a unit discrepancy (cusp to
cusp) or more
Transverse
0 No crossbites
1 Crossbite tendency
2 Single tooth in crossbite
3 More than 1 tooth in crossbite
4 More than 1 tooth in scissor
bite
Overjet
The most prominent aspect of any incisor (central or lateral)
is recorded with a ruler held parallel to the occlusal plane
(Table 12).
Overjets and crossbites are recorded collectively, therefore, if
there is a positive overjet and one of the incisors or canines
in crossbite, the scores should be added together. Overjet
has a weighting of 6.
Table 12: Overjet component measurements
Overjet Anterior crossbites
0 0-3 mm 0 No discrepancy
1 3.1- 5mm 1 One or more teeth
edge to edge
2 5.1- 7mm 2 One single tooth in
crossbite
3 7.1- 9mm 3 Two teeth in cross-
bite
4 Greater than
9mm
4 More than two
teeth in crossbite
Overbite
The vertical overlap (OB) or openbite (AOB) of the anterior
teeth is recorded (Table 13 & 14). The tooth with the greatest
overlap is recorded, if the OB and AOB are present, then they
should be added. Overbite has a weighting of 2.
Table 13: Overbite component measurements
Open bite
0 No openbite
1 Openbite less than and equal to
1mm
2 Openbite 1.1 mm – 2 mm
3 Openbite 2.1 mm- 3 mm
4 Openbite greater than or equal
4mm
Table 14: Deep bite component measurements
0 Less than or equal to 1/3
coverage of the lower incisor
1 Greater than 1/3, but less
than 2/3 coverage of the
lower incisor
2 Greater than 2/3 coverage of
the lower incisor
3 Greater than or equal to full
tooth coverage.
Centerlines
Centerline discrepancy is assessed in relation to the lower
central incisors (Table 15). If a lower incisor is missing, mea-
surement is not recorded. Centerlines has a weighting of 4.

Orthodontic Indices
60
Table 15: Centrelines component measurements
PAR Score Table 8: Centrelines discrepancy as-
sessment
0 Coincident and up to ¼ lower inci-
sor width
1 ¼ to ½ lower incisor width
2 Greater than ½ lower incisor width
Advantages of PAR index
These include:
• It has been reported that the PAR index has ex-
cellent reliability within intra and inter-examiner
agreement (0.93-0.87) (Richmond et al., 1992).
• Easy and quick with use of the PAR ruler.
• PAR can be used for all types of malocclusion and
treatment modalities.
• The score provides an estimate of how far a case de-
viates from normal.
• PAR is a good tool in measuring the perceived de-
gree of improvement and therefore the success of
treatment and clinical performance.
Disadvantages of PAR index
These include:
• It provides a single summary score for all the oc-
clusal anomalies, and is therefore not related to an
individual patient’s needs.
• The reliability of the upper buccal segments was
found to be low, this was due to the variation of up-
per posterior tooth size. Larger teeth have broader
contact points which result in inaccurate assessment
(Richmond et al., 1992).
• Hamdan and Rock suggested the PAR index over-
weights the overjet (weighting of 6), and under
weights the overbite (weighting of 2) (Hamdan and
Rock, 1999).
Outcome assessment of PAR
There are three methods of assessing outcome using the PAR
Index.
• PAR score change: Reduction from pre-treatment to
post-treatment PAR score. 22-point reduction indi-
cates great improvement.
• PAR percentage change: Percentage change from
pre-treatment to post-treatment. A percentage im-
provement greater than 70% can be considered a
good standard for orthodontic treatment. 30-70%
reduction represents an improved outcome. Less
than 30% reduction is considered to be of no im-
provement or worse outcome.
• Graphical assessment: Assessment using a graph
(nomogram).
Index Of Complexity Outcome & Need (ICON)
ICON index was purposed by Daniels (Daniels and Rich-
mond, 2000) as the first index based on international orth-
odontic opinion of 97 orthodontists. ICON index comprises
of an assessment of five traits, each trait is multiplied by a
weighting factor. The final score is the sum of all the five trait
scores. ICON scoring and interpretations are provided in
Table 16 & 10.
he traits which make up the ABO DI are presented in Table
10 and include:
• Overjet and anterior crossbite.
• Overbite and anterior open bite and lateral open-
bite.
• Crowding.
• Buccal occlusion.
• Lingual posterior crossbite and buccal posterior
crossbite.
• Cephalometric analysis: Consisting of ANB angle,
SN-Go-Gn and lower incisor to Go-Gn angle.
• An additional category designated ‘other’ is pre-
served for conditions that may affect or add to the
complexity of treatment.
Need and acceptability Threshold values
Pretreatment need >43 Treatment need
End treatment acceptability < 31 Acceptable
Complexity grade (Pretreatment) Score range
Easy < 29
Mild 29 to 50
Moderate 5 1 to 63
Difficult 64 to 77
Very difficult > 77
Improvement Grade
(Pretreatment score – 4x Post-
treatment score)
Score Range
Greatly improved > -1
Substantially improved -25 to - l
Moderately improved -53 to -26
Minimal improved -85 to -54
Not improved or worse < -85
Table 16: Interpretation of ICON scores

American Board of Orthodontics Discrepancy Index
(ABO DI)
Overjet
Overjet is scored as the distance between the incisal edge of
the most forward positioned upper incisor and the most for-
ward positioned mandibular incisor:
• Overjet of 0 mm (edge to edge): 1 point.
• Overjet of 0 to 3 mm: 0 point.
• Overjet of 3.1 - 5 mm: 2 points.
• Overjet over 9 mm: 5 points.
If there is a negative overjet (anterior crossbite), the score is
recorded as 1 point per mm. per anterior tooth in crossbite.
Overbite
Positive overbite is scored as follow:
• Overbite of up to 3 mm: 0 point are scored.
• Overbite between 3.1 to 5 mm: 2 points are scored.
• Overbite between 5.1 to 7 mm: 3 points are scored.
If the lower incisors are impinging on the palatal tissue (100%
overbite), then 5 points are scored.
Anterior openbite is scored as follow:
• If the upper and lower incisors are in an edge to edge
relationship (overbite = 0): 1 point is scored.
Traits Weighting
factor
Score 0 1 2 3 4 5
Aesthetic 7 1-10 as
judged us-
ing IOTN
AC
Upper
arch
Crowding 5 Only the
highest
trait either
spacing or
crowding
Less than
2mm
2.1- 5mm 5.1- 9mm 9.1-13mm 13.1-
17mm
More than
17mm or
impacted
teeth
Spacing 5 Up to
2mm
2.1-5mm 5.1- 9mm More than
9mm
Crossbite 5 Transverse
relation-
ship of
cusp to
cusp or
worse
No cross-
bites
Cross bite
present
Anterior Open bite 4 Only the
highest
trait either
openbite
or overbite
Complete
bite
Less than
1mm
1.1-2mm 2.1-4mm More than
4mm
Deep bite 4 Lower
incisor
coverage
Up to 1/3
tooth
1/3- 2/3
coverage
2/3 up to
full cov-
ered
Fully
covered
Buccal
segment
anterio-
posterior
relation-
ship
3 Left and
right
added
together
Cusp to
embrasure
relation-
ship only,
C1, C2,
C3
Any cusp
relation up
to but not
including
cusp to
cusp
Cusp to
cusp rela-
tionship
Table 17: Scoring of ICON scores

Orthodontic Indices
62
Table 18: ABO DISCREPANCY INDEX
Discrepency Index
Overjet 0mm
(edge to edge) 1pt
1mm - 3mm 0 pts Occlusion
3.1 - 5mm 2 pts Class I end on 0 pt
5.1 - 7mm 3 pts End on Class II or III 2 pts perside
7.1 - 9mm 4 pts Full Class II or III 4 pts per side
>9mm 5 pts Beyond Class II or III 1 pt per mm additional
Negative OJ(x-bite) 1 pt. per mm per tooth= Total _____________
Total _______________ Lingual Posterior X Bite
Overbite 1 pt per tooth Total
0 - 3mm 0 pt Buccal Posterior X Bite
3.1 - 5 mm 2 pts 2 pts per tooth Total _______
5.1- 7mm 3 pts Cephalometrics
Impinging 100% 5 pts ANB > 5.5 or < -1.5 4pts
Total _______________ Each additional degree 1 pt
Anterior Openbite SN -GO -GN 27 degree - 37 degree 0 pt
0mm (edge to edge)= 1pt SN -GO -GN > 37 degree 2 pts per degree
then 2 pts per mm per tooth SN -GO -GN < 27 degree 1 pt per degree
Total _____________ IMPA >98 degree 1 pt. per degree
Crowding Total____________
0 - 3mm 1 pt OTHER 2 pts
3.1 - 5mm 2 pts
5.1 - 7mm 7 pts INDICATE PROBLEMS
>7mm 7 pts _________________
_____________
Total ______________
• For each millimeter of openbite, 2 points are scored
for each upper tooth involved from canine to canine.
• No points are scored for the upper canines if they
are buccally displaced out of the arch.
In terms of the lateral openbite, for each upper tooth (from
the first premolar to third molar) in an openbite relationship
with the lower arch, 2 points are scored per mm of openbite
for each tooth.
Crowding
When scoring crowding the most crowded dental arch is con-
sidered. The scoring include:
• 1 to 3 mm:1 point is scored.
• 3.1 - 5 mm 2 points are scored.
• 5.1 - 7 mm 4 points are scored.
• Greater than 7 mm: 7 points are scored.
Buccal Occlusion
When scoring occlusion, the Angle molar classification is
used as below:
• If the mesiobuccal cusp of the upper first molar oc-
cludes with the buccal groove of the mandibular first
molar no points are scored (this includes 1/4 unit
class 2 or 3).
• If the occlusal relationship is 1/2 unit class 2 or 3
(cusp to cusp), then 2 points are scored per side.
• If the relationship is a full class 2 or 3, then 4 points
are scored per side.
• If the relationship is greater or beyond a full unit
class 2 or 3, then 1 additional point is scored per mm
for each side.

Posterior crossbite
In lingual posterior crossbite, for each upper posterior tooth
in lingual crossbite (from the first premolar to the third mo-
lar), 1 point is scored. In buccal posterior crossbite, for each
upper posterior tooth (from the first premolar to the third
molar) in complete buccal crossbite, 2 points are scored.
Cephalometric analysis
If ANB angle is greater than 5.5˚ or less than -1.5˚, 4 points
are scored. For each additional degree above or below these
values, an additional point is scored. If the SN-Go-Gn angle
is between 27 ˚ to 37˚, Zero points are scored, greater than
37˚, 2 points are scored. For each additional degree above
37˚, 1 point is scored and for each additional degree below
27˚, 1 point is scored. If the Go-Gn angle is greater than 98˚,
1 point is scored for each additional degree above 98 ˚.
Other variables
At the discretion of the examiner, an additional 2 points may
be awarded for each of the following conditions:
• Missing teeth (except for third molars).
• Supernumerary teeth.
• Impactions (except for third molars).
• Ectopic eruption.
• Anomalies of tooth size and shape.
• Dental midline discrepancies greater than 3 mm.
• Skeletal asymmetries (involving dental compensa-
tion for case completion).
Advantages of ABO DI
• Detailed/comprehensive.
• Measures case complexity. Case complexity however
is a subjective outcome. The information can be used
to aide decisions of who should treatment the pa-
tient. The ABO DI is used for case assessment for
board registration in America.
Disadvantages of ABO DI
These include:
• Complicated to perform and time consuming.
• Time-consuming.
• Relies on cephalograms and therefore irradiation for
indexing.
• Reproducibility is lower than other indices.
Handicapping malocclusion assessment record
The purpose of the HMAR is to establish a priority index for
treatment of dentofacial deformity. The HMAR factors haz-
ards to oral health from the deformity, as well as the psycho-
social effects of dentofacial aesthetics, mandibular function
and speech (Salzmann, 1968). The HMAR consists of:
1. Intra-arch deviations including:
• Missing teeth.
• Crowding.
• Rotations.
• Spacing.
2. Inter-arch relationships including:
• Overjet.
• Crossbite.
• Overbite.
• Openbite.
• Molar and canine relationships.
Little irregularity (LI) index
LI was developed by Little (Little, 1975). It assesses the ir-
regularity of the lower labial segment by measuring the linear
displacement of the contact points in mm (from the mesial
contact point of the canine to the mesial contact point of the
canine on the contralateral side). The sum of the 5 displaced
contact points represents the relative degree of anterior ir-
regularity (Table 11). It is used in the assessment of stability
and relapse. >3.5mm of irregularity is deemed unacceptable.
The advantages of LI index are being easy to use and it pro-
vides the extent of post treatment relapse of incisor crowding.
However, the disadvantages of LI index are that the index is
outdated method. If two teeth are crowded and rotated, but
maintain contact point proximity, LI does not register the
crowding.
Crowding index
In occlusal view, crowding is determined by measuring the
available horizontal space, parallel to the occlusal plane, be-
tween the least displaced interproximal contact points. The
actual width of the corresponding tooth was then deducted
from the available space to give a resultant amount of crowd-
ing (positive measure) or spacing (negative measure) for each
tooth.
Table 19: Irregularity Index
Irregularity Score
Perfect alignment 0mm
Minimal irregularity 1-3mm
Moderate irregularity 4-6mm
Severe irregularity 7-9mm
Very severe irregularity 10mm

Orthodontic Indices
64
Maxillary expansion indices
It has been stated that there is a constant relationship between
the sum of the maxillary incisor widths (SI=Sum of Incisors
width) and the width of the maxillary arch width in an ideal
uncrowded dentition. This method overestimated average
maxillary widths.
The formula was then transposed to allow arch width pre-
diction: Required inter-premolar width = SI/ 0.80 Required
inter-molar width = SI/0.6.
McNamara proposed a simple rule of thumb indicating an
ideal average intermolar width in males is 37 mm and in fe-
males is 36 mm. However, this proposal overestimates the
average width. Schwarz built his analysis based on the face
type and SI. It is considered as an accurate method for maxil-
lary arch width analysis. As per Schwarz, in a narrow face, the
inter- first premolar width is equal to SI + 6 mm while the
intermolar width is equal to SI + 12 mm. the inter- first pre-
molar width is equal to SI + 7 mm while the intermolar width
is equal to SI + 14 mm. While in broad faces, the inter- first
premolar width is equal to SI + 8 mm while the intermolar
width is equal to SI + 16 mm.
Treatment difﬁculty index for unerupted maxillary ca-
nines
The prognosis for alignment of an impacted maxillary canine
is affected by several factors which have been listed in order
of greatest difficulty (McSherry, 1996) (Pitt et al., 2006):
• Horizontal position.
• Age of patient.
• Vertical height.
• Bucco-palatal position.
• Angulation to midline.
• Rotation.
• Coincidence of arch midlines.
• Alignment and spacing of the upper labial segment.
• Condition of primary canine.
• Missing teeth.
Plaque index
The plaque index was developed by Silness and Loe (Silness
and Loe, 1964). This index is used to easily and reliably record
the levels of supragingival plaque. However, plaque index
does not indicate plaque control nor record subgingival area.
It is subjective scoring in which the plaque is scored as:
• 0= No plaque at gingival margin.
• 1= Initial deposit of plaque at gingival margin (not
visible to the eye).
• 2= Plaque at the gingival margin (visible to the eye).
• 3= Heavy plaque accumulation on tooth.
It is recommended to score the buccal and lingual surfaces of
the sextants of the arch (2 surfaces per index tooth). If an in-
dex tooth is missing, score the nearest tooth in that sextant. If
no teeth are present, record the sextant as X. If plaque thick-
ness varies along the gingival margin, score according to the
worst situation. The overall score is the sum of the buccal and
lingual surfaces of the 6 teeth (12 surfaces).
Calculation of plaque index
• Plaque index for a surface of a tooth range from 0-3.
• Plaque index for an individual tooth: Buccal and lin-
gual scores are added and divided by two.
• Plaque index for a group of teeth: Scores for individ-
ual teeth are added and then divided by the number
of teeth examined.
• Plaque index for the individual: Score for each of the
teeth are added and then divided by the total num-
ber of teeth examined.
• Plaque index for a group of people: All indices are
taken and divided by the number of individuals.
• Interpretation of plaque scoring is given in Table 12.
Table 20: Interpretation of Plaque index
Rating scores
0 Excellent
0.1-0.9 Good
1.0-1.9 Fair
2.0-3.0 Poor
Gingival index (GI)
GI assesses of prevalence and severity of gingivitis. It is rec-
ommended to score the four surfaces of tooth no. 16, 12, 24,
36, 32 and 44.GI scores are:
• 0= Healthy.
• 1= Mild inflammation, slight change in color.
• 2= Moderate inflammation, redness, moderate glaz-
ing, bleeding on pressure.
• 3= Severe inflammation, redness, hyperplasia, ten-
dency for spontaneous bleeding.
Basic Periodontal Examination (BPE)
BPE was developed from the Community Periodontal Index
of Treatment Needs (CPITN) (Cutress et al., 1987). BPE
should be undertaken on all patients undergoing orthodon-

tic treatment. The BPE divides the dentition into 6 sextants:
• Upper right 17 to 14.
• Upper anterior 13 to 23.
• Upper left 24 to 27.
• Lower right 47 to 44.
• Lower anterior 43 to 33.
• Lower left 34 to 37.
The highest score is recorded in each sextant using WHO
621 probe. The probe has a ‘ball end’ 0.5 mm in diameter,
and a black band from 3.5 to 5.5 mm. Light probing force
should be used (20-25 grams). Examination is recorded as
follow:
• Code 0 - No pockets over 3mm, no calculus and
overhangs and no bleeding on gentle probing.
• Code 1 - No pockets over 3mm, no calculus/over-
hangs but bleeding on gentle probing.
• Code 2 - No pockets over 3mm but calculus /
plaque retentive factors and bleeding on gentle
probing would be present.
• Code 3 – Pocket up to 3.5-5.5mm present (black
band of probe partially visible, indicating pocket of
4-5 mm).
• Code 4 – Pocket >5.5 mm (black band entirely
within the pocket, indicating pocket of 6 mm or
more)
• * indicates furcation involvement.
Helkimo Clinical Dysfunction (HCD) Index
This epidemiological index was introduced by Van Der
Weele (van der Weele and Dibbets, 1987). It measures sever-
ity of TMJ dysfunction, however, it gives same weight to
all symptoms regardless whether it is muscular to articular
disorders. Other drawback associated with this index is
that the scale of 0, 1, 5 is not continuous, the index does not
indicate the severity between score numbers, hence is it not
a valid nor reproducible tool. The criteria for this index are
provided in Table 22.
GOSLON index
The GOSLON (Great Ormond Street, London and Oslo)
index was introduced by Mars et al.(Mars et al., 1987) as a
clinical tool to allow categorization of the dental relation-
ships (Antero-posterior, vertical and transverse relationship)
in 10 years old patients with unilateral cleft lip/ palate. It is
valuable in predicting treatment need (orthodontic treat-
ment, surgical treatment).
GOSLON index has five discrete categories. The GOSLON
index is treatment-linked (e.g. anterior crossbite with retro-
clination of the incisors can be corrected more easily than
anterior crossbite with normal incisor inclination) and is
therefore more useful than a specific anomaly-score alone.
Advantages and disadvantages of GOSLON index are listed
in Table 19.
Table 21: Advantages and disadvantages of GOSLON
yardstick
Advantages Disadvantages
1.It can differentiate be-
tween arch relationships
and interference of facial
morphology
1.The judges should be
trained in the use of this
index and recalibration is
necessary to assure consis-
tency
2. Good inter and intra-
examiner reliability
2. It only scores ULCP
3. It shows clinical aspects
in 3 planes of study.
3. Its validity has not been
investigated
4. Differentiates between
the degree of malocclusion
during all stages of dental
development
4. It is difficult since it
requires a cluster of adults
with UCLP who have been
treated by primary surgery
only
5. It can predict surgical
outcomes at an early age of
5 years
5. It is less powerful than an
objective constant numeri-
cal measurement scale
Tooth Wear Index
Smith and Knight introduced the tooth wear index which
assesses tooth wear on all four visible surfaces (Smith and
Knight, 1984). It assesses pathological tooth wear (Table
16). All teeth present are scored irrespective of the aetiology
of tooth wear. The tooth wear index measures multifacto-
rial tooth wear and distinguishes between acceptable and
pathological levels of wear. However, it takes a lot of time to
measure the full dentition and it is also a research tool and
cannot be used without computer assistance.
Root resorption indices
Root resorption classification score was originally proposed
by Malmgren (Malmgren et al., 1982) and consists of four
grades:
• Grade 1: Irregularity in the apical root contour,
maintaining the original root length.
• Grade 2: Resorption of up to 2mm of the root length.
• Grade 3: Resorption from 2mm up to 1/3 of the root
length.
• Grade 4: Severe root resorption above 1/3 of the root
length.
•

Orthodontic Indices
66
Table 22: Criteria for Helkimo Clinical Dysfunction Index
Symptom Criteria Score
Impaired range of movement Normal range of movement 0
Slightly impaired mobility 1
Severe impaired mobility 5
Smooth Movement without joint sounds and deviation < 2mm 0
Impaired TMJ Function Joint sounds in one or both joints and deviation > 2mm on opening or closing 1
Locking or luxation of joint 5
Muscle Pain No tenderness to palpation 0
Tenderness to palpation in 1-3 sites 1
Tenderness to palpation in 4 or more sites 5
TMJ pain No tenderness to palpation 0
Tenderness to palpation in 1-3 sites 1
Tenderness to palpation in 4 or more sites 5
Pain on movement of mandible Pain on 1 movement 0
Pain on 2 or more movements 1
No pain on movements 5
This index was modified and expanded by Alamadi and
team into (Alamadi et al., 2017)
• Grade 1: Irregular root contour.
• Grade 2: less than 1/4 of the root is resorbed.
• Grade 3: 1/4 of the root is resorbed.
• Grade 6: Middle resorption (apex of the tooth is
maintained).
Another index for root resorption is the Sharpe’s index
(Sharpe et al., 1987) which also classified root resorption
into 4 categories
• Grade 1: No apical root resorption.
• Grade 2: Slight blunting of the root apex.
• Grade 3: Moderate blunting of the root apex up to ¼
of the root length.
• Grade 4: Excessive blunting of the root apex beyond
the ¼ of the root length.
Levander and colleagues (Levander et al., 1998) develop
another 4 categoriesbased index for root resorption
• Grade 2: Root resorption apically, less than 2mm
(Minor).
• Grade 3: Root resorption apically, from 2mm to 1/3
of the root’s length (severe).
• Grade 4: Root resorption exceeding 1/3 of the root’s
original length.
Table 23: Tooth Wear Index
Score Surface Criteria
0 B/L/O/I/C No loss of enamel surface
characteristics.
No loss of contour.
1 B/L/O/I/C Loss of enamel surface
characteristics.
Minimal loss of contour.
2 B/L/O/I/C Loss of enamel leading
to dentine exposure for
less than one third of the
surface.
Defect less than 1 mm deep.
3 B/L/O/I/C Loss of enamel leading
to dentine exposure for
less than one third of the
surface. Loss of enamel and
substantial loss of dentine
Defect between 1-2 mm
deep.
4 B/L/O/I/C Complete enamel loss with
pulp exposure or secondary
dentine exposure.
Defect more than 2mm
deep.
B: Buccal; L: Lingual; O: Occlusal; I: Incisal; C: Cervical.

EXAM NIGHT REVIEW
ORTHODONTIC INDICES
An orthodontic index or malocclusion index can be defined
as a means of objectively assessing occlusal status.
Uses of orthodontic indices
• Epidemiology
• Clinical assessment
• Communication
General characteristics of an index
• Reliable.
• Reproducible: Same classification with repeated
evaluations.
• Valid: The index should measure what it was intend-
ed to measure.
• Universally acceptable to profession and public.
• Requires minimal adjustment.
• Simple to administer.
• Cheap.
Types of indices
• Classification indices.
• Diagnostic indices
• Treatment assessment (need, complexity and out-
come)
• Cleft outcomes
• Oral health indices
Index of Orthodontic Treatment Need (IOTN)
• IOTN was developed by Brook (Brook and Shaw,
1989).
• A specific ruler had been developed aid assessment.
• IOTN has two components:
1. Dental health component (DHC).
2. Aesthetic component (AC).
Dental health component (DHC)
• This was developed based on the index treatment
priority used by the Swedish Dental Board.
• It attempts to rank malocclusion and is used as a
clinical tool to assess eligibility for NHS treatment.
• The DHC consists of 14 qualifiers and 5 grades.
• Grade 1 represents little or no need for treatment,
and grade 5 represents the great need for treatment.
Maxillary suture fusion index
Several methods for assessment of maturation of mid-palatal
suture are available including chronological age, dental de-
velopmental age, CVM staging, five stage mid-palatal suture
maturation method and hand/ wrist radiograph.
Mid-palatal suture density ratio (MSDR) by Gruntheid
(Grünheid et al., 2017)
MSDR by Gruntheid is a CBCT based technique that uses
GRAY levels substitute for measuring bone density levels of
the palatal regions. Ratio value 0 refers to less calcification
of sutures while ratio value 1 refers to more calcified sutures.
In comparison to other methods MSDR shows a greater cor
relation with the actual measurement of skeletal expansion.
Five stage midpalatal suture maturation method (accord-
ing to CBCT)
It was proposed by Angelieri (Angelieri et al., 2013). Stage 1
to 3 can benefit from conventional RME, but stages 4 and 5
require surgically assisted RME (Table 21).
Stage 1 Straight high-density sutural line at
midline, little or no interdigitation
Stage 2 Scalloped appearance of high-den-
sity sutural line at midline
Stage 3 Parallel, scalloped high density
lines close to each other (separated
in some areas by small low-density
spaces)
Stage 4 Fusion completed in palatine bone,
no evidence of a suture
Stage 5 Fusion completed anteriorly (max-
illary region)
Table 24: Five stage midpalatal suture maturation method
(according to CBCT)

Orthodontic Indices
68
(Ireland et al., 2014).
Peer Assessment Rating (PAR)
• This index was developed by Richmond et
al.(Richmond et al., 1992)
• A total score of zero indicates good alignment, and
higher scores (rarely beyond 50) indicate significant
levels of irregularity.
• The difference between the pretreatment and post-
treatment scores represent the degree of improve-
ment.
• There are 11 components of the PAR index:
1) 1. Upper anterior segment.
2) 2. Lower anterior segment.
3) 3. Upper right segment.
4) 4. Upper left segment.
5) 5. Lower right segment.
6) 6. Lower left segment.
7) 7. Right buccal occlusion.
8) 8. Left buccal occlusion.
9) 9. Overjet.
10) 10. Overbite.
11) 11. Centrelines.
Outcome assessment of PAR
• PAR score change: Reduction from pre-treatment
to post-treatment PAR score. 22-point reduction indicates
great improvement.
• PAR percentage change: Percentage change from
pre-treatment to post-treatment. A percentage im-
provement more significant than 70% can be con-
sidered a good standard for orthodontic treatment.
30-70% reduction represents an improved outcome.
Less than 30% reduction is regarded as no improve-
ment or worse outcome.
• Graphical assessment: Assessment using a graph
(nomogram).
Index Of Complexity Outcome & Need (ICON)
• ICON was the first index based on international
orthodontic opinion and was proposed by Daniels
(Daniels and Richmond, 2000).
• The index was based on the opinion of 97 interna-
tional orthodontists.
• This index is comprised of an assessment of five
traits.
Ruler is used for measurement.
• Various abbreviations used in IOTN are given in fig-
ure 1.
• The scoring of dental health components is given in
figure 2.
• Only the highest-scoring trait needs to be recorded,
as this determines the grading for the patient.
• Treatment priority and need according to DHC
• Grades 1 and 2 represent no need for orthodontic
treatment
• Grade 3 refers to the borderline need for treatment
• Grades 4 and 5 indicate definite need for treatment
• It assesses few points in order as follows (MOCDO):
1) 1. M - Missing teeth (5i, 5.h, 4.h)
2) 2. O - Overjet (5.a, 4.a, 3.a, 2.a / 5.m, 4.m, 4.b,
3.b, 2.b)
3) 3. C - Crossbites (4.c, 3.c, 2.c)
4) 4. D - Displacements (4.d, 3.d, 2.d)
5) 5. O - Overbite (4.f, 3.f, 2.f / 4e, 3.e, 2.e)
Aesthetic Component (AC)
• The AC is a ranking system 1-10 using coloured
photographs which assess dental attractiveness. The
number 1 is the most attractive, while number 10 is
the least attractive.
• The grading is made by the orthodontist matching
the patient to AC photographs but not specific mor-
phological similarities to the photo.
• In the UK, a patient with a DHC of 3 or more, and
an AC of 6 or more, qualify for state-funded NHS
treatment.
• Treatment priority and need according to the AC
scale:
• Grades 123: No/little need for treatment.
• Grade 4: Mild need for treatment.
• Grades 5-7: Borderline need for treatment.
• Grades 8-10: Definite need for orthodontic treat-
ment.
An Index of Orthognathic Functional Treatment Need
(IOFTN)
• IOFTN was developed in 2014 and prioritised se-
vere malocclusions due to skeletal abnormalities,
not amenable to orthodontic treatment alone. It ap-
plies to patients who have completed facial growth

• Each trait is multiplied by a weighting factor.
• The final score is the sum of all the five trait scores.
American Board of Orthodontics Discrepancy Index
(ABO DI)
The traits which make up the ABO DI are:
• Overjet and anterior crossbite.
• Overbite and anterior open bite and lateral openbite.
• Crowding.
• Buccal occlusion.
• Lingual posterior crossbite and buccal posterior
crossbite.
• Cephalometric analysis: Consisting of ANB angle,
SN-Go-Gn and lower incisor to Go-Gn angle.
• An additional category designated ‘other’ is pre-
served for conditions that may affect or add to the
complexity of treatment.
Basic Periodontal Examination (BPE)
Code 0 - No pockets over 3mm, no calculus and overhangs
and no bleeding on gentle probing.
Code 1 - No pockets over 3mm, no calculus/overhangs but
bleeding on gentle probing.
Code 2 - No pockets over 3mm but calculus / plaque reten-
tive factors and bleeding on gentle probing would be pres-
ent.
Code 3 – Pocket up to 3.5-5.5mm present (black probe band
partially visible, indicating pocket of 4-5 mm).
Code 4 – Pocket >5.5 mm (black band entirely within the
pocket, indicating pocket of 6 mm or more)
* - Furcation involvement.
Root resorption indices
Malmgren’s root resorption index (Malmgren et al., 1982)
• Grade 1: Irregularity in the apical root contour,
maintaining the original root length.
• Grade 2: Resorption of up to 2mm of the root length.
• Grade 3: Resorption from 2mm to 1/3 of the root
length.
• Grade 4: Severe root resorption above 1/3 of the root
length.
Root resorption index according to Levander (Levander et
al., 1998)
• Grade 2: Root resorption apically, less than 2mm
(Minor).
• Grade 3: Root resorption apically, from 2mm to 1/3
of the root’s length (severe).
• Grade 4: Root resorption exceeding 1/3 of the root’s
original length.

Orthodontic Indices
70
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187-90.

6
1. Intra-oral sources of OA
2. Extra-oral sources of OA
3. Terms and principles used with OA
4. Classification of OA
5. Supplementing the OA unit
6. Measuring OA loss
7. OA in three planes
8. Assessment of OA need
In this Chapter
Orthodontic
Anchorage
Written by: Mohammed Almuzian, Haris Khan, Farhana Umer

Orthodontic Anchorage
72
Orthodontic Anchorage (OA) is the resistance to un-
wanted reactionary forces during the orthodontic treatment
(Proffit et al., 2018). OA should always be planned in 3 planes
of space: anterior-posterior, lateral and vertical (Naish et al.,
2015).
Intra-oral sources of OA
These include:
• Cortical alveolar bone
• Soft tissue
• Teeth
• Occlusal interferences (Dudic et al., 2013), i.e. occlu-
sal interference with the anchor segment increases
its anchorage value.
• Basal bone
• Labial musculature (OA is derived from the action
of muscles such as a lip bumper)
Extra-oral sources of OA
These include:
• Cranium
• Forehead
• Neck
• Chin
Terms and principles used with OA.
OA loss is the undesired movement of the anchor units
during orthodontic treatment. OA burn (planned loss) is
performed when occlusal objectives are achieved, and the
aim is to close residual spaces. Each tooth’s root surface
area (RSA) is proportional to its anchorage value. Greater
resistance has been provided with increased RSA (Hixon et
al., 1970). However, the relationship between RSA and tooth
movement is not linear. Therefore, other factors are involved
in (Pilon et al., 1996). The rate of tooth movement (RTM)
is related to force per unit RSA “differential force theory”
(Baumrind et al., 1984). Large individual variation exists in
the RTM for a particular force applied (Dudic et al., 2013).
Maximum RTM could be achieved with forces ranging from
104-454gm (Ren et al., 2004). RTM increases with increased
applied force, but only up to a point (Quinn and Yoshikawa,
1985).
Classification of OA
OA relates to all three planes of space and can be gained
from intra-oral and extra-oral sources.
A. According to the amount of movement of the anchor unit
(Nanda and Burstone, 1993) including:
• Group A or maximum anchorage in which the ante-
rior teeth/ Unit retraction (active unit) moves 75%
into the extraction site. In comparison, 25% of the
remaining space is utilised by the protraction of the
posterior teeth (anchor unit). Thus, the expectation
in this type of anchorage is predominantly the re-
traction of the anterior teeth.
• Group B or moderate anchorage includes 50% of re-
traction of anterior teeth into the extraction site and
50% protraction of posterior teeth. Therefore, there
is equal movement from both the active and anchor
units.
• Group C or non-critical anchorage in which the
anterior retraction utilises 25% of the created space,
while protraction of posterior teeth occupies 75%.
Thus, a more significant movement of the anchor
unit is seen in this case.
• Absolute Anchorage where the posterior teeth pro-
tract minimally (less than 1mm). Hence, posterior
teeth position is essentially maintained.
B. According to the number of teeth/type of movement in-
cluding:
• Simple OA refers to one tooth providing anchorage
to another tooth.
• Compound OA refers to a group of teeth providing
anchorage to one tooth or a smaller number of teeth.
• Reciprocal OA refers to an equal force applied to
teeth of similar anchorage value (RSA) that causes
equal movement towards/away from each other, for
example, symmetrical arch expansion or closing a
midline diastema.
• Stationary OA is achieved by allowing the active unit
to tip against bodily resistance of the reactive (an-
chor unit)
• Differential OA represents staged tooth movement
to reduce anchorage demand/taxing, such as tipping
the active unit first then uprighting it. The Differen-
tial force theory involves a combination of station-
ary and differential OA.
C. According to the source and the involved jaws, including:
• Intraoral orthodontic anchorage such as intramaxillary
and intermaxillary OA. An example of intermaxillary
OA is Class II myofunctional appliances that utilise the
oral muscle’s force. Another example is the intermaxillary
elastics which relies on the opposite arch to provide OA.
However, prolonged use can lead to excessive extrusion,
canting the occlusal plane, and tipping the anterior teeth.
• Extraoral orthodontic anchorage includes head-
gear (HG) or a protraction facemask (PFM).

Orthodontic Anchorage 73
• Soft tissue borne OA which is obtained from:
1. Palatal vault: OA can be obtained through contact-
ing the palate and using this interaction to resist
tooth movement, e.g. upper removable appliance or
Nance appliance.
2. Lip Bumper: The muscular forces of the displaced
lower lip are transferred to the molars through lip
pads and heavy wire attached to the molars; this re-
sults in molar anchorage reinforcement, uprighting
and distalisation.
• Bone borne OA which is obtained from:
1. Palatal arch, Nance, Lingual arch (Rebellato et al.,
1997) generate OA by relying on the cortical an-
chorage theory. Cortical anchorage theory is based
on the principle that the cortical bone resorbs slow-
er than medullary bone; therefore, a slower rate of
movement occurs when the roots of posterior teeth
contact cortical bone while moving buccally, hence,
increasing OA value. However, in a clinical study, the
palatal arch was found to have a minimal increase in
OA benefit (Zablocki et al., 2008). An RCT found
no clinical significance between a palatal arch and
Nance appliance in terms of OA loss though patients
prefer a palatal arch over a Nance appliance (Stivaros
et al., 2010). The use of ankylosed teeth is another
example of cortical anchorage theory (Kokich et al.,
1985)
2. Bone supported/engaged devices such as implants
/ miniscrews / TADs / plates can provide a direct
anchorage (Ismail and Johal, 2002). The orthodon-
tic force could be applied directly from the TAD to
one or multiple teeth or indirectly where TAD is
used to anchor one or multiple teeth in a unit; an
orthodontic force is then used against this anchor
unit to orthodontically move a segment. An RCT
found no clinically or statistically significant differ-
ences in the effectiveness of 3 methods of anchorage
supplementation (TADs, Nance and HG). Hence,
patient preferences should be considered (Sandler
et al., 2014). A systematic review and meta-analysis
showed moderate-quality evidence favouring mini-
screw performance compared with conventional an-
chorage devices (Alharbi et al., 2018).
Supplementing the OA unit
These include:
1. Treatmentplanningrelatedfactors:Forexample,aplanthat
includesutilisingprostheticimplants,ifpossible,ormodifying
theextractionpattern.Extractionofteethclosetotheactiveunit
is associated with less OA demand, i.e. first premolar extrac-
tioninsteadofsecondpremolarextraction(Naishetal.,2015).
2. Bracket Type / Prescription: Standard edgewise appliances
preserve around 0.8mm of OA compared with straight wire
appliances (SWA) in the maxillary arch; this may be due to
SWA achieving greater torque and straining anchorage units
than SEA (Lotzof et al., 1996). TipEdge appliances that uti-
lise the differential force theory preserve more OA (0.6mm)
than SWA, though this is not a clinically significant (Usmani
et al., 2002). Theoretically, MBT brackets are associated with
minimal OA due to reduced tip compared with the Roth sys-
tem. Moreover, the increased molar buccal root torque in the
MBT prescription reinforces anchorage via the cortical bone
theory. On the other hand, some propose that lower torque
in the Roth prescription preserves OA compared with MBT.
3. Biomechanical factors: The use of low force magnitude
and archwire bends such as toe-in (1st order) and tip-back
(2nd order) bends could help preserve OA. Stopped archwire
such as crimpable stops mesial to the first molar and utility
arches can be used to prevent mesial movement of the molar.
However, this approach can be at the expense of the proclina-
tion of incisors. They are pushing mechanics that preserves
OA compared with pulling mechanics at the cost of procli-
nation of the anterior segment. Theoretically, Laceback pre-
serves OA by maintaining the arch length. However, it was
concluded that there are no differences in overall OA loss,
anterioposterior and vertical changes of the lower incisors
secondary to the use of Laceback (Irvine et al., 2004). Lace-
backs are effective in maxillary canine retraction with sig-
nificantly less mesial molar movement (Fleming et al., 2013).
4. Stagged tooth movement while correcting centre lines
by moving one active tooth at a time might minimise me-
sial movement of the molar. Two-stage retraction includes
retraction of canines followed by retraction of the incisors. A
systematic review confirmed that both one-stage (en-masse)
and two-stage retraction are equally effective in space clo-
sure with minimal difference in AO (Sueri and Turk, 2006).
Measuring OA loss
OA loss is assessed by comparison of tooth position relative
to a stable structure over time using one of the following
methods:
1. Cephalometric analysis such as:
a) Subjective (visual) cephalometric structural analy-
sis using maxillary and mandibular Bjork’s stable structures
b) Objective cephalometric analysis using different
analyses such as:
• Lower incisor position about N-Pog or NB or MP:
• Pitchfork analysis in which the reference structures
are the maxilla and zygoma. This analysis mea-
sures AP movement of the upper and lower incisors
and molars. However, there is no measurement of

74
changes in incisor inclination or canine angulation
(Rizk et al., 2018).
• Pancherz technique measures the linear changes
from a perpendicular drawn from Sella to the occlu-
sal line. However, this method depends on maxillary
structures and the occlusal plane, which are subject
to change.
2. The intraoral photograph is mainly a subjective visual
technique.
3. Study model measurement by superimposing 3D models
on the palatal rugae. This method is becoming widely used
with developments in the digital imaging (Johnston, 1996).
The palatal rugae are a reliable structure for superimposition
with a margin of error of +0.8mm (SD). Therefore, changes
less than 1.6mm are unlikely to be statistically significant
(Sandler et al., 2014).
4. Direct clinical assessment by assessing the changes in oc-
clusal relationships, especially if one arch remains untreated
as a baseline.
OA in three planes
Orthodontic forces are applied in vertical, transverse, and
sagittal (AP) planes. Therefore, OA requirements must be
considered in 3 dimensions.
1. Vertical Orthodontic Anchorage: Consideration of ver-
tical OA is essential in treating anterior open bite and deep
bite. In anterior deep bite, flattening the COS involves recip-
rocal OA through the extrusion of the posterior teeth and
intrusion of anterior teeth. The second permanent molar
should be bonded/banded to increase anterior intrusion.
This is thought to increase the vertical OA value of the an-
chorage unit. Therefore, more significant intrusion occurs
in the anterior segment. In an anterior open bite, adding
a compensatory COS in the upper arch intrudes the pos-
terior teeth when combined with anterior intermaxillary
“box” elastics. This approach is referred to as ‘Kim mechan-
ics’. Anterior elastics withstands the intrusive effects of the
compensatory curve of Spee imparted by the wire and can
be considered a type of intermaxillary compound anchorage.
2. Transverse Orthodontic Anchorage: For bilateral expan-
sion, there are usually an equal number of teeth on both sides,
which achieves reciprocal OA. To accomplish a unilateral
expansion, the anchorage side (correct side) should have a
greater number of teeth (compound anchorage), or the ex-
pander is placed closer to the active unit, the side on which
expansion is required. This results in greater force on the
active side and a lower force on the anchorage unit. While
aligning the palatally placed ectopic canines, an OA demand-
ing in 3 planes of space and mainly in the transverse plane is
required. This can be obtained by stabilising the arch with a
heavy stainless steel archwire or a palatal arch.
3. Anteroposterior Orthodontic Anchorage (AP): Anchor-
age in the AP plane is reinforced with various appliances, e.g.
Nance appliance, palatal arch, headgear, upper removable ap-
pliance, or miniscrews.
Assessment of OA need
Several factors conjointly play a role in determining the OA
requirement, including:
1. General factors include age, medical condition, individu-
al variation and patient compliance.
2. Treatment plan factors such as:
• Treatment aims and the amount of anterior teeth re-
traction compared to posterior protraction.
• Type of movement required as the anchorage de-
mand is high for bodily movement compared to tip-
ping movements (Hoggan and Sadowsky, 2001).
• Extraction pattern as the anchorage demand is pro-
portional to the position of the extracted tooth.
3. An intra-arch relationship such as:
a) The involved arch, as the maxillary arch, is mainly are
more prone to OA loss than the mandibular arch; this is
likely due to a combination of factors:
• Maxillary anterior teeth are larger than mandibular
anterior teeth, therefore, having greater root surface
area and anchorage demand when they are moved
(Zhu, 2017). Also, the surface area of the roots of
maxillary posterior teeth (in the buccolingual direc-
tion not overall) is less than the mandibular poste-
rior teeth.
• Maxillary posterior teeth are usually upright/tipped
mesially. Hence, they are more susceptible to OA
loss (Alexandros, 2014). Also, the maxillary occlu-
sal plane is usually inclined clockwise with a higher
anterior force vector than the lower occlusal plane.
• The mandibular bone is denser than the maxillary
bone (upper posterior is less dense than the upper
anterior, lower alveolar bone is the denser bone)
(Geron, 2003, Devlin, 1998).
• Most prescriptions have high tip and torque built in
the upper anterior brackets compared to lower ante-
rior brackets; this is associated with high anchorage
demand.
• Individual variations (Alikhania, 2018).
• Combination of the above.
b) The amount of crowding as severe crowding requires
more OA due to multiple tooth movements.
c) The location of crowding, the greater the distance be-

tween the anchor unit and the displaced active unit/teeth,
the greater the OA demand.
d) Teeth angulation, for instance, distally angulated teeth,
have a higher OA demand to align and retract than upright
or mesially inclined teeth due to greater root movement be-
ing required.
e) For instance, the incisors’ inclination, retroclined upper
incisor in Class II Division 2 cases, requires greater OA to
torque the upper incisors.
4. The inter-arch relationship such as:
• The degree of overbite and overjet: Increased over-
bite and overjet require greater OA.
• The amount of centerline discrepancy
• The severity of skeletal relationship in the antero-
posterior and vertical direction: It has been proven
that high angle cases have higher OA demands. This
is mainly because the bone in high angle cases is less
dense than the bone in low angle cases, favouring
tooth movement and OA loss. Moreover, the orien-
tation of the occlusal plane in high angle cases fa-
vour the mesial movement of the anchor teeth. A
study showed that the weak muscle fibres of high
angle cases lead to low occlusal interlocking force
than low-angle cases, facilitating OA loss (Naish et
al., 2015).
• Buccal relationship affects occlusal interlocking; for
instance, cases with full unit molar relationships
have robust cusps to fossae interlocking relationship,
which could act as a point of resistance to OA loss
compared to the incomplete unit cases (e.g. ½ unit
Class II or Class III).
5. Biological factors related to the anchorage units include
the root surface area of the anchor units. For example, lower
incisors require less anchorage than canines and premolars
due to reduced surface area. Tooth clinical conditions and
periodontal support affect OA support; for instance, peri-
odontally compromised teeth or short-rooted teeth provide
low OA support.
EXAM NIGHT REVIEW
Anchorage is the resistance to unwanted reactionary forces
during treatment in all three planes of space (Profit, 2000).
Intra-oral sources of anchorage
• Cortical alveolar bone.
• Soft tissue.
• Teeth.
• Basal bone.
• Labial musculature in which the OA is derived from
the action of muscles via a vestibular shield or lip
bumper.
Extra-oral sources of anchorage
• Occipital.
• Forehead.
• Neck.
• Chin
Classification of OA
A. Based on the movement of the anchor unit.
B. According to the manner of the force application.
C. According to the source and the involved jaws.
• Intra-oral OA.
• Extra-oral OA.
Supplementing OA unit
Treatment planning steps to reinforce anchorage
• The utilisation of dental implants if possible.
• Extraction pattern: Extraction of the teeth close to
the active unit will reduce the OA demand.
Appliance prescription
• Straight-wire appliance (SWA).
• Tip-Edge appliance.
• MBT brackets.
Biomechanical options
• The use of toe-in (1st order) and tip-back (2nd or-
der) bends.
• The use of light forces on the active unit
• Laceback: RCT → No benefit in controlling both sag-
ittal and vertical position of lower. incisors (Alharbi
et al., 2018).
• Stopped arches (Crimpable hooks mesial to the first
molar) and utility arches.

76
• Pushing mechanics.
• Correcting centerlines → one tooth at a time.
• Subdivision of the desired movement: A systematic
review confirmed that both one step (en-masse re-
traction) and two-step methods are effective for
space closure, but the one-step method with TADs
is better in anchorage reinforcement and amount of
retraction (Sueri and Turk, 2006).
Assessment of anchorage need
Several factors conjointly play a role in determining the OA
needs, including:
A. General factors
• Age.
• Medical condition.
• Medication.
• Individual variation.
• Patient compliance.
B. Treatment plan factors
• Treatment Aims.
• Type of movement required (Rizk et al., 2018).
• Extraction pattern.
C. Treatment mechanics factors
• Appliance prescription: MBT has less anchorage de-
mand
• Appliance type: Tip-Edge appliance has a reduced
anchorage demand
• Upper removable appliance lower anchorage de-
mand than a fixed appliance.
D. Intra-arch relationship
• Involved arch: Maxillary arch susceptible to OA loss.
• Amount of crowding.
• Location of crowding.
• Tooth angulation.
• The inclination of the incisors
E. Inter-arch relationship
• Overbite.
• Overjet.
• Centerline discrepancy.
• A-P Skeletal relationship.
• Vertical Skeletal relationship.
• Occlusal interlocking.
F. Factors related to the anchorage units:
• Root surface area of the anchor units.
• Tooth condition and periodontal support.
Evidence Summary
• An RCT found no significant clinical difference be-
tween a palatal arch (Goshgarian) and a Nance ap-
pliance in preventing mesial drift or distal tipping.
However, palatal arches are associated with reduced
patient discomfort (Stivaros et al., 2010).
• An RCT found no clinical or statistically signifi-
cant differences in the effectiveness of 3 methods of
anchorage supplementation (TADs, Nance palatal
arches and HG). Hence patients preferences should
be considered (Sandler et al., 2014).
• An RCT found that the use of laceback ligatures
in first premolar extraction cases doesn’t benefit
in controlling both sagittal and vertical position of
lower incisors(Irvine et al., 2004).
• An RCT found that lacebacks do not prevent ULS
proclination or molar position. The amount of ULS
proclination depends on the angulation of the ca-
nine, and the laceback makes no difference (Usmani
et al., 2002).
• According to a systematic review and meta-analysis,
no evidence was found that Lacebacks effectively
control the sagittal position of incisors during the
alignment phase (Fleming et al., 2013).
• A systematic review confirmed that both one-step
and two-step retraction methods are effective for
space closure. Still, the one-step method with TAD
anchorage is better in anchorage reinforcement and
the retraction (Rizk et al., 2018).

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7
1. A brief history of TADs
2. Design features of TADs
3. Characteristics for ideal TADs
4. Osseointegrating screws
5. Types of osseointegrating screws
6. Mechanically retained screws
7. Design features of miniscrews
8. Indications of TADs
9. Contraindications and limitations of TADs
10. Advantages of TADs
11. Disadvantages of TADs
12. Stability and failure of TADs
13. Factors affecting failure of TADs
14. The failure rate of TADs according to the site of
insertion
15. Special features in the TADs
16. How to optimise the success rate of TADs?
17. Post-operative instructions
18. Direct versus indirect anchorage
19. Bicortical anchorage
20. Complications associated with TADs
In this Chapter
TEMPORARY ANCHORAGE
DEVICES
Written by: Mohammed Almuzian, Haris Khan, Ahmed M. A. Mohamed, Zahid Majeed

Temporary Anchorage Devices
80
Atemporary anchorage device (TAD) is temporarily fixed
to the bone to enhance orthodontic anchorage. TADs are also
known as temporary intraoral skeletal anchorage devices
(TISADs), ortho implants, mini-implant, microimplant (MI),
miniscrew, microscrew (MS) or orthodontic pins (Cope, J.B.
2005). TADs provide anchorage either by supporting the
teeth of the reactive unit (indirect anchorage) or by obviating
the need for the reactive unit altogether (indirect anchorage)
(Alharbi, F., Almuzian, M., et al. 2018).
TADs differ from conventional dental implants, which sup-
port a prosthesis. Although traditional dental implants may
be used for orthodontic anchorage, they are not considered
as temporary anchorage devices as they are not removed after
the orthodontic treatment (Singh, K., Kumar, D., et al. 2010).
A brief history of TADs
Osseointegrating titanium implants were first described in
1969 (Branemark, P.I., Adell, R., et al. 1969). Vitalium im-
plants used to correct increased overbites were reported in
1983 (Creekmore, T.D. and Eklund, M.K. 1983). In 1997 first
titanium miniscrews was described by Kanomi (Kanomi, R.
1997), and in 1999, the first mini-plate were used for orth-
odontic purposes (Umemori, M., Sugawara, J., et al. 1999).
Design features of TADs
These include:
• Based on the materials used (Singh, K., Kumar, D., et
al. 2010), this includes Biotolerant (stainless steel, chro-
mium-cobalt alloy), Bioinert (titanium alloy, pure tita-
nium, carbon) and Bioactive (hydroxylapatite, ceramic
oxidised aluminium).
• Based on diameter: The diameter usually ranges from 1.0
to 2.0 mm. reaching 3 to 4 mm in the palatal implants
(Mizrahi, E. and Mizrahi, B. 2007).
• Based on length: The length of a TAD refers to the length
of the threaded body. They are typically available in 6, 8,
10, and 12 mm but range from 4 to 21 mm.
• Other design features such as thread depth, thread de-
sign, pitch (number of threads), taper (conical vs cylin-
drical), flute (fluted vs not fluted), head design and pre-
drilling vs self-drilling.
Characteristics for ideal TADs
These include:
• Biocompatible
• Low cost
• Acceptable for patients – no discomfort during in-
sertion, use or removal
• Accept direct and indirect loading of force
• Versatile and convenient for insertion in a wide va-
riety of sites without damage to adjacent vital struc-
tures (e.g. teeth)
• Convenient for application of orthodontic forces by
a variety of means and in a variety of directions
Osseointegrating screws
Osseointegration is the direct structural and functional con-
nection between living bone and a load-bearing artificial
implant (Albrektsson, T., Brånemark, P.-I., et al. 1981). Os-
seo-integrating anchorage devices require surgical removal
following use. Osseointegrating screws can withstand high
forces and can provide absolute anchorage. However, osseo-
integrating screws are required traumatic insertion and re-
moval as a surgical procedure are needed. Apart from specific
circumstances where immediate loading is feasible, there is
an increased waiting period before loading is mandatory (at
least 12 weeks) (Esposito, M., Grusovin, M.G., et al. 2013).
Types of osseointegrating screws
These include:
1. Mid-palatal implants are usually supplied as cylin-
drical implants with 4 to 6 mm (mostly 6) length (Wehrbein,
H., Feifel, H., et al. 1999) and 3-4 mm in diameter: (Tins-
ley, D., O’Dwyer, J., et al. 2004). The mid-palatal implant is
usually inserted 6 to 9 mm posterior to the incisive foramen
posterior to the interconnecting line of the first premolars
(Kinner, F. and Schlegel, K.D. 2002). They are placed in the
anterior palatal vault(Tinsley, D., O’Dwyer, J., et al. 2004).
It is recommended to avoid midpalatal insertion in patients
below 17 due to the high risk of failure as the suture is im-
mature (Bernhart, T., Vollgruber, A., et al. 2000). Mid-pal-
atal implants are used for distalization of molars, enmass
retraction of the anterior segment and protraction of poste-
rior teeth. The main advantages of mid-palatal implants are:
• It withstands greater orthodontic forces.
• It provides almost absolute anchorage.
• It is placed away from the roots of teeth.
• High success rate, up to 89.5% (Schätzle, M., Män-
nchen, R., et al. 2009)
While the disadvantages of mid-palatal implants are:
• Higher cost
• Osseointegration means a need for waiting time be-
fore loading and traumatic removal.
• Risk of anterior teeth roots damage if placed too an-
teriorly.
• There is a high failure rate in the mid-palatal suture
(Bernhart, T., Vollgruber, A., et al. 2000).
2. Onplants are subperiosteal titanium alloy disks

Temporary Anchorage Devices 81
coated with hydroxyapatite on one side (Block, M.S. and
Hoffman, D.R. 1995). Onplants are flatform (coin-shaped),
2mm thick and 10 mm wide. The side facing bone is textured
and coated with a 75 ~µm thick hydroxyapatite layer. The
other side facing soft tissue is smooth titanium alloy with an
internally threaded hole at its centre into which abutments
can be placed. Onplants are usually placed in the palate or
at areas with little bone. The advantages of Onplants are:
• Since it is not inserted into the bone, it is considered
less invasive and doesn’t need extra bone thickness
for insertion.
• It can be placed during various states of dental erup-
tion to avoid damages to the unerupted and erupted
teeth.
• High success rate up to 82.8% (Feldmann, I. and
Bondemark, L. 2008).
The disadvantages of Onplants are:
• Osseointegration means a need for waiting time be-
fore loading and traumatic removal.
• Expensive and not available commercially
• Two soft tissue surgical procedures are required, one
for placement and one for removal.
Mechanically retained screws
Primary mechanical stability is provided by direct contact of
the TAD with bone. Hence, it doesn’t depend on osseointe-
gration. The advantages of mechanically retained screws are:
• Immediate loading is possible, i.e. same day of inser-
tion and early loading.
• No osseointegration is associated with these types of
screws. Therefore, their removal is more straightfor-
ward.
The disadvantages of mechanically retained screws are:
• They withstand lower forces compared to osseointe-
gration devices
• Their insertion technique is sensitive and usually as-
sociated with a steep learning curve.
Types of mechanically retained screws
• Miniplates are titanium miniplate with two or more
screws attached to the bone (Sugawara, J. 2014).
They are provided in different shapes, L-, Y- or T-
shaped with the long T- or L-arm emerging through
the mucosa and providing the point of attachment
for the traction force. Miniplates can be inserted in
different regions including:
• Zygomatic buttress
• The lateral wall of the piriform aperture rim
• The mandibular basal bone
• The anterior border of the mandibular ramus
• Symphysis (Çubuk, S., Kaya, B., et al. 2019)
The indications of miniplates are:
• Intrusion of molars bloc, up to 5mm, for correction
of an AOB (Sugawara, J. 2014).
• Enmass distalization of maxillary and mandibular
teeth.
• Cases where insertion of mini-screws is not feasible.
• In orthognathic surgery, first cases (i.e. surgery pre-
cedes decompensation).
• To achieve an orthopaedic effect, for example, pro-
traction of maxilla in growing patients (Bollard
miniplates) (De Clerck, E.E. and Swennen, G.R.
2011). The advantages of miniplate are:
• The risk of root damage is low (Sherwood, K.H.,
Burch, J., et al. 2003).
• A variety of convenient shapes and sizes are avail-
able.
• They are easily adaptable to most bony surfaces.
• The varying shapes allow the force vector to be
brought near the occlusal plane, avoiding unwanted
intrusion.
• There is a high percentage of success up to 93% (Fin-
dik et al., 2017).
• They have a higher load-bearing capacity than mini-
screws (Baumgaertel, S. 2014)
The disadvantages of miniplate are:
• Expensive
• It requires postponing the orthodontic load by 2-3
weeks for the mucosal flaps to heal (Cha, B.-K.,
Choi, D.-S., et al. 2011).
• Limited places for insertion
• More invasive and requires flap reflection in place-
ment and retrieval.
• Patient discomfort associated with the placement,
maintenance, and removal of the plates (Sherwood
et al., 2003)
• It may need another operator to install (surgeon/im-
plantologist).
2. Mini-screws are small bone screws placed in at-
tached gingivae, engaging with cortical and cancellous bone,
like temporary anchorage devices in orthodontic treatment.
They are also called orthodontic mini-implants (OMIs),

82
mini-screws implants (MSIs) and temporary anchorage
devices (TADs). Miniscrews are made of three main parts:
• Head (various designs) to connect to orthodontic
appliances
• Trans-mucosal collar, that traverses the mucosa
• Intraosseous thread
The indications of miniscrews are:
A. Antero-posterior anchorage (Cousley, R.R. 2015a, Cous-
ley, R.R. 2015b) including:
• Bodily incisor retraction and torque control
• Molar protraction
• Molar distalization
• Uprighting tipped molars
B. Vertical anchorage (Cousley, R.R. 2015a, Cousley, R.R.
2015b) includes:
• Molar or posterior segment intrusion
• Anterior segment intrusion
• Traction of impacted teeth
C. Transverse anchorage (Cousley, R.R. 2015a, Cousley,
R.R. 2015b) includes:
• Used with expansion devices in bilateral and unilat-
eral expansion
• Assisting in midline correction
D. Other applications (Cousley, R.R. 2015a, Cousley, R.R.
2015b) include:
• TAD-supported pontics for missing teeth.
• Attachments for elastics in condylar fractures in
young patients, especially those in whom all perma-
nent dentition has erupted.
• Intermaxillary fixation In orthognathic surgery cas-
es.
The contraindications and limitations of miniscrews are:
• It is not recommended to place a mechanically-re-
tained screw in patients below the age of 12 (juve-
nile patients) who have not completed the majority
of their skeletal growth (Kravitz, N.D. and Kusnoto,
B. 2007),
• Patients who smoke.
• Patient taking bleeding disorders & anticoagulant
treatment
• Patient with endocarditis (requires antibiotic pro-
phylaxis) (Leong, J.W., Kunzel, C., et al. 2012)
• Immuno-compromised patients
• Patient with uncontrolled diabetes mellitus
• Patient with titanium allergy
• Patient with generalised or localised bone pathology,
e.g. severe osteoporosis, bisphosphonate treatment,
radionecrosis, etc.,
• Patients with poor oral hygiene or local infection.
The advantages of miniscrews are:
• Safe to use
• Low cost
• Orthodontists can place them
• They usually placed under local anaesthetic
The disadvantages of miniscrews are:
• Their insertion is technique sensitive
• Limited suitable sites for insertion
• Potential to fracture 3%
• Damage to the vital structures, including tooth
roots. It has been reported that 21% of the inserted
TADs by inexperienced users had root contact com-
pared to 13% with experienced users.
• Higher risk of failure: Most studies reported various
success rates, 87% (Papageorgiou, S.N., Zogakis, I.P.,
et al. 2012) and 86.7% (Alharbi, F., Almuzian, M.,
et al. 2018).
Stability & failure of mini-screws
A. Stability of miniscrews: Primary stability is the degree
of mechanical interlocking immediately following TADs
insertion. It plays a vital role in both the implant’s short and
long-term success (Nienkemper, M., Wilmes, B., et al. 2014).
Secondary stability is a biological term related to the degree
of implant/bone integration (Breinemark, P., Adell, R., et al.
1969). Secondary stability depends on bone density, bone
quality, implant topography and patient-related factors such
as age and medical condition. Secondary stability reaches
the maximum after 4-5 weeks following mini-screw inser-
tion.
• Failure of the miniscrews: Successful miniscrews
are those which remain stable (static) under nor-
mal orthodontic force application (e.g. 150−200 g)
for a minimum of six months (Cousley, R.R. 2015b).
Failure in miniscrews typically manifests as either
noticeable lateral mobility or excessive peri-implant
soft tissue swelling/hyperplasia. Patients rarely pres-
ent with acute pain related to peri-implantitis. Sup-
pose the miniscrew appears to be clinically immo-
bile and asymptomatic after two to three months. In

that case, it is unlikely to develop problems under
normal orthodontic loading as most failures occur
within the first few months of insertion.
Factors affecting failure of miniscrews
These include:
A. Patient (anatomical) factors (Cousley, R.R. 2015b)
1. Somatic and general factors such as gender and age.
However,nosignificantdifferencewasfoundbetweengenders
(Mohammed, H., Wafaie, K., et al. 2018). It has also been re-
ported that adults have a higher success rate than adolescents
(Motoyoshi, M., Matsuoka, M., et al. 2007) due to higher levels
of cortical thickness and density and lower rates of bone re-
modelling in adults (Mohammed, H., Wafaie, K., et al. 2018).
2. Skeletal features: It was stated that high angle cases
have high failure rates than low angle cases due to a thinner
corticalplateinhighanglecases.However,literaturereporteda
weak correlation between the failure of TADs and the vertical/
sagittal relationship (Mohammed, H., Wafaie, K., et al. 2018).
3. Insertion site anatomy: Insertion of the minis-
crews in the area of keratinised attached gingiva is associ-
ated with a higher success rate than non-keratinized free
gingiva as the former prevents tissue overgrowth (Park, H.-
S., Jeong, S.-H., et al. 2006). Moreover, it is recommended
to provide a minimum of 0.5 mm of TADs-root separation.
Contact between the miniscrew and the root induces unfa-
vourable ‘jiggling’ forces, which affect the blood supply and
the bone remodelling (Mohammed, H., Wafaie, K., et al.
2018). Root contact occurs due to incorrect initial insertion
point, anatomical variation of root morphology and pro-
gressive tooth movement after insertion (Mizrahi, E. 2016).
4. Bone characteristics include cortex thickness
and density. Regarding cortex thickness (quantity), 1−2
mm depth of cortex appears ideal for primary stabil-
ity. More than 2mm leads to greater stress concentration
on the cortical plate. While cortex might resorb, cancel-
lous bone aids in secondary stability by remodelling at the
compression side of orthodontic tooth movement. More-
over, high cortex density (quality) results in better stability.
5. Mini-implant (design) factors such as:
• Material of the TADs: Grade V machined (smooth)
titanium alloy and stainless steel are acceptable.
• Type of drilling: Self-drilling performed better than
pre-drilling during the primary stability phase, but
no difference was reported regarding secondary sta-
bility.
• Size of the TADs: 1.4 mm diameter and 6-8mm
length are preferable option for inter radicular Tads
(Park, H.-S., Jeong, S.-H., et al. 2006).
B. Clinical (insertion and loading) factors such as
• Insertion speed should be below 150 rpm.
• Insertion torque (IT) should be 5 ~ 15 Ncm. IT <
5 has low 1o stability while IT > 15 leads to micro-
cracks, pressure necrosis and decreased secondary
stability.
• Insertion forearm/ wrist rotation torque and speed
should be minimised.
• Insertion angle of 60° to 70°is preferable (Wilmes,
B., Su, Y.Y., et al. 2008).
• Loading force: immediate loading of 50 g showed
better bone-implant contact while a load more than
200 gm doesn’t affect the primary stability (Cris-
mani, A.G., Bertl, M.H., et al. 2010).
• Operator related factors: It has been reported that
21% of the inserted TADs by inexperienced users
had root contact compared to 13% with experienced
users. Furthermore, TADs inserted on the left side
have better success rates due to the brushing bias of
right-handed people (Park, H.-S., Jeong, S.-H., et al.
2006)
The failure rate of miniscrews according to the site of in-
sertion
In summary, insertion of TADs in (Mohammed, H., Wafaie,
K., et al. 2018):
• The palatal sites (Mid-palatal, Paramedian and Para-
palatal) has a success rate of 95.3%.
• The maxillary buccal sites (between teeth 6-5, be-
tween 3-2 and zygomatic buttress) has a success rate
of 90.4%
• The mandibular insertion sites (between teeth 6-5
and 3-4) has a success rate of 87.7%.
Special features in the miniscrews
These include:
• Pre-drilling: Pre-drilling TADs have a blunt tip, so a
predrilling pilot hole is required. It is recommended
for areas with high bone density and when the inser-
tion angle is oblique to prevent slippage of the screw
on insertion.
• Self-drilling has a sharp tip; therefore, no pre-drill-
ing nor pilot hole is required (Kim, J.-W., Ahn, S.-J.,
et al. 2005). The tip of these TADs is either tapered
or have a notch (flute) at the end that helps in drill-
ing. It has been reported that self-drilling provide
better bone screw contact and primary stability with
less chance of root damages (Kim, J.-W., Ahn, S.-J.,
et al. 2005). Compared to pre-drilling, self-drilling
is less expensive, require a shorter operation time,
produces less thermal damage & bone morbidity

84
with minimal patient discomfort (Kim, J.-W., Ahn,
S.-J., et al. 2005).
• Self-tapping: All current miniscrews are self-tap-
ping. Both pre-drilling and self-drilling require no
separate tapping of a thread. The potential confusion
is that some authors use self-tapping as a synonym
for the pre-drilling (Chen, Y., Shin, H.-I., et al. 2008).
• Pitch is the distance between the threads of the
mini-screws, and it should be about 1mm (Brinley,
C.L., Behrents, R., et al. 2009).
• The flute is a depression made longitudinally at the
cutting end; fluting increases the primary stability
(Brinley, C.L., Behrents, R., et al. 2009)
How to optimise the success rate of miniscrews?
These include:
• Site selection: In the maxilla, the ideal insertion sites
are between 6-5, 2-3, extraction space of a molar, in
the palate and infra-zygomatic crest. In the mandi-
ble, the ideal insertion sites are between 6-5, 3-4 and
the extraction space of a molar. It is recommended
to avoid the placement of a miniscrew in the mid-
palatal suture as the suture may be incompletely cal-
cified. The para-palatal area can be utilised to insert
TADs in the palate’s lateral borders. This insertion
site has been widely used for intrusion purposes of
the posterior maxillary teeth. The failure rate for the
para-palatal area was 5.5%—field (Mohammed, H.,
Wafaie, K., et al. 2018).
• Site preparation: The root angulation should be con-
firmed radiographically before insertion. If a TAD
is to be placed mid-treatment and there is doubt re-
garding root position from the initial OPG, a peri-
apical radiograph should be taken. Ideally, a space
greater than 1.5mm should be present between the
TAD and each root (Baumgaertel, S. 2014). Clinical
techniques often involve diverging adjacent roots to
increase the interproximal space before mini-screw
insertion.
• Minscrews selection according to the location: For
miniscrew insertion in the alveolar bone (inter ra-
dicular), a self-drilling using the smallest size within
the acceptable limits is recommended. Inserting the
miniscrew in a dense cortical bone (e.g. buccal shelf)
requires pre-drilling along with the use of a large-
sized miniscrew.
• Palatal implant placement: Bone thickness should
be measured to avoid nasal cavity perforation. Mea-
surements can be taken from CBCT or lateral ceph-
alogram (Wehrbein, H., Merz, B.R., et al. 1999). A
safety margin of at least 2 mm is advised.
• Patient preparation for TAD insertion: The patient
is instructed to rinse with a chlorhexidine solution.
A local anaesthetic gel is applied topically. A typi-
cal compound anaesthetic cream comprises 20% li-
docaine, 4% tetracaine, and 2% phenylephrine. A
small amount (e.g. 0.1−0.2 ml) of local anaesthesia
is needed when the mucosa is thick or highly kera-
tinised.
• A clinical technique during the insertion of the
mini-screw: The insertion point should be as high
as possible to decrease the risk of root contact but in
the attached keratinised mucosa (Park, H.-S., Jeong,
S.-H., et al. 2006). To reduce the chance of root con-
tact, it is advisable to start with 90 degrees insertion
angle; then, after penetrating the cortical bone layer,
the insertion angle is changed to 70 degrees. Inser-
tion should be stopped, and the insertion point/
angle is changed patient has significant discomfort
(indicating root approximation), there is increased
resistance indicating root contact. If an implant fails
at a site, a new implant with a larger length or diam-
eter should be used.
• Loading of the mini-screw: Immediate loading with
force < 200gm is associated with a high success rate
of the miniscrews (Costa, A., Raffainl, M., et al.
1998).
Post-operative instructions
These include
• The patient should be instructed to use a chlorhexi-
dine mouthwash to rinse around the miniscrew
twice daily for the first 5 days.
• The patient should be advised to gently brush around
the miniscrew twice daily using a fluoride toothpaste
and a small-headed toothbrush,
• The patient should avoid using an electric tooth-
brush around the miniscrew and avoid ‘fiddle’ with
it with your fingers or tongue!
• Patients should be informed that the miniscrew may
feel slightly loose at first; however, if the miniscrew
becomes very loose or the brace becomes detached,
they should contact their orthodontist immediately.
Direct Vs indirect anchorage
Direct anchorage in which the force system extends directly
between the TAD and the dental unit to be moved. Force
systems include compression spring, tension spring, elastic
chain, active wire ligature etc. It is essential to consider the 3D
location of TADs about the centre of resistance of the tooth/
group of teeth to be moved (Ozkan, S. and Bayram, M. 2016).
Indirect anchorage in which the TAD stabilises the dental unit
creates an implant-reinforced dental anchorage unit and pro-

vides absolute anchorage. The mechanics used for indirect an-
chorage include incorporating rigid steel wire with cross tubes
or double tube, acid etches technique, connection with TPA/
quad helix or wire ligatures (Ozkan, S. and Bayram, M. 2016).
The advantages of direct anchorage are that the technique re-
quires simple activation, including efficient mechanics with
minimal anchorage loss and less chairside time. On the other
hand, the benefits of indirect anchorage are that less load on
the screw is needed, if the connection is rigid, it can with-
stand more forces, and it is considered a fail-safe mechanic.
The disadvantages of direct anchorage are that greater load is
applied, which might cause mobility or loss of the screw, poor
force control. Furthermore, the mechanics are not fail-safe
with less vertical control. The disadvantages of indirect an-
chorage are anchorage loss as the implant might suffer from
unnoticed breakage. With indirect anchorage, taking support
from the implant is slightly complicated and time-consuming.
Bicortical anchorage
Bicortical anchorage can increase the chances of success and
primary stability (Brettin, B.T., Grosland, N.M., et al. 2008).
To obtain bicortical anchorage, it is essential to objectively
measure the buccolingual width of the alveolus. TAD with a
length equal to or slightly shorter than this length is chosen.
For bicortical anchorage, TAD is inserted from the buc-
cal side while palpating the lingual side; once the tip of the
screw is palpated from the lingual, insertion is stopped, and
bicortical engagement is achieved. To avoid inflammation
and patient discomfort, some recommend slightly counter-
clockwise unthreading after bicortical engagement.
Complications associated with TADs
These include:
• Root trauma: If the TAD comes very close to a root, it
should be removed, and repair will occur over time.
However, if damage has happened to the pulp, the
chances of healing and repair are less likely (Alves Jr,
M., Baratieri, C., et al. 2013),
• Implantation in the nasal or maxillary sinus
• Trauma to the nerve e.g. greater palatine, inferior
alveolar or mental
• Trauma to the blood vessel, e.g. palatine artery
• Mini-screw slippage
• Mini-screw migration
• Fracture of screw up to 3% (Chen, C.-H., Chang, C.-
S., et al. 2006)
• Infection and peri-implantitis
• Soft tissue coverage: It is recommended to select
miniscrews with a large head/ long trans-mucosal
collar to minimise this side effect.
• Local emphysema
Exam night review
Materials
• Biotolerant (stainless steel, chromium-cobalt alloy)
• Bioinert (titanium alloy, pure titanium, carbon)
• Bioactive (hydroxylapatite, ceramic oxidised alu-
minium)
Characteristics for ideal TADs
• Biocompatible
• Low cost
• Easy at insertion and removal
• Minimal damage
Classification of TADS
• Osseointegrating
• Midpalatal implants
• Onplants
• Mechanical retention
• Miniplates
• Mini-screws
Mid-palatal implants
• Length 4 to 6 mm (mostly 6)
• Form cylindrical
• Diameter 3 to 4 mm
• Success rate: 89.5% (Schatzle et al., 2009)
Indications
• Distalization of molars
• Retraction of the anterior segment
• Protraction of posterior teeth
Miniplates (Sugawara, 2014)
Region of insertion
• Zygomatic buttress
• Piriform aperture rim
• Mandibular basal bone
• Anterior border of the mandibular ramus

86
• Patient discomfort (solution: prescribe analgesics if
required)
• Symphysis
Success rate: 92.5% (Findik et al., 2017) to 92.7% (Schatzle et
al., 2009)
Indications
• Intrusion of molars
• En-mass distalization
• when mini-screws are not feasible
• Before decompensation, i.e. surgery, first orthogna-
thic cases.
• Protraction of maxilla in growing patients
Mini-screws
Success rate: 87% (Papageorgious et al., 2012) and 86.7%
(Alharbi et al., 2018).
Indications;
E. Antero-posterior anchorage :
• Bodily incisor retraction and torque control
• Molar protraction
• Molar distalization
• Uprighting tipped molars
F. Vertical anchorage
• Molar or posterior segment intrusion
• Anterior segment intrusion
• Traction of impacted teeth
G. Transverse anchorage
• Bilateral/unilateral expansion
• Midline correction
H. Other applications:
• TAD-supported pontics.
• Attachments for elastics.
• Intermaxillary fixation In orthognathic surgery
Factors affecting failure of mini-implants (Cousley , 2015a)
Somatic and general factors
• Sex: No significant difference b/w genders
• Age: Adults lower success rate.
• Skeletal features: High angle cases have high failure
rates.
Insertion site anatomy
• Soft tissue: insertion in keratinised gingiva → higher
• success rate.
• Root contact causes failure.
• Micro-bone characteristics
• Time factors: Weeks 3 and 4, primary stability re-
duces, but after 4 weeks, stability no change.
• Cortex thickness (quantity)
1−2 mm cortex, ideal for primary stability:
More than 2mm →greater stress concentration.
• Cortex density (quality)
Increased cortical density→ stability
Mini-implant (design) factors
• Material of the TADs: Grade V machined (smooth)
titanium alloy and stainless steel are both acceptable
• Type of drilling: Self-drilling performed better than
pre-drilling during the primary stability phase, but
no difference was reported regarding secondary sta-
bility
• Size of the TADs: 1.4 mm diameter, 6-8mm length
are preferable (Crismani et al., 2010; Park et al.,
2006; Suzuki et al., 2013)
Clinical (insertion and loading) factors
• Insertion speed should be below 150 rpm.
• Insertion torque (IT) should be 5 ~ 15 Ncm.
• IT < 5 has low 1o stability,
• IT > 15 leads to micro-cracks, pressure necrosis and
decreased 2o stability.
• Insertion angle b/w 60° to 70°is preferable (Wilmes,
B., Su, Y.Y., et al. 2008)
• Loading force: immediate loading of 50 g showed
better bone-implant contact.
Other factors
• Operator experience: Inexperienced users mean
high chance of root contact
• Dominant hand side: left side → better success
The failure rate of mini-screws according to the site of inser-
tion (Mohammed et al., 2018)
• Palatal sites (Mid-palatal, Paramedian and Para-
palatal): 95.3%.
• Maxillary buccal sites (b/w 6-5, b/w 3-2 and zygo-
matic buttress): 90.4%.

• Mandibular insertion sites (b/w 6-5 and b/w 3-4):
87.7%.
Advantages of self-drilling
• No drills required
• Better bone screw contact and primary stability
• Fewer root damages
• Less expensive
• Decrease in operation time
• Little bone debris
• Lesser thermal damage & bone morbidity
Complications associated with TADs
• Root trauma
• Implantation in the nasal or maxillary sinus
• Trauma of nerve or vessel.
• Mini-screw slippage.
• Infection.
• Soft tissue coverage
• Mini-screw migration
• 3% risk of fracture of the screw.
• Local emphysema
• Patient discomfort
References
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S0889-5406(Thomas Set al 1998, A.o.t.I.t.a.r.B., 25;275-282)70345-8

90

8
1. Why do we take teeth out?
2. Claimed advantages of the non-extraction ap
proach
3. Claimed advantages of extraction approach
4. Prevalence of extractions in orthodontics
5. Evidence about the detrimental effects of extrac
tion
6. Extraction of primary teeth
7. Guidelines for extraction of primary teeth
8. Extraction of permanent teeth
9. Lower incisor extraction
10. Lower canine extraction
11. Lower first premolars extraction
12. Lower second premolars extraction
13. Lower first molar extraction
14. Lower second molar extraction
15. Upper central incisor extraction
16. Upper lateral incisor extraction
17. Upper canine extraction
18. Upper first premolars extraction
19. Upper second premolar extraction
20. Upper first molar extraction
21. Upper second molar extraction
22. Third molars extraction
In this Chapter
Extraction in
orthodontics
Written by: Mohammed Almuzian, Haris Khan, Aroosh Ahmed

Extraction In Orthodontics
92
Dr Wolf, the physiologist, stated that bone formation was
related to its stress. Dr Angle assumed that bone could sur-
round teeth and stabilise them in their new functional po-
sition. Dr Angle was convinced that the human jaw could
accommodate a full set of teeth in an ideal occlusion. Dr
Angle was also very preoccupied with facial aesthetics and
maintaining the ideal profile, which could be gained from
the ideal positioning of a full complement of teeth. Calvin
S. Case criticises Dr Angle for his non-extraction approach
since it influences the profile (Bernstein, 1992a, Bernstein,
1992b). Around the 1930s, Charles Tweed and Raymond
Begg, both ex-pupils of Angle, were simultaneously revising
their therapies to include extractions after being dissatisfied
with the extent of relapse noted in previous non-extraction
cases. Raymond Begg abandons non-extraction due to high
relapse and accused the loss of interproximal abrasion for the
need for extraction.
Why do we take teeth out?
These include:
• General factors like caries, periodontal problems, or
severe malposition
• Relief of arch length discrepancy
• Correction of incisor relationships and overjet
• For correction of overbite (flattening of the curve of
Spee requires space)
• Reduce the fullness of the lip, e.g., Bimaxillary pro-
trusion
• Correction of midline shift of more than 4mm.
• Allow molar distalization
• Management of tooth size discrepancy
• Provision of anchorage provision and allow the use
of intermaxillary elastic
• Interceptive orthodontic treatment
• Enhance stability (weak evidence)
Claimed advantages of the non-extraction approach
These include:
• Less trauma to the child
• Ease of treatment
• Consumer demand
• Short treatment duration
• Facial fullness gives a youthful profile
• Less iatrogenic effect on TMJ
• Less iatrogenic impact on the vertical relationship
• Less iatrogenic effect on smile width
Claimed advantages of extraction approach
These include:
• Controllable outcomes
• Improved stability
• Reduces the protrusive facial appearance
• Minimal gingival recession
• Tooth size reduction is required to compensate for a
dietary change.
Prevalence of extractions in orthodontics
McCaul (McCaul et al., 2001) found that extraction for orth-
odontic purposes represents 10% of overall extraction in
dentistry. Weintraub (Weintraub et al., 1989) found that the
actual extraction rate is 54% in all orthodontic treatments.
He also found a wide variation in extractions that had no as-
sociation with the year of graduation. Bradbury (Bradbury,
1985) surveyed the teeth extracted by orthodontists in a hos-
pital setting. The first premolars were the teeth most com-
monly extracted tooth (59%), followed by the second premo-
lars (13%), first permanent molars (12%), second permanent
molars (7%), permanent canines (4%), permanent lateral in-
cisors (3%) and the permanent central incisors (1%).
Evidence about the detrimental effects of extraction
These include:
1. Profile: There is a long debate regarding the effects of
extraction on facial profiles. Several comparative studies
(Drobocky and Smith, 1989, Luppanapornlarp and Johnston,
1993, Bishara et al., 1997, Paquette et al., 1992, Bowman and
Johnston, 2000) proved that extraction changes facial profile.
Other studies (Boley et al., 1998, Staggers, 1990, Rathod et
al., 2015, Zierhut et al., 2000) contradict these findings. A
systematic review (Iared et al., 2017) compared premolar ex-
traction versus non-extraction groups and found no signifi-
cant differences between the groups in terms of the aesthetic
outcomes. According to another systematic review (Leonardi
et al., 2010), there is a significant individual variation re-
sponse, and the effects of extraction are small on facial pro-
file. Another review (Konstantonis et al., 2018) showed that
extraction seems to affect facial profile, but the evidence is
low quality.
2. Smile width: Orthodontic treatment involving extrac-
tions has been accused of causing a larger “dark buccal cor-
ridor”, though this claim has been rejected by Johnson and
Smith (Johnson and Smith, 1995) and a systematic review
(Christou et al., 2019) which concluded that extractions do

Extraction In Orthodontics 93
not affect the smile width and buccal corridors area.
3. Vertical Dimension: Dewel (Dewel, 1967) expressed
worries that premolar extraction may tend to deepen the bite,
cause lower incisors to tip lingually, and lead to TMD devel-
opment. On the other hand, Beit (Beit et al., 2017) found that
extraction results in a slight decrease in vertical dimension
while non-extraction treatment increase vertical dimension.
Paquette (Paquette et al., 1992) found no convincing stud-
ies that suggest that vertical dimension is influenced by ex-
traction or non-extraction treatment. Similar findings were
reported by Alkumru (Alkumru et al., 2007). According to
a systematic review (Kouvelis et al., 2018), orthodontic treat-
ment with premolar extractions has minimal effect on the
vertical dimension.
4. TMD: It has been suggested that removal of four premo-
lar teeth before orthodontic treatment can be detrimental to
the orthopaedic stability of the temporomandibular joint as
a result of “over retraction” of the maxillary incisors during
space closure, which displaces the mandible posteriorly (Far-
rar and McCarty, 1982). On the other hand, Kim and col-
leagues (Kim et al., 2002) showed that orthodontic treatment
has little to do with TMDs. According to a Cochrane review
(Luther et al., 2010, Luther et al., 2016), there are insufficient
research data to base our clinical practice on the relationship
of active orthodontic intervention and TMD. At present, the
Cochrane evidence on TMD and orthodontic treatment have
been withdrawn.
5. Effect on the periodontium: Artun (Årtun et al., 1987)
showed that excessive proclination of mandibular incisors
might lead to dehiscence, and the overlying gingiva will be-
come very thin and more susceptible to recession than thick
attached gingivae. According to a systematic review by Aziz
(Aziz and Flores-Mir, 2011), there is some association be-
tween appliance induced labial movement of mandibular in-
cisors and gingival recession in the presence of the following
risk factors:
• A reduced free gingival margin thickness
• Inadequate plaque control
• Aggressive tooth brushing
• Narrow mandibular symphysis
6. Stability and relapse: Some clinicians argue that extrac-
tions minimise relapse. However, it has been shown that
relapse can happen equally in extraction and non-extraction
cases (Little, 1990). Paquette (Paquette et al., 1992) reported
that the Little index in the lower labial segment at recall visits
was 2.9 mm in the extraction group and 3.4 mm in the non-
extraction group. This difference was not significant. Hoyb-
jerg et al. (Hoybjerg et al., 2013) showed that using different
retention regimes in extraction or non-extraction cases has
similar stability outcomes.
7. The outcome of treatment: Ileri (Ileri et al., 2012) ret-
rospectively compared the outcome in treating Class I with
the extraction of 4s, non-extraction, or extraction of single
incisors. They found that the outcome measured on the PAR
basis was better in non-extraction groups.
8. General problems such as extra cost, pain, bleeding,
infection, prolonged treatment, difficulty to close spaces,
intra-oral detrimental effects like potential teeth size discrep-
ancy
Extraction of Specific teeth
The factors that should be kept in mind before planning
extraction in orthodontic cases are:
• Tooth-arch discrepancy: Overall, tooth material ex-
cess should be determined before planning extrac-
tions in orthodontic cases.
• Cephalometric discrepancy: Before planning ex-
traction, the orthodontist should consider the pa-
tient profile, which could be affected by tooth move-
ment after extractions. Studies have shown that for
each 1 mm of retraction of the upper incisor, the up-
per lip could retract by up to 0.3-0.75 mm (Ramos et
al., 2005). Regarding the lower lip, for every 1 mm of
lower incisor retraction, the lower lip retracts by 0.6
mm-0.78 mm (Kusnoto and Kusnoto, 2001).
• Dental asymmetry: Studies have shown that max-
illary midline deviation from facial midline can be
accepted aesthetically if the difference is not remark-
ably great. According to research, the mean clinical
threshold for acceptable dental midline deviation is
2.2 +/- 1.5 mm (Beyer and Lindauer, 1998). Another
systematic review (Janson et al., 2011) showed that
dental midline deviation of 2.2 mm is considered
acceptable by both orthodontists and laypeople,
whereas the axial midline angulation should be less
than 10°. Therefore, evaluating the midline as a sign
of dental asymmetry is one of the major concerns
before planning tooth extractions. Patients present-
ing with severe dental midline deviation to the face
(especially in the lower arch) and arch length dis-
crepancy might require asymmetrical teeth extrac-
tions.
• Pathologies: Some pathologies play a crucial role in
defining orthodontic treatment planning. If teeth
have periodontal problems, abnormal shapes, roots,
and other pathologies, they should be included in
the extraction pattern.
Extraction of primary teeth
• When an orthodontist is dealing with enforced
extraction of a deciduous tooth, a treatment plan
should be made whether to remove the unsavable

94
tooth, extract a contralateral tooth from the same
arch (balance), or extract a tooth from the opposing
arch (compensation).
• Balancing extraction refers to removing a tooth from
the opposite side of the same arch; it is designed to
minimise centerline shift. Compensating extraction
refers to removing a tooth from the opposing quad-
rant to maintain the buccal occlusion by allowing
molar teeth to drift forwards in unison.
Guidelines for extraction of primary teeth
Before planning extraction of primary teeth, it is essential to
undertake a thorough radiographical examination to assess
the presence, position, and formation of the developing
permanent dentition.
• Primary incisor: Early loss of primary incisors has
little effect on the developing permanent dentition,
so it is unnecessary to balance or compensate for the
loss of a primary incisor.
• Primary canine: Early unilateral loss of a primary
canine can result in centerlines deviation, especially
in crowding in the arch, which necessitates the need
for balancing extraction.
• First Primary molar: A balancing extraction may
be needed if the loss is unilateral, specifically in a
crowded arch. If mandibular first deciduous molars
are lost, some consideration can be given to com-
pensating extractions in the maxillary arch to pre-
serve the buccal segment relationship.
• Second primary molar: Balancing the loss of a pri-
mary second molar is not indicated because it has no
appreciable effect on the centerline. However, if they
are lost bilaterally in the upper or lower arch, it can
alter the molar relationship; hence, in these cases,
compensating extractions may be considered.
Extraction of permanent teeth
1. Lower incisor extraction
Indications for lower incisor extraction
These include:
• Signficant tooth size discrepancy (TSD) with man-
dibular tooth size excess (Matsumoto et al., 2010).
• In the presence of poor prognosis of lower incisor
such as a periapical lesion, bony defects, severe gin-
gival recession, heavy restoration, trauma, lost vi-
tality, ectopically erupted or impacted incisor and
abnormal shapes and size such as macrodontia and
microdontia (Bahreman, 1977, Canut, 1996, Kokich
and Shapiro, 1984)
• Mild Class III malocclusion combined with a re-
duced overbite, increased inter-canine width, distal
tipping of the canines, minor crowding and tooth
excess in the lower arch may justify lower incisor ex-
traction (Zhylich and Suri, 2011, Faerovig and Zach-
risson, 1999).
• Class I malocclusion with a well-aligned upper arch,
good intercuspation in the buccal segment but local-
ised lower incisor crowding (Faerovig and Zachris-
son, 1999). In such cases, it has been reported that
single incisor extrcation is asscoiated with reduced
treatment duration comapred to premolars extrac-
tion (DiBiase et al., 2011) and reduced anchorage
demand due to the locked posterior occlusion.
• Class II malocclusion with full unit class II molar
relationship, increased overjet, and severe upper
and lower arch crowding that need extraction. These
cases can be treated with upper premolar extraction
and single lower incisor extraction. Studies suggest
that in such patients, the long term stability is better
than the traditional four premolars extraction (Lv et
al., 2010).
Contraindications for lower incisor extraction (Hegarty and
Hegarty, 1999)
These include:
• Excessive overbite and overjet.
• Poor buccal segment relationship.
• Patients are having mesially angulated canines.
• Poor prognosis of posterior teeth.
Problems associated with lower incisor extractions
These include:
• Reduced lower intercanine width.
• Lower midline discripnacy due to asymmetric ex-
traction.
• Increases in the overbite and overjet.
• Needs for fixed appliance therapy to allow con-
trolled bodily movement of the incisors.
• Difficulty in achieving a good occlusal fit.
• High risk of space reopening (Dacre, 1985).
• Post-treatment black triangle due to loss of the in-
terdental papilla which can be managed by (a) off-
setting the brackets adjacent to the extraction site to
indcue mesial tipping of the roots and (b) wire bend-
ing or (c) root uprighting springs.
• Iatrogenic TSD, hence, Bolton’s analysis is essential
to be undertaken before extraction. TSD can be
managed by (a) performing upper IPR, (b) sawp-

ping upper canine brackets, (c) using low torque
upper anterior brackets, (d) inverting lower incisors
brackets, (e) using lower canine brackets with Roth
prescription and (f) using Class II elastics.
2. Lower canine extraction
The mandibular canine is rarely extracted because it has a
very good length and is functionally and aesthetically sig-
nificant. However, an extraction might be considered if it is
ectopically eruption, hypoplastic or periodontally compro-
mised with grade III mobility.
3. Lower first premolars extraction
Indications for lower first premolars extraction
These include:
• First, premolars are the most frequently extracted
teeth in orthodontic cases because they allow bal-
anced posterior anchorage and help in maximum
retraction of anterior teeth (Bradbury 1985).
• In patients with Class I malocclusions with upper
and lower arch crowding.
• In patients with Class II molar relationship, severe
lower arch crowding and decreased overjet.
• In patients with Class III molar relationship, mild
upper arch crowding and reverse or reduced overjet.
• Extraction of premolars can be part of the serial ex-
tractions plan.
• Contraindications for extractions
• These include:
• Risk of excessive lingual movement of lower incisors
• Mild crowding in the lower arch
• When other teeth also have a poor prognosis.
4. Lower second premolars extraction
Indications for for lower second premolars extraction
These include:
• Lower premolars with hypoplasia, pathology, peri-
odontally involved or ectopically erupted.
• To relieve mild-moderate crowding in the lower
arch.
• To avoid excessive lingual movement of lower inci-
sors.
• To correct molar relationship and posterior crowd-
ing.
• Balancing extraction in cases with developmentally
missing lower second premolars.
• Extraction of a mandibular second premolar is as-
sociated with rapid space closure, so in theory, it has
minimal effect on profile in patients with a flat pro-
file.
5. Lower first molar extraction
Indications for first molar extraction
These include:
In certain orthodontic cases, extraction of lower first molar
is necessary, but before planning extraction of poor prog-
nosis lower first molars, certain factors should be kept in
mind such as the age of the patient, inter arch relationship,
developmental status, and inclination of the second molars,
presence, and condition of other teeth and angulation of the
second premolars.
Indications of lower first molars
These include:
• Extensive caries or pathologies. For details, read the
chapter of the first molar of poor prognosis.
• Hypoplastic molars- linked with molar incisor hy-
poplasia.
• Heavy restoration.
• In high-angle cases.
• Sometimes extraction of the lower first molar may
be prescribed to prevent the impaction of the third
molar and therefore create space for their eruption
(Bayram et al., 2009).
Contraindications for first molar extraction
These include:
• Third molars are congenitally missing.
6. Lower second molar extraction
Indications for second molar extraction
These include:
Lower second molars are rarely extracted for orthodontic
purposes; however, in some circumstances, their extraction
is indicated such as:
• When they are severely displaced.
• When they have hypoplasia, they are heavily re-
stored or have a poor prognosis.

96
• Sometimes their extraction is undertaken to relieve
crowding in posterior teeth such as premolar crowd-
ing or if the premolar is vertically impacted in the
line of the arch (Kenrad et al., 2011).
• Minimal crowding is present.
Contraindications for second molar extraction
These include:
• Third molars are developmentally absent
• Lower anterior crowding is greater than 1-2mm.
Advantages of second molar extraction (Bishara SE & Bur-
key P 1986)
These include:
• Reduce the need to extract 3rd molar surgically.
• Limit the morbidity associated with lower third
molar extraction.
Disadvantages of second molar extraction
These include:
• The third molar can erupt into an undesired posi-
tion (Gooris et al., 1990). Hence, a mechanical erup-
tion of the third molar using fixed appliance therapy
might be required (Orton and Jones, 1987).
• Much research has been conducted for the unsat-
isfactory eruption of 3rd molars secondary to the
extraction of second molars with a wide range of
discrepancies ranging from 2-4% (Cryer, 1967)
(Richardson and Richardson, 1993) to 20% (Dacre,
1987).
7. Upper central incisor extraction
Extraction of the central incisor is uncommon in orthodon-
tics, but there are some situations where its extraction can be
considered. Before planning its extraction, an orthodontist
should plan the replacement therapies for the extraction
space. In most cases, lateral incisors can be substituted in
their place. Space can also be replaced with implant, pros-
thesis or transplant (Amos et al., 2009). The indications for
upper central incisor extraction are:
• Poor prognosis, including hypoplasia, caries or trau-
ma (Bishara SE & Burkey P 1986).
• When the upper central incisors are malformed.
• When upper central incisors have severe displace-
ment.
8. Upper lateral incisor extraction
Indications for upper lateral incisor extraction
These include:
• If maxillary central incisor and maxillary canine are
in good contact, but lateral incisor is blocked out.
• Upper lateral incisor with severe hypoplasia.
• Abnormalities in shape and size, such as peg-shaped
lateral incisor.
• Root resorption due to ectopic eruption of maxillary
canines.
• Severe ectopic eruption of the lateral incisor.
• When the contralateral lateral incisor is develop-
mentally absent.
Contraindications for for upper lateral incisor extraction
These include:
• If the crown of the canine is bulbous, than the cen-
tral incisor.
• When the shade of the upper canine is significantly
dark.
• When the gingival margin height of the maxillary
canine differs considerably from the upper central
incisor.
• In Class III incisal relationship.
9. Upper canine extraction
Indications for upper canine extraction
The maxillary canine is rarely extracted because it is func-
tionally and aesthetically significant. Here are some indica-
tions for extraction of maxillary canine:
• If maxillary lateral incisor and maxillary first pre-
molar are in good contact, the upper canine is se-
verely displaced from the arch line.
• If the upper canine is ectopically erupted and unfa-
vourable for alignment (sector 5, alpha angle greater
than 55) in this case, its extraction is indicated.
• If the maxillary canine undergoes some pathology
with a poor prognosis or abnormal shape.
• When the patient is unwilling to consider a long
treatment time to align an impacted canine.
10. Upper first premolars extraction
Indications for upper first premolars extraction
The first premolars are considered to be one of the most
commonly extracted teeth in orthodontics (59% of overall
extraction for orthodontic purposes), followed by sec-
ond premolars (13%) and first permanent molars (19%).
The high percentage of first premolar extraction is related
to its position in the arch and the timing of its eruption.
Moreover, its extraction is well accepted in treating cases

of malocclusion that include severe crowding, unilateral
agenesis, bimaxillary protrusion, convex facial profiles, and
large cephalometric discrepancies in borderline cases. The
benefits of first premolar extraction are that second premo-
lars easily substitute them from aesthetic and functional
points of view. A good contact point is established between
the canine and second premolar. Another advantage of first
premolar extraction is that good anchorage balance is easily
achieved.
The following are indications for maxillary first premolar
extraction:
• When upper first premolar has hypoplasia, severely
displaced, transposition cases and has a poor prog-
nosis.
• The first premolar is often ideal in relieving anterior
and posterior crowding.
• As part of the serial extractions plan.
• Midline correction.
• Correction of overjet.
• Anchorage balance.
• Correction of incisor inclination.
• For levelling of the curve of Spee.
• For surgical decompensation.
11. Upper second premolar extraction
Indications for upper second premolar extraction
These include:
• If crowding (mild anterior crowding) or overjet is
moderate.
• Extraction of an upper second premolar is preferred
over the first premolar if the aim is to minimise over
retraction of the labial segment. Hence, its extrac-
tion is useful with Class Ill malocclusions.
• If there is early loss of E and the second premolar
has limited space to erupt and are ectopically erupt-
ed, its extraction is indicated.
• If the maxillary second premolar is impacted, hypo-
plastic, small size, heavily restored, or poor progno-
sis.
• When the second premolar has severe displace-
ment.
• In patients who have congenitally missing second
premolars on the contralateral side, extraction is
advocated for symmetry of molar relationship. This
belief is usually not well accepted.
• In Class II surgical cases, extraction of upper second
and lower first premolars are done to aid in decom-
pensation of the arches.
• In cases where lower premolar extraction is advised,
lower 8s are missing. Upper 2nd premolars are ex-
tracted to prevent extrusion of upper 7s.
• If there is good interproximal contact between the
upper first premolar and the molar, then a maxillary
second premolar is recommended.
12. Upper first molar extraction
Indication for upper first molar extraction
These include:
• If the upper first molar is carious, it has hypoplasia
or large restoration.
• As compensation for the removal of the lower first
molar.
• To relieve posterior crowding.
13. Upper second molar extraction
Indications for upper second molar extraction
These include:
• To aid the distal movement of the upper buccal seg-
ments with extraoral traction.
• When upper second molars have a poor prognosis,
grade III mobility or severe hypoplasia.
• Extraction of the upper second molar helps third
molars to erupt in a more stable and satisfactory
position and hence accelerates their eruption and
decreases their chances of impaction (Bayram et al.,
2009).
Contraindications for upper second molar extraction
These include clinical cases having heavily restored the first
molar and congenitally missing third molars, extraction of
maxillary second molar is contraindicated.
Third molars extraction
There is a wide range of variation in formation and calcifica-
tion, crown and root morphology, eruption and presence or
absence of third molars. As third molars erupt, they need to
create space in the alveolar arch, and sometimes, this process
can lead to crowding in the anterior teeth (Almpani and
Kolokitha, 2015). On the other hand, 13-15% of mandibular
third molars are congenitally missing or become impacted.
The following are some indications for the extraction of
third molars.
• When they have unrestorable caries or non-treat-

98
EXAM NIGHT REVIEW
Extraction in orthodontics
Why do we take teeth out?
• General factors like caries, periodontal problems, or
sever malposition
• Relief of arch length discrepancy
• Correction of incisor relationships and overjet
• For correction of overbite (flattening of the curve of
Spee requires space)
• Facial aesthetic purpose by reducing the fullness of
the lip, e.g., Bimaxillary protrusion
• To allow molar distalization
• Management of tooth size discrepancy
• Provision of anchorage provision and allow the use
of intermaxillary elastics.
• Interceptive orthodontic treatment
Extraction of primary teeth
• Balancing extraction →Ext. of the opposite side of
the same arch →to minimise centerline shift.
• Compensating extraction→Ext. in opposing quad-
rant to maintain the buccal occlusion.
• Guidelines for extraction of primary teeth
• Primary incisor → No need of balancing/ compen-
sating extractions.
• Primary canine →To prevent centerlines deviation in
crowding which necessitate balancing extraction.
• First Primary molar→Balancing extraction in
crowded arch. Compensating extractions in uppers
to preserve the buccal relationship.
• Second primary molar→ No need for balancing ex-
traction, compensating extractions considered.
Extraction of permanent teeth
Indication for lower incisor extraction
• Localised lower arch crowding.
• Poor prognosis
• Mild Class III malocclusion combined with a re-
duced overbite
• Class I Good buccal intercuspation & LLS crowding.
• Full unit class II molars & localised LLS crowding.
Indication for lower canine extraction
Ectopically eruption, hypoplastic or periodontally compro-
mised with grade III mobility
Indication for first premolars extraction
• Class I malocclusions with crowding.
• Class II molar relationship, severe lower arch crowd-
ing.
• In patients with Class III molar relationship, mild
upper crowding
• Serial extractions
Indication for second premolars extraction
• Mild-moderate crowding in lowers
• To avoid retroclinations of LLS.
• To correct molar relationship and posterior crowd-
ing.
• As for balancing extraction.
• Poor prognosis
• Minimal effect on profile.
Indication for the first molar extraction
• Extensive caries or pathologies
• High-angle cases.
• Molar incisor hypoplasia.
• Heavy restoration.
• Prevent impaction of 3rd molar.
Indication for the upper central incisor extraction
able pulpal or periapical pathology.
• In case severe chronic periodontal disease results in
bone loss and recurrent pericoronitis.
• When third molars have external or internal resorp-
tion.
• Any pathalogy of follicle including cyst or tumour.
• When the presence of third molars prevents the
eruption of the second molar.
• When they cause resorption of the second molars.
• When the third molar is impeding surgery or recon-
structive jaw surgery.

• Poor prognosis (pathology/ hypoplasia/caries/trau-
ma.
• Malformed.`
• Severe displacement.
Indication for the upper lateral incisor extraction
• U1 & U3 in acceptable contact blocked out U2.
• Severe hypoplasia, abnormalities in shape and size.
• Root resorption by U3
• Ectopically erupted U2
• Absent contralateral U2.
Indication for the upper canine extraction
• If U2 & U4 are in good contact, the upper canine is
severely displaced from the arch line.
• U3 ectopically erupted, Sector 5, an alpha angle
greater than 55 in this case.
• If the maxillary canine undergoes some pathology.
• Unfavourable impacted / abnormal shape.
• Poor prognosis.
• Patient unwilling for long treatment
Indication for the upper first premolars extraction
• Hypoplasia, severely displaced, transposition cases
and has a poor prognosis
• As part of serial extractions plan
• Midline correction
• Correction of overjet.
• Anchorage balance
• Correction of incisor inclination
• For levelling of the curve of Spee
• For surgical decompensation
Indication for the upper second premolars extraction
• Mild anterior crowding/ moderate overjet.
• Prevents over retraction of ULS
• Impacted U5
• Hypoplastic, heavily restored or have a poor prog-
nosis
• Severe displacement.
• Missing U5 on contralateral side.
• In Class II surgical cases for decompensation.
• Good contact b/w U4 & U6
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9
1. Indications of IPR
2. General advice before commencing IPR procedure
3. Methods of IPR
4. Air rotor stripping (ARS)
5. Long term potential side effects of IPR
In this Chapter
Interproximal Enamel
Reduction
Written by: Mohammed Almuzian, Haris Khan, Hassan Saeed

Interproximal Enamel Reduction
104
Ballard first described Interproximal enamel reduction
(IPR) in 1944 (Ballard, 1944). IPR involves dental width re-
duction, anatomic recontouring and protection of the mesial
and or distal enamel surfaces of a permanent tooth (Peck and
Peck, 1972). IPR can be performed in deciduous and perma-
nent teeth. IPR is also called interdental stripping, enamel
stripping, proximal reduction, reproximation, enamoplasty,
keystoning, enamel approximation and slenderising (Daska-
logiannakis, 2000; Peck and Peck, 1972; Rossouw and Tor-
torella, 2003). Keystoning refers to oblique IPR of the lower
incisors to prevent rotational relapse (Daskalogiannakis,
2000).
Indications of IPR
These include:
1. Improvement of the shape and form of teeth (Sarver,
2011b).
2. Space provision (LR, 1980b; Peck and Peck, 1975; Sheri-
dan, 1985): Theoretically, IPR can provide up to 8mm of
space in total. IPR of the posterior segment can provide up
to 6.4mm of space (0.8mm/contact x 8 contacts). IPR of the
anterior segment can provide up to 2.5mm (0.5mm/contact
x 5 contacts). However, it is recommended to undertake a
conservative IPR of no more than 4mm (Proffit et al., 2007;
Tuverson, 1980) depending on the tooth shape and size (Tu-
verson, 1980). The available spaces from the IPR can be uti-
lised to manage:
• There is a mild degree of incisor proclination, es-
pecially in the clear aligner therapy (Graber et al.,
2012)(Kravitz et al., 2008).
• Shallow overbite (LR, 1980b).
• Mild increase in the overjet (Tuverson, 1980).
• To allow retraction of the upper anterior segment
and eliminate the associated incisor interference
(Sarver, 2011a).
• Asymmetrical dental midlines.
• A mild degree of crowding: Some evidence showed
that space provision via IPR is associated with short-
er treatment duration as the created space is close to
the area of need (Germec and Taner, 2008).
• Mild relapse secondary where IPR is combined with
a clear aligners (Ballard and Sheridan, 1996) or posi-
tioner appliance (Darendeliler, 1998).
3. Enhance stability and reduce relapse tendency: The ratio
of 88-92% and 90-95% for the width/height of upper and low-
er incisors, respectively, is one of the key successes for better
incisor stability. Hence, conservative anterior IPR (1-2mm in
total) can help achieve this ratio, reducing contact points slip-
page and compensating growth-related arch length reduction
(LR, 1980b; Peck and Peck, 1972). Prophylactic IPR can be
prescribed either during the initial alignment phase, imme-
diately after active orthodontic treatment or even 4-6months
post-treatment (LR, 1980b).
4. Interceptive treatment to provide space when extractions
are not planned (Graber et al., 2012) or to premolarise re-
tained primary second molars in cases with missing second
premolars (Graber et al., 2012), hence, achieving Class I mo-
lar relationship (Graber et al., 2012).
5. Management of black triangles or interdental contact ar-
eas by moving the incisal contact point more apically (Saver,
2004).
6. Management of teeth size discrepancy: IPR can be pre-
scribed to improve intermaxillary interdigitation if the
Bolton discrepancy is beyond the average (Bolton, 1962; Ros-
souw and Tortorella, 2003).
7. Canine reshaping in canines substitution cases.
General advice before commencing IPR procedure
IPR should be undertaken sequentially and should be less
than 50% of interproximal enamel to reduce the risk of car-
ies, sensitivity, discolouration, transeptal bone loss, and peri-
odontal disease (LR, 1980b). Trauma to the gingiva should be
avoided. Hence, 0.020-inch wires can be used to protect the
gingiva while performing IPR.
IPR is mainly carried out from posterior to anterior and distal
to mesial contact points. Moreover, IPR has limited applica-
tion in poor oral hygiene, tooth hypersensitivity, hypoplastic
teeth, teeth with high caries risk, small or narrow teeth and
teeth with artificial crowns/ veneers (Jarvis, 1990; Zachris-
son et al., 2011).
Methods of IPR
These include:
1. Air-rotor stripping (ARS) using either (Sheridan, 1985)
using:
• Fine tungsten-carbide.
• Diamond burs with safe-tip to minimise enamel
ledging.
• Diamond-coated stripping discs mounted on slow
speed (30,000 rpm) straight, or contra-angle hand-
piece are called modified Tuverson technique (Tu-
verson, 1980; Zachrisson et al., 2011).
According to a randomised clinical trial (Danesh et al., 2007)
IPR should be followed by thorough polishing while oscillat-
ing systems (Profin, Ortho-Strips, and O-Drive D30).
2. Abrasive strips (Zachrisson et al., 2011; Zhong et al., 2000)
such as:
• Handheld diamond abrasive strips held with the fin-

Interproximal Enamel Reduction 105
gers, a pair of Matthiew’s forceps or a custom saw-
like handle. However, this procedure is less efficient
than ARS (Chudasama and Sheridan, 2007).
• Motor-driven using a reciprocating or oscillating
abrasive diamond strip of various thicknesses.
Air rotor stripping (ARS)
The recommended guideline for ARS include (Chudasama
and Sheridan, 2007):
• Aligning teeth before undertaking ARS.
• Getting visual access to the contact points is recom-
mended using a coil spring or separator for 3-4 days.
• Protection of the interdental tissue using 0.020-
.030” brass, separators, or steel indicator
• Starting IPR from posterior to anterior segment
• Achieving a maximum of 0.5mm per proximal sur-
face or no more than 50% of the enamel thickness.
• Measure the space using a gauge.
• Finish the enamel surface using tapered fissure car-
bide bur and strips to reduce rough surface (Danesh
et al., 2007).
• Polish the enamel using Sof-Lex discs or smoothing
with an acid-based IPR (fine abrasive strip coated
with 35% phosphoric acid gel) (Rossouw and Tor-
torella, 2003).
• Rinse with water spray.
• Undertake a compensatory IPR in the opposing
arch, if required.
• Application of desensitising agents (Jarvis, 1990)
such as Tooth Mousse (Casein phosphopeptide-
amorphous calcium phosphate CPP-ACP), fluoride
varnish (Duraphat varnish) combined with gel/
rinses to assist remineralisation. However, evidence
showed that desensitising agents are not essential in
patients with good oral hygiene (Zachrisson et al.,
2011).
Long term potential side effects of IPR
IPR might increase pocket depths (0.5-1.5mm) (LR, 1980a),
lead to an insignificant decrease in the alveolar crest height
(LR, 1980a) and reduces transeptal bone thickness due to
closer proximity of the adjacent roots. However, the long-
term effects on the health of periodontium are insignificant
(Årtun et al., 1987; Jarvis, 1990). It has been proven that
deep IPR might produce deep interproximal col and non-
keratinised plaque susceptible gingivitis (Jarvis, 1990).
Moreover, IPR might lead to tooth decay, colour changes,
pulpal damage and sensitivity. Evidence showed that IPR
performed using ARS doesn’t cause sensitivity, new cari-
ous lesions, root pathology/ gingival recession (Jarjoura et
al., 2006; Zachrisson et al., 2011; Zachrisson et al., 2007) or
pulp damage (Sheridan, 1985; Zachrisson and Mjor, 1975),
mobility, tenderness to percussion, thermal sensitivity or
negative electric pulp testing results (Thordarson A, 1991).
However, IPR with poor cooling might result in irreversible
pulpal damage (Zachrisson et al., 2011; Zachrisson and Mjor,
1975) and subsequently pulpal inflammatory cell infiltration
(Zachrisson and Mjor, 1975). Some suggested that IPR in the
anterior region could reduce gingival recession as the teeth
can be retracted over the basal bone (Tuverson, 1980).
Exam night review
• IPR can be performed in deciduous and permanent
teeth.
• Ballard first described IPR in 1944 (BALLARD,
1944).
Indications of IPR
• Improvement of shape and form of teeth (Sarver,
2011b).
• Space provision (LR, 1980b; Peck and Peck, 1975;
Sheridan, 1985)
• Enhance stability and reduce relapse tendency (LR,
1980a)
• Interceptive treatment (Graber et al., 2012)
• Management of black triangles (Saver, 2004)
• Management of teeth size discrepancy (Bolton,
1962; Rossouw and Tortorella, 2003).
• Canine reshaping in canines substitution cases.
IPR has limited application in cases with (Jarvis, 1990; Zach-
risson et al., 2011)
• Poor oral hygiene
• Tooth hypersensitivity
• Hypoplastic teeth
• High caries risk
• Small or narrow teeth
• Artificial crowns/ veneers
Methods of IPR
Air-rotor stripping (ARS) using either (Sheridan, 1985).
• Fine tungsten-carbide.

106
References
Årtun, J., Kokich, V.G., Osterberg, S.K., 1987. Long-term effect of
root proximity on periodontal health after orthodontic treatment.
Am. J. Orthod. Dentofacial Orthop. 91, 125-130.
BALLARD, M.L.J.A.o., 1944. Assymetry in tooth size a factor in
etiology, diagnosis and treatment of malocclusion. 14, 67-71.
Ballard, R., Sheridan, J.J., 1996. Air-rotor stripping with the Essix
anterior anchor. J. Clin. Orthod. 30, 371-373.
Bolton, W.A., 1962. The clinical application of a tooth-size analysis.
Am. J. Orthod. 48, 504-529.
Chudasama, D., Sheridan, J.J., 2007. Guidelines for contemporary
air-rotor stripping. J. Clin. Orthod. 41, 315-320.
Danesh, G., Hellak, A., Lippold, C., Ziebura, T., Schafer, E., 2007.
Enamel surfaces following interproximal reduction with different
methods. The Angle orthodontist 77, 1004-1010.
Darendeliler, M.A., 1998. Finishing Checklist.
Daskalogiannakis, J., 2000. Glossary of orthodontic terms, in: van
der Linden, F., Miethke, R.R., McNamara, J.A.J. (Eds.). Quintes-
sence Publishing Co, Inc, Berlin.
Germec, D., Taner, T.U., 2008. Effects of extraction and nonextrac-
tion therapy with air-rotor stripping on facial esthetics in postado-
lescent borderline patients. Am. J. Orthod. Dentofacial Orthop.
133, 539-549.
Graber, L.W., Vanarsdall, R.L., Vig, K.W.L., 2012. Orthodontics
Current Principles and Techniques, 5 ed. Mosby Elsevier, Philadel-
phia, PA.
Jarjoura, K., Gagnon, G., Nieberg, L., 2006. Caries risk after inter-
proximal enamel reduction. Am. J. Orthod. Dentofacial Orthop.
130, 26-30.
Jarvis, R., 1990. Interproximal reduction in the molar/premolar
region: The new approach (review). Aust. Orthod. J. 11, 236-240.
Kravitz, N.D., Kusnoto, B., Agran, B., Viana, G., 2008. Influence of
attachments and interproximal reduction on the accuracy of canine
rotation with Invisalign. A prospective clinical study. The Angle
orthodontist 78, 682-687.
LR, B., 1980a. Fiberotomy and reproximation without lower
retention 9 years in retrospect: part II. The Angle orthodontist 50,
169-178.
LR, B., 1980b. Fiberotomy and reproximation without lower reten-
tion, nine years in retrospect: part I. Angle Orthod. 50, 88-97.
Peck, H., Peck, S., 1972. An index for assessing tooth shape devia-
tions as applied to the mandibular incisors. American Journal of
Orthodontics 61, 384-401.
Peck, H., Peck, S., 1975. Reproximation (enamel stripping) as an es-
sential orthodontic treatment ingredient. C.V. Mosby Co., St. Louis.
Proffit, W., Fields, H., Sarver, D., 2007. Contemporary Orthodon-
tics, 4th ed. Mosby Elsevier, St Louis, Missouri.
Rossouw, P.E., Tortorella, A., 2003. Enamel reduction procedures in
orthodontic treatment. Journal (Canadian Dental Association) 69,
378-383.
• Diamond-coated stripping discs (Tuverson, 1980;
Zachrisson et al., 2011).
Abrasive strips (Zachrisson et al., 2011; Zhong et al., 2000).
• Handheld Diamond (Chudasama and Sheridan,
2007).
• Motor-driven.
Long term potential side effects of IPR
• IPR doesn’t cause sensitivity, new carious lesions,
root pathology/ gingival recession (Jarjoura et al.,
2006; Zachrisson et al., 2011; Zachrisson et al., 2007)
• IPR doesn’t cause sensitivity pulp damage (Sheri-
dan, 1985; Zachrisson and Mjor, 1975)
• IPR doesn’t cause mobility, tenderness to percus-
sion, thermal sensitivity, or negative electric pulp
testing results (Thordarson A, 1991).
• IPR with poor cooling might result in irreversible
pulpal damage (Zachrisson et al., 2011; Zachrisson
and Mjor, 1975)

Interproximal Enamel Reduction 107
Sarver, D.M., 2011a. Enameloplasty and esthetic finishing in
orthodontics-differential diagnosis of incisor proclination-the
importance of appropriate visualization and records part 2. Journal
of Esthetic & Restorative Dentistry: Official Publication of the
American Academy of Esthetic Dentistry 23, 303-313.
Sarver, D.M., 2011b. Enameloplasty and esthetic finishing in
orthodontics-identification and treatment of microesthetic features
in orthodontics part 1. Journal of Esthetic & Restorative Dentistry:
Official Publication of the American Academy of Esthetic Dentistry
23, 296-302.
Saver, D., 2004. Principles of cosmetic dentistry in orthodontis:
Part 1. Shape and proportionality of anteiror teeth. American jour-
nal of orthodontics and dentofacial orthopedics : official publica-
tion of the American Association of Orthodontists, its constituent
societies, and the American Board of Orthodontics 126, 749-753.
Sheridan, J.J., 1985. Air-rotor stripping. Journal of clinical ortho-
dontics : JCO 19, 43-59.
Thordarson A, Z.B., Mjor IA, 1991. Remodeling of canines to the
shape of lateral incisors by grinding: A long-term clinical and
radiographic evlauiation. Am. J. Orthod. Dentofacial Orthop. 100,
123-132.
Tuverson, D.L., 1980. Anterior interocclusal relations Part I. Am. J.
Orthod. 78, 361-370.
Zachrisson, B.U., Minster, L., Ogaard, B., Birkhed, D., 2011. Dental
health assessed after interproximal enamel reduction: caries risk in
posterior teeth. Am. J. Orthod. Dentofacial Orthop. 139, 90-98.
Zachrisson, B.U., Mjor, I.A., 1975. Remodeling of teeth by grind-
ing. Am J Orthod Dentofacial Orthop 68, 545-553.
Zachrisson, B.U., Nyoygaard, L., Mobarak, K., 2007. Dental health
assessed more than 10 years after interproximal enamel reduction
of mandibular anterior teeth. Am. J. Orthod. Dentofacial Orthop.
131, 162-169.
Zhong, M., Jost-Brinkmann, P.G., Zellmann, M., Zellmann, S.,
Radlanski, R.J., 2000. Clinical evaluation of a new technique for
interdental enamel reduction. J. Orofac. Orthop. 61, 432-439.

10
1. Aetiologies of Class I malocclusion
2. Extra-oral features of Class I malocclusion
3. Intra-oral features of Class I malocclusion
4. Methods of space provision to treat Class I mal-
occlusion
In this Chapter
CLASS 1 MALOCCLUSION
Written by: Mohammed Almuzian, Haris Khan, Zahid Majeed

Class 1 Malocclusion
110
The British Standard Incisor (BSI) classification is based on
the incisor relationship, while Angle’s classification is based
on the molar relationship. Class I incisor is defined as the in-
cisal edge of the lower incisors occludes or lies immediately
below the cingulum plateau of the upper incisors. (BSI, 1983).
Class I molar is defined as the mesiobuccal cusp of the up-
per first permanent molar occludes in the buccal groove of
the lower first permanent molar in terms of Angle’s classifica-
tion (also termed ‘neutrocclusion’) (Angle, 1899). Andrews’s
Class I molar relationship has two conditions: firstly, the
distal surface of the distal marginal ridge of the upper first
molar should contact and occlude with the mesial surface
of the mesial marginal ridge of the lower second molar (this
is originally from Stoller and was referred to as a Stollerized
molar) and secondly, the mesiobuccal cusp of the upper first
permanent molar should occlude in the buccal groove of the
lower first permanent molar.
A Class I malocclusion usually includes a Class I incisor and
molar relationship. Both molar and incisor relationships can
be affected by other dental features and may not be a true
reflection of the underlying skeletal relationship.
Class I malocclusion affects 60% of the Caucasian population
(Todd and Lader, 1991) and 80% of the Arab population (Al
Jadidi et al., 2018).
Aetiologies of Class I malocclusion
These include:
• Evolutionary factors mainly as a trend towards soft
diet leading to lack of attrition and subsequently
crowding.
• Genetic factors include impacted teeth, congeni-
tally missing teeth and microdontia (spacing).
• Environmental factors, including change in the
muscular balance or equilibrium on the developing
dentition, can lead to crowding and sucking habits
may lead to open bite, crossbite, increased vertical
dimensions etc. Another factor, trauma, may lead to
crowding due to a change in position of developing
tooth buds or tooth impaction and premature loss of
deciduous teeth.
Extra-oral features of Class I malocclusion
These include:
• Mostly, mesocephalic head shape.
• Skeletally Class I, however, mild Class II or Class III
skeletal bases may be seen.
• Straight profile.
• Average vertical proportions.
• Soft tissues are usually favourable (except bimaxil-
lary protrusion, where lip fullness and lips can be
incompetent).
Intra-oral features of Class I malocclusion
These include:
• The common intra-oral feature is crowding, but
spacing may also be seen.
• Incisors are in Class I relationship, canines and mo-
lars are usually in Class I relationship.
• Overjet is usually normal.
• Overbite can be increased, normal, or decreased
with an anterior open bite.
• The transverse relationship is usually normal, but a
crossbite may be present.
Methods of space provision to treat Class I malocclusion
The authors advocate the use of the acronym (SPEED TRIAL)
to memorise the methods of space provision;
• Stripping of the enamel (common).
• Proclination of the incisors (common).
• Extraction (common).
• Expansion (common).
• Distalization (mainly in the upper arch and ideally
prescribed before the eruption of the second mo-
lars).
• Torque, i.e. under torquing (applies for the upper
incisors only).
• Rotation correction (applies mainly for the premo-
lars and molars).
• Incremental growth (applies when the patient is
growing with an increased overjet). (With the man-
dible’s growth, the overjet decreases, which decreas-
es the space requirement for overjet correction.)
• Angulation, i.e. under tipping (mainly applied on
upper anterior and lower canine teeth).
• Leeway space (in the late mixed dentition).
Exam night review
• Angle’s Class I occlusion, Neutrocclusion, MB of
U6 occludes in BG of L6 (rotation, malposition,
crossbite etc.) (Angle, 1899)
• Andrews’s Class I molar if the distal surface of the
distal marginal ridge of U6→ the mesial marginal
ridge of L7 and the MB cusp of U6→ buccal groove
L6.
• Class I incisor relation: Incisor edge of LI occlude

Class 1 Malocclusion 111
or lie immediately below the cingulum plateau of UI
(BSI, 1983)
• Bimax-protrusion usually Class I malocclusion
• 60% of the Caucasian population and 80% in Arab
population (Todd and Lader, 1991)(Al Jadidi et al.,
2018)
• Methods of space provision include stripping of
the enamel, proclination of the incisors, extraction,
expansion, distalization, torque changes, rotation
correction, incremental growth, angulation changes
and utilising the Leeway space
• Extra-oral features: Mesencephalic, skeletal Class I
(mild skeletal Class II or III possible), straight pro-
file and average vertical lip fullness
• Intraoral features: Crowding/spacing, Class I inci-
sors, canines and molars, normal overjet and over-
bite, and variable transverse relationship.
• Aetiologies include evolutionary, genetic: and envi-
ronmental factors.
References
AL JADIDI, L., SABRISH, S., SHIVAMURTHY, P. G. & SENGUT-
TUVAN, V. 2018. The prevalence of malocclusion and orthodontic
treatment need in Omani adolescent population. J Orthod Sci, 7,
21.
ANGLE, E. H. 1899. Classification of malocclusion. Dental cosmos,
41, 248-264,350-357.
BSI 1983. British standard glossary of dental terms, British Stan-
dards Institution.
TODD, J. & LADER, D. 1991. Adult dental health, UK 1988. Office
of Population Censuses and Surveys. London: HMSO.

11
1. Aetiologies of bimaxillary proclination
2. Classification of bimaxillary proclination
3. Features of bimaxillary proclination
4. Treatment of bimaxillary proclination
5. Treatment considerations while managing bi
maxillary proclination
6. Relapse after treating bimaxillary dentoalveolar
proclination
7. Exam night review
In this Chapter
Bimaxillary
Proclination
Written by: Mohammed Almuzian, Haris Khan, Awrisha Tariq

Bimaxillary Proclination
114
Bimaxillary Proclination is defined as proclination of both
maxillary and mandibular arches or proclination of upper and
lower incisors that cause procumbent lips (Keating, 1986).
Controversy exists over the terminology of bimaxillary den-
toalveolar proclination; some researchers believed the term
should be used for prognathic maxillary and mandibular jaws
only. The term bimaxillary protrusion has been proposed for
prognathic jaws and bimaxillary dentoalveolar proclination
for proclined upper and lower teeth to differentiate between
jaws and incisors. Bimaxillary dentoalveolar proclination oc-
curs when both maxillary and mandibular incisors have been
proclined relative to dental and cranial bases resulting in pro-
cumbent soft tissue (Burden 1996).
Bimaxillary proclination mainly affects Afro-Caribbean’s
(Farrow et al., 1993). It is also common among Arab groups
and Asian (Hussein and Mois, 2007), but it is less prevalent in
white Caucasian populations (Keating, 1985).
Aetiologies of bimaxillary proclination
Bimaxillary dentoalveolar proclination is usually adapted to
underlying skeletal and soft tissue patterns. The main aetiolo-
gies are:
• Skeletal factors: It has mostly a genetic origin (Lam-
berton et al., 1980).
• Lip morphology/position (Naini and Gill, 2008):
In bimaxillary proclination, lips are often full and
everted. Tongue exerts pressure on the teeth so that
dental arches move forward as they grow. The effect
of soft tissues abnormality at rest is more than dur-
ing function.
• Nasal blockage (Solow and Tallgren, 1976b): Due
to nasal blockage, the patient becomes a mouth
breather, leading to bimaxillary dentoalveolar pro-
clination.
• Soft tissue stretching theory (Solow and Kreiborg,
1977, Solow and Tallgren, 1976b): This theory pro-
poses that airway obstruction leads to a neuromus-
cular feedback mechanism, where patients can’t
breathe through the nose due to nasal obstructions
or enlarged adenoids, so they adopt a ‘head-up pos-
ture’ with the extension of the neck. This leads to
stretching of suprahyoid muscles, skin and fascia.
This, in turn, imparts a force on the mandible leading
to a downward posture. The tongue, therefore, occu-
pies a lower position. There is less internal soft tissue
force on the maxillary arch (in the transverse plane).
The external force of the cheeks results in a narrower
maxillary arch, potentially causing a crossbite. At
the same time, the tongue is positioned forwards to
increase the pharyngeal space to aid breathing. The
forward position of the tongue imparts a greater in-
ternal force on the incisors, resulting in bimaxillary
dentoalveolar proclination.
• Dental factors (McCann and Burden, 1996): The
tooth size-arch length discrepancy can be expressed
in the form of proclination of incisors. Teeth with
a more forward path of eruption cause bimaxillary
dentoalveolar proclination.
• Habits: A tongue thrust habit can result in bimaxil-
lary dentoalveolar proclination in both endogenous
and adaptive forms.
• Pathological conditions include Cancrum oris, cere-
bral palsy, hemangioma and untreated cleft lip with
prognathic premaxilla.
Classification of bimaxillary proclination
Bimaxillary proclination is classified according to Interincisal
angle and include:
• Mild =125˚-115˚
• Moderate =115˚-105˚
• Severe =<105˚
However, the cephalometric values should be considered for
each race because bimaxillary proclination in one population
would be considered normal for other people.
Features of bimaxillary proclination
These include:
1. Skeletal features (Carter and Slattery, 1988, Keating, 1985)
such as:
• Prognathic maxillary and mandibular jaws
• Class I Malocclusion
• Mild class II malocclusion
• Short posterior cranial base
• Small posterior Facial height
• Divergent facial planes with steep mandibular plane
angle
• Increased FMPA
2. Dental features such as:
• There is dental proclination in both upper and lower
arches (Carter and Slattery, 1988). The lower incisor
proclination compensates for the ANB difference.
Due to the proclination of the incisor, the overbite
is mostly decreased, and, in some cases, the anterior
open bite may be present.
• Both dental arches are larger in length due to the
proclination of teeth resulting in spacing and dia-
stema.

Bimaxillary Proclination 115
• The overjet may be normal or increased.
• Molar relations are usually class I.
• The size of teeth is usually large as compared to av-
erage population (McCann and Burden, 1996). As
bimaxillary proclination is more common in Afro-
Caribbeans’ study, (Keene, 1979) reported that
tooth size for the overall maxillary and mandibular
dentition among black people was on average 8.4%
larger than for whites.
3. Soft tissue features (In Africa-Caribbean)(Connor and
Moshiri, 1985): typically, patients present with:
• Convex facial form
• Increased lip length
• Everted lips In black females, lips are more protrud-
ed than in white females (Fonseca and Klein, 1978).
• Incompetent lips
• Long and thick tongue (Adesina et al., 2013)
• Low lower lip line, high upper lip line (Keating,
1985)
• Receded chin
• Holdaway angle increased with prominent lips
• Acute nasolabial angle and labiomental angle
Treatment of bimaxillary proclination
The main treatment objectives are (Carter and Slattery, 1988):
• Improve aesthetics, i.e. flatten profile.
• Improve lip competency.
• Alignment and levelling.
• Correction of incisor relationship.
• Maintenance of a stable result.
Treatment considerations while managing bimaxillary
proclination
These include:
• Mild bimaxillary dentoalveolar proclination: In
growing patients, no treatment is required as protru-
sion can be masked by the forward and downward
movement of the nose and the ageing effect. In a
mild case, interproximal reduction (IPR) can also be
performed to provide space for incisor retraction.
• Moderate bimaxillary dentoalveolar proclination:
First, premolar extractions are the treatment of
choice if the molar relation is Class I to reduce soft
tissue procumbence (Bills et al., 2005). Upper arch
extractions may be indicated if the molar relation-
ship is class II with no lower crowding. IPR in the
lower arch combined with upper extractions or IPR
in both arches can be performed to provide space. If
enmasse retraction is desired, TADs provide better
anchorage than conventional anchorage. TADs can
also decrease vertical proportions due to an intru-
sive effect depending on the direction and level of
force application (Upadhyay et al., 2008).
• Severe cases: Orthognathic surgery is proposed to
correct significant skeletal problems using a subapi-
cal osteotomy with or without genioplasty. In cases
of AOB, surgical maxillary posterior impaction and
clockwise rotation of the occlusal plane is the treat-
ment of choice (Chu et al., 2009). Anterior segmen-
tal osteotomy can be used if the overjet is increased.
This type of surgery can also be helpful if the patient
has a gummy smile and underdeveloped chin posi-
tion (Lee et al., 2007).
Relapse after treating bimaxillary dentoalveolar proclina-
tion
Teeth remain in an equilibrium between external forces ex-
erted by lips and cheek and internal forces of the tongue. If
the equilibrium is changed due to tooth movement, there are
greater chances of relapse, as the forces seek to move the teeth
back to the equilibrium position. In bimaxillary dentoalveo-
lar proclination cases, stability depends upon lip and tongue
adaptation to incisor retraction. Ideally, the interincisal angle
is normalised with good buccal interdigitation. 20% of the
treated bimaxillary dentoalveolar proclination Class I cases
had a relapse of the inter-incisal angle, while Class II cases
showed a 30% relapse (Keating, 1986). VFR supporting per-
manent fixed retainers are advised. Upper incisors should be
covered by one-third of the lower lip.
Exam night review
• Proclination of maxillary & mandibular arches or
a condition in which upper and lower incisors are
proclined →procumbent lips
• Most common Afro-Caribbean’s (Farrow et al.,
1993)
• Less prevalent in white Caucasian (Keating, 1985).
Aetiology
• Skeletal factors.
• Lip morphology/position (Naini and Gill, 2008).
• Nasal blockage (Solow and Tallgren, 1976a).
• Soft tissues stretching theory (Solow and Kreiborg,
1977, Solow and Tallgren, 1976b).
• Enlarged adenoids.

Bimaxillary Proclination
116
• Endogenous (primary) thrust.
• Dental factors.
• Habits.
• Pathological conditions.
Classification
• Mild =125˚-115˚.
• Moderate =115˚-105˚.
• Severe = <105˚.
Skeletal features
• Prognathic maxillary and mandibular jaws.
• Divergent facial planes with steep mandibular plane
angle.
Dental features
• Dental bimaxillary dentoalveolar proclination,
IIA.
• Proclined LLS.
• overbite & openbite tendency.
• Larger dental arches with spacing.
• Normal overjet.
• Molar relations usually Class I.
Soft tissue features
• Convex facial form.
• Lip incompetency.
• Acute LNA and LMA.
• Everted lips in black females.
Management
Mild bimaxillary dentoalveolar proclination cases
• In growing patients --no treatment.
• In mild cases (IPR).
Moderate bimaxillary dentoalveolar proclination cases
• First premolar extraction → treatment of choice
• If molar relation Class II treat with extraction of up-
per molars.
• Avoid Class II elastics → extrusive effect (Koyama
et al., 2010)
Severe cases
• Orthognathic surgery for severe skeletal problems.
• AOB, max post intrusion/surgical impaction →rota-
tion of occlusal plane is treatment of choice (Chu et
al., 2009)
• Anterior segmental osteotomy for overjet, gummy
smile & underdeveloped chin (Lee et al., 2007)
Relapse
• Stability depends upon lip adaptation to incisor re-
traction.
• IIA is normalized with good buccal interdigitation.
• VFR supporting permanent fixed retainer.
• Long term stability is unpredictable.
• UI covered 1/3rd lower lips.

Bimaxillary Proclination 117
References:
ADESINA, B. A., OTUYEMI, O. D., KOLAWOLE, K. A. & AD-
EYEMI, A. T. 2013. Assessment of the impact of tongue size in
patients with bimaxillary protrusion. International orthodontics,
11, 221-232.
CARTER, N. & SLATTERY, D. 1988. Bimaxillary proclination in
patients of Afro-Caribbean origin. British journal of orthodontics,
15, 175-184.
CHU, Y.-M., BERGERON, L. & CHEN, Y.-R. Bimaxillary protru-
sion: an overview of the surgical-orthodontic treatment. Seminars
in plastic surgery, 2009. © Thieme Medical Publishers, 032-039.
CONNOR, A. M. & MOSHIRI, F. 1985. Orthognathic surgery
norms for American black patients. American journal of orthodon-
tics, 87, 119-134.
FARROW, A. L., ZARRINNIA, K. & AZIZI, K. 1993. Bimaxillary
protrusion in black Americans—an esthetic evaluation and the
treatment considerations. American journal of orthodontics and
FONSECA, R. J. & KLEIN, W. D. 1978. A cephalometric evaluation
of American Negro women. American journal of orthodontics, 73,
152-160.
GERMEÇ, D. & TANER, T. U. 2008. Effects of extraction and
nonextraction therapy with air-rotor stripping on facial esthetics in
postadolescent borderline patients. American Journal of Ortho-
dontics and Dentofacial Orthopedics, 133, 539-549.
HUSSEIN, E. & MOIS, M. A. 2007. Bimaxillary protrusion in the
Palestinian population. The Angle orthodontist, 77, 817-820.
JACOBS, J. D. & BELL, W. H. 1983. Combined surgical and orth-
odontic treatment of bimaxillary protrusion. American journal of
orthodontics, 83, 321-333.
KEATING, P. 1985. Bimaxillary protrusion in the Caucasian: a
cephalometric study of the morphological features. British journal
of orthodontics, 12, 193-201.
KEATING, P. 1986. The treatment of bimaxillary protrusion: a
cephalometric consideration of changes in the inter-incisal angle
and soft tissue profile. British journal of orthodontics, 13, 209-220.
KEENE, H. J. 1979. Mesiodistal crown diameters of permanent
teeth in male American Negroes. Am J Orthod, 76, 95-9.
KOYAMA, I., IINO, S., ABE, Y., TAKANO-YAMAMOTO, T. &
MIYAWAKI, S. 2010. Differences between sliding mechanics with
implant anchorage and straight-pull headgear and intermaxillary
elastics in adults with bimaxillary protrusion. The European Jour-
nal of Orthodontics, 33, 126-131.
LAMBERTON, C. M., REICHART, P. A. & TRIRATANANIMIT, P.
1980. Bimaxillary protrusion as a pathologic problem in the Thai.
LEE, J. K., CHUNG, K. R. & BAEK, S. H. 2007. Treatment out-
comes of orthodontic treatment, corticotomy-assisted orthodontic
treatment, and anterior segmental osteotomy for bimaxillary den-
toalveolar protrusion. Plast Reconstr Surg, 120, 1027-36.
MCCANN, J. & BURDEN, D. J. 1996. An investigation of tooth size
in Northern lrish people with bimaxillary dental protrusion. The
NAINI, F. B. & GILL, D. S. 2008. Facial aesthetics: 2. Clinical as-
sessment. Dental update, 35, 159-170.
SOLOW, B. & KREIBORG, S. 1977. Soft-tissue stretching: a pos-
sible control factor in craniofacial morphogenesis. Scand J Dent
Res, 85, 505-7.
SOLOW, B. & TALLGREN, A. 1976a. Head posture and craniofa-
cial morphology. American Journal of Physical Anthropology, 44,
417-435.
SOLOW, B. & TALLGREN, A. 1976b. Head posture and craniofa-
cial morphology. Am J Phys Anthropol, 44, 417-35.
UPADHYAY, M., YADAV, S., NAGARAJ, K. & PATIL, S. 2008.
Treatment effects of mini-implants for en-masse retraction of an-
terior teeth in bialveolar dental protrusion patients: a randomized
controlled trial. American Journal of Orthodontics and Dentofacial
Orthopedics, 134, 18-29. e1.

12
1. Incidence of Class II Division 1 malocclusion
2. Aetiology of Class II Division 1 malocclusion
3. Features of Class II Division 1 malocclusion
4. Type of lip behaviour
5. Justifications for early treatment of Class II mal
occlusions
6. Treatment timing for Class II Division 1 maloc
clusion
7. Class II growth modification / functional jaw
orthopaedics
8. Effects of Class II functional appliances
9. The proposed advantages of the phase I inter
vention
10. Effectiveness of phase I intervention
11. Orthodontics camouflage to treat Class II Divis
ion 1 malocclusion
12. Favourable features for orthodontics camouflage
13. Combined orthodontic-surgical approach
14. Indicators for orthognathic surgery
15. Aetiology of relapse
16. Enhancing the stability of treated Class II Divi
sion 1 malocclusions
In this Chapter
Class II Division 1
Malocclusion
Written by: Mohammed Almuzian, Haris Khan, Zahid Majeed

Class II Division 1 Malocclusion
120
Class II incisor relationship describes a situation where the
incisal edges of the mandibular incisors lie posterior to the
cingulum plateau of the maxillary incisors, the upper inci-
sors are either proclined or have a normal inclination, and the
overjet is increased (BSI, 1983).
Class II molars relationship describes a situation where the
mesiobuccal cusp of the permanent maxillary first molar lies
mesial to the buccal groove of the permanent first mandibu-
lar molar. Class II intermediate is defined as a Class II incisor
relationship with an increased overjet (5-7mm) with upright
upper incisors. In contrast, Class II indefinite is defined as
one upper central incisor proclined and one retroclined. The
cephalometric definition of Class II is when the ANB angle is
greater than 4° for the Caucasian population.
Incidence of Class II Division 1 malocclusion
The incidence of Class II Division 1 is 20% (Todd and Lader, 1991),
representing the most prevalent malocclusion in Caucasian popu-
lations (Foster and Walpole Day, 1974, Helm, 1968, Proffit et al.,
1998). The prevalence of Class II intermediate is 10% (Williams
and Stephens, 1992), while Class II indefinite is found in 9 % of the
population. (which population)
Aetiology of Class II Division 1 malocclusion
These include:
1. Skeletal factors such as:
• The effect of teratogens on mandibular growth.
• Fetal moulding, suppressing the growth of the man-
dible
• Trauma to the TMJ during the birthing process;
childhood fractures of the jaw; or arthritic problems.
2. Dental factors such as:
• Macrodontia of the upper teeth or microdontia of
the lower teeth
• Crowding in the upper arch.
• Supernumerary teeth in the upper arch or hypodon-
tia in the lower arch.
• Pathological forward migration of teeth.
3. Soft tissue factors such as:
• Lip incompetence, short upper lip leading to flared
upper incisors.
• Lower lip trap.
• Hypotonic upper lip.
• Lower lip to palate swallowing
4. Habits such as:
• Digit sucking.
• Mouth breathing.
• Tongue thrusting
Features of Class II Division 1 malocclusion
These include:
1. Skeletal Features (Hopkins et al., 1968): A Class II malocclusion
is common on a skeletal Class II base (76% of the cases have skeletal
class 2 bases). However, they can be found on a skeletal Class I base
and rarely on a skeletal Class III base. A skeletal Class II relationship
is mainly due to mandibular retrognathia (75%) and less commonly
due to a prognathic maxilla (25%). Retro-positioning of the man-
dible can be due to an increase in the cranial base angle. However,
an increase in the cranial base length leads to a prognathic maxilla.
If a Class II malocclusion exists on a skeletal Class I base, the incisor
relationship may be due to the soft tissue or environmental factors,
for example, digit sucking or a lower lip trap.
2. Dental Features such as:
• Increased overjet.
• Spacing of the upper incisors.
• Lower incisors are crowded or proclined depending
upon the lower lip trap.
• Deep bite, or an open bite.
• An open bite may exist due to an adaptive swallow-
ing pattern, secondary to increased overjet,
• A Class II subdivision malocclusion exhibits an
asymmetry in the buccal segments; one side is Class
II, and the other is Class I.
• Posterior crossbites may be present due to antero-
posterior discrepancy in jaw position secondary to
habits.
• Deep curve of Spee due to supra-eruption of inci-
sors.
3. Cephalometric features such as:
• Increased cranial base angle.
• Increased ANB angle.
• Morphologically, short or retrognathic mandible.
• Prognathic maxilla.
• Variable maxillary-mandibular plane angle (in-
creased or reduced).
• Variable gonial angle (increased or reduced).
• Variable lower facial height (increased or reduced).
• Decreased inter-incisal angle.
4. Soft tissue features such as:
• Convex profile and soft tissues may be retrusive to

Class II Division 1 Malocclusion 121
Rickett’s E line.
• Reduced nasolabial angle.
• Incompetent, potentially competent lips.
• Lower lip trapping.
• Hypotonic upper lip.
• The lower lip is not covering the upper incisors.
• Retruded chin.
Type of lip behaviour to achieve anterior oral seal in pa-
tients with Class II malocclusion
These include:
• Lower lip to the palate: The lower lip rests palatal
to the maxillary incisors. This is associated with ret-
roclined lower incisors and/or proclined upper inci-
sors.
• Lower lip to tongue: The tongue is pushed forward
to contact the lower lip, resulting in an incomplete
deep bite. The mandibular incisors are often pro-
clined. This forward posture of the tongue can be
described as an adaptive tongue thrust.
• Forward posturing of the mandible: It allows the
lips to meet together. In this scenario, the soft tissues
promote dentoalveolar compensation, decreasing
the effect of the skeletal Class II pattern. This habit-
ual forward posturing of the mandible is also known
as a ‘Sunday bite’.
Justifications for early treatment of Class II malocclusions
These include:
• Trauma (Todd and Dodd, 1985): The risk of trauma
when the overjet is greater than 9mm in 12yr old is
around 45% (Batista et al., 2018), early intervention
results in a small decrease in this risk.
• Self-esteem (O’Brien et al., 2003b): Early overjet re-
duction may help to improve a patient’s self-concept
scores.
• Bullying (Seehra et al., 2011): 12.8% of patients re-
ferred for treatment are bullied, particularly those
with an increased overjet.
• To eliminate a traumatic bite by the lower incisors.
Treatment timing for Class II Division 1 malocclusion
Treatment can be performed during:
Primary dentition: Treatment during primary dentition is no longer
indicated.
Mixed dentition: Growth modification can start 1-3 years before the
peak adolescent growth spurt. However, transitioning to permanent
dentition can be clinically challenging to manage.
Permanent dentition: Treatment options in permanent dentition
are:
• Growth modification,
• Orthodontic camouflage.
• Combined orthodontics and surgical approach.
Growth modification / functional jaw orthopaedics to treat
Class II Division 1 malocclusion
Growth modification appliances are used to alter/ remove the re-
strictive effects of masticatory and facial muscles, therefore, chang-
ing the skeletal, soft tissue and dental relationships. Growth modi-
fication appliances maximise the patient’s potential growth. Growth
modification is usually used as phase 1 intervention (early treat-
ment) during the mixed dentition or as phase 2 definitive treat-
ment (delayed treatment) with/without fixed appliances during
the permanent dentition (Taffarel et al., 2018). The post-functional
fixed appliance phase aims to improve finishing and detailing of the
occlusion, retain the corrected overjet, tip/torque of incisors, and
achieve Class I with the condyle centred in the fossa.
Effects of Class II functional appliances
These include:
• They enhance mandibular growth with increased
condylar height and length and remodelling in the
glenoid fossae. However, these changes cannot be
more than what is genetically predetermined.
• Restriction of maxillary skeletal growth (headgear
effect).
• Increased pterygoid muscle activity followed by
adaptive condylar growth during treatment (1-
3mm).
• Distal tipping of upper posterior teeth.
• Retroclination of the upper anterior teeth.
• Mesialization of the lower posterior teeth.
• Proclination of the lower incisors.
• Differential upward and forward eruption of the
lower buccal segments results in a clockwise rotation
of the occlusal plane and increased facial height.
• Expansion of the maxillary buccal segments if an ex-
pansion screw is incorporated.
The proposed advantages of the phase I intervention
These include:
• Reduction in the incidence of incisor trauma
(O’Brien et al., 2003a).
• Improvements in self-esteem and increase in self-
concept (O’Brien et al., 2003a).
• Improves skeletal pattern.

122
• Reduces the length of subsequent phase 2 treatment
(usually fixed appliances).
• Reduces the need for extractions in phase 2 treat-
ment.
• Relief of gingival trauma.
• Changes are more likely in early treatment as cra-
niofacial tissues are more malleable at a younger age.
Disadvantages of phase I intervention
These include:
• Patient compliance might be burnt due to the in-
creased duration of the overall treatment.
• Soft tissues do not mature until 15 years of age.
Therefore, the lag in vertical lip growth may com-
promise the stability of the corrected overjet.
Effectiveness of phase I intervention (Thiruvenkatachari
et al., 2015, Batista et al., 2018)
According to a Cochrane review (Batista et al., 2018), 2 stage treat-
ment (i.e. early treatment followed by fixed appliances in the per-
manent dentition) is not particularly advantageous over 1 stage of
treatment in adolescence (i.e. functional appliance treatment fol-
lowed by fixed appliances consecutively), except for a reduction in
the incidence of incisal trauma. Trauma is the strongest indication
for early treatment, though the risk, benefit, efficacy and cost could
not be established (King et al., 1990).
Another study suggests that incisor injuries tend to be minor, so
incisor trauma treatment is minimal compared with the cost of 2
phase orthodontic treatment (Koroluk et al., 2003).
Orthodontics camouflage to treat Class II Division 1 mal-
occlusion
Objectives of orthodontic camouflage of Class II Division 1 maloc-
clusion are:
• Relief of crowding.
• Level and align the arches.
• Normalise the overjet and overbite.
• Correction of buccal segment relationship.
• Midline correction.
• Lower lip resting over upper incisors.
Orthodontics camouflage treatment modalities to treat
Class II Division 1 malocclusion
These include:
• An upper removable appliance (URA) can be used
when simple tipping of upper incisors is required.
• Distalization of the upper arch might be prescribed
to provide space for overjet correction and relieve
crowding.
• Space can also be provided through extraction. In
the long-term, the post-treatment stability regard-
ing overjet, overbite, canine and molar relationships
have similar results in extraction and non-extraction
Class II malocclusion cases (Janson et al., 2012).
Similarly, correction of Class II malocclusions either
with the extraction of 2 maxillary units or extrac-
tion of 4 units (2 lower extractions as well ) results
in a similar long-term stability (Janson et al., 2009).
However, proper inter-cuspal interdigitation after
debonding is essential in enhancing the achieved
occlusion (Chhibber et al., 2010).
Favourable features for orthodontics camouflage
These include:
1. Intervention during active growth is considered favour-
able due to potential mandibular growth (mandibular growth
follows a similar pattern to somatic growth).
2. Favourable skeletal features such as:
• Class I or mild Class II skeletal base relationship.
• Average or reduced lower face height.
• Mild transverse discrepancies.
3. Favourable dental features (Burden et al., 1999) such as:
• Overjet of less than 9mm, favourably if combined
with proclined upper incisors.
• Average or slightly increased overbite.
• Mild to moderate crowding.
• The molar relationship is less than 3/4 unit Class II.
Combined orthodontic-surgical approach
The routine surgical procedure for treating a moderate to se-
vere Class II dentoskeletal deformity is a bilateral sagittal split
ramus osteotomy (BSSO) to advance the mandible. Alterna-
tively, a vertical sub-sigmoid osteotomy or total mandibular
subapical alveolar osteotomy can be prescribed in some cases
(Pangrazio-Kulbersh et al., 2001).
Indicators for orthognathic surgery
These include:
• Adult/non-growing patients.
• If orthodontic treatment alone can cause detrimen-
tal effects on the facial aesthetics and oral tissues.
However, borderline cases have shown to be pleas-
ing in both surgical and non-surgical cases (Mihalik
et al., 2003)).
• Severe skeletal discrepancy cannot be corrected by
orthodontics alone. Theoretically, this can be deter-
mined using different yardsticks. For example, Prof-

fit (Proffit et al., 1992) suggested that surgical inter-
vention is indicated if the overjet of 10mm or more,
the Pog to Nasion perpendicular is 18mm or more,
the mandibular corpus length is less than 70 mm and
facial height more than 125mm. Squire (Squire et al.,
2006) stated that surgical intervention is advisable
if the transverse discrepancy is greater than 3mm,
which is not considered amenable to orthodontic
treatment alone and ANB greater than 9° combined
with severe vertical or transverse discrepancy with
decreased incisor show on a smile.
Aetiology of relapse of the treated Class II Division 1 mal-
occlusion
These include:
• Biological factors: Lack of gingival and periodontal
remodelling.
• Iatrogenic factors: Movement of teeth out of soft tis-
sue equilibrium.
• Growth factors: Differential growth factors that pre-
dispose to relapse.
• Environmental factors: continued parafunctional
habits.
• Idiopathic causes: Idiopathic condylar resorption
(ICR).
• Lack of lower lip coverage on upper incisors
• Any combination of the above.
Enhancing the stability of treated Class II Division 1 mal-
occlusions
These include:
• Overcorrection.
• Long term permanent retainers.
• Continuation of headgear/functional appliances
part-time, for example, at night until growth has
ceased.
• Discontinuation of habits.
• Occlusal interdigitation is an essential factor in the
stability of the achieved corrections.
• If lower incisors are being moved by more than
2mm, they should be retained permanently.
• In case of upper incisor retraction, they should be
retracted within the control of the lower lip.
• Correct lower incisor edge centroid relationship.
• Minimise posterior teeth extrusion in adult patients.
Exam night review
• Incisal edges of LI posterior to the cingulum plateau
of UI while UIs are either proclined or normal incli-
nation. Overjet is increased (BSI 1983).
• Class II intermediate similar Class II/1 with overjet
(5-7mm) but UI upright/slightly retroclined.
• Class II/1 with one upper central incisor proclined
& one retroclined called Class 2II indefinite.
Incidence
• 20% (Todd and Lader, 1991) most prevalent mal-
occlusion in Caucasians (Foster and Walpole Day,
1974, Helm, 1968, Proffit et al., 1998).
• Class II intermediate 10% (Williams and Stephens,
1992), class 2 indefinite 9 %.
Aetiology
• Dental factors.
• Soft tissue influences.
• Habits.
Justifications for the early treatment class 2 malocclusion
• Reduce the risk of trauma: Risk of trauma when
overjet greater than 9mm in 12yr old is around 45%
(Batista et al., 2018).
• Improve self-esteem (O’Brien et al., 2003b).
• Reduce the risk of bullying (Seehra et al., 2011).
• Eliminate traumatic bite by lower incisors.
The claimed reasons/advantages for early treatment in mixed
dentition phase (O’Brien et al., 2003a)
• Reduction in the incidence of incisor trauma,
• Improvements in self-esteem and increase in self-
concept,
• Improves skeletal pattern,
• Reduces the length of subsequent phase 2 treatment.
• Reduces the need for extractions in phase 2 treat-
ment.
• Relief of gingival trauma.
• Treatment is easy in that stage as craniofacial tissues
are more malleable.
Favourable features for orthodontics camouflage
1. Growth features: Mandibular growth follows a
somatic growth pattern. Growth ceased in adults.

124
2. Skeletal features:
• Class I or mild Class II skeletal base relationship.
• Average or reduced lower face height.
• Very mild transverse discrepancies.
Dental features (Burden et al., 1999):
• Favourable if overjet is less than 9mm and com-
bined with proclined incisors.
• Average or slight increased overbite.
• Mild to moderate crowding.
• Molar relationship is less than 3/4 unit Class II.
Indicators for orthognathic surgery
• Adult/non-growing patients.
• Severe skeletal discrepancy.
• Overjet 10mm or more.
• Pog to Nasion perpendicular is 18mm or more.
• Mandibular corpus length is less than 70 mm.
• Facial height more than 125mm.
• Transverse discrepancies greater than 3mm were
not considered orthodontically treatable.
• ANB is greater than 9°.
• Severe vertical or transverse discrepancy.
• Severe deep bite with decreased incisor show on a
smile.
Aetiologies of relapse of treated Class II Division 1 malocclu-
sion
• Biological factors: Lack of gingival and periodontal
remodelling,
• Iatrogenic factors: Movement of teeth out of equilib-
rium of soft tissue
• Growth factors: Differential growth factor which
predisposes to relapse.
• Environmental factors: continued parafunctional
habits,
• Idiopathic causes: Idiopathic condylar resorption
(ICR), OR
• Any combination of the above.
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BURDEN, D. J., MCGUINNESS, N., STEVENSON, M. & MC-
NAMARA, T. 1999. Predictors of outcome among patients with
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the permanent dentition. American journal of orthodontics and
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N., CHADWICK, S., CONNOLLY, I., COOK, P., BIRNIE, D.,
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PANGRAZIO-KULBERSH, V., BERGER, J. L., KACZYNSKI, R. &
SHUNOCK, M. 2001. Stability of skeletal Class II correction with 2
surgical techniques: the sagittal split ramus osteotomy and the total
mandibular subapical alveolar osteotomy. American Journal of
PROFFIT, W., FIELDS, J. H. & MORAY, L. 1998. Prevalence of
malocclusion and orthodontic treatment need in the United States:
estimates from the NHANES III survey. The International journal
of adult orthodontics and orthognathic surgery, 13, 97-106.
PROFFIT, W. R., PHILLIPS, C., TULLOCH, J. F. & MEDLAND,
P. H. 1992. Surgical versus orthodontic correction of skeletal Class
II malocclusion in adolescents: effects and indications. Int J Adult
Orthodon Orthognath Surg, 7, 209-20.
SEEHRA, J., FLEMING, P. S., NEWTON, T. & DIBIASE, A. T.
2011. Bullying in orthodontic patients and its relationship to mal-
occlusion, self-esteem and oral health-related quality of life. Journal
SQUIRE, D., BEST, A. M., LINDAUER, S. J. & LASKIN, D. M.
2006. Determining the limits of orthodontic treatment of overbite,
overjet, and transverse discrepancy: a pilot study. Am J Orthod
TAFFAREL, I. P., SAGA, A. Y., LOCKS, L. L., RIBEIRO, G. L. &
TANAKA, O. M. 2018. Clinical Outcome of an Impacted Maxillary
Canine: From Exposition to Occlusion. J Contemp Dent Pract, 19,
1552-1557.
THIRUVENKATACHARI, B., HARRISON, J., WORTHINGTON,
H. & O’BRIEN, K. 2015. Early orthodontic treatment for Class II
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148, 47-59.
TODD, J. E. & DODD, T. 1985. Children’s Dental Health in the
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incisor classification of malocclusion. Br J Orthod, 19, 127-30.

13
1. Classification of Class II Division 2 malocclusion
2. Incidence of Class II Division 2 malocclusion
3. Aetiology of Class II Division 2 malocclusion
4. Features of Class II Division 2 incisor relation
ships
5. Justification for treatment
6. Treatment aims
7. Treatment considerations
8. Treatment option
9. Timing of treatment
10. Stability and retention
11. Proclination of lower incisors in Class II Divi
sion 2 cases
In this Chapter
Class II Division 2
malocclusion

128
Class II Incisor relationship: The lower incisor edge oc-
cludes palatal to the cingulum plateau of the upper central
incisor, with retroclined upper incisors and the overjet usu-
ally being minimal or possibly increased (BSI, 1983). If the
overjet is in the range of 5-7 mm and incisors are retroclined,
it is known as Class II intermediate (Williams, 1992)
Classification of Class II Division 2 malocclusion
Van der Linden’s sub-classification of Class II Division 2 is
based on the position of the upper incisors and canines rela-
tive to each other (Van der Linden, 1983).
• Type A: The upper central and lateral incisors are
retroclined, with no overlapping by canines. It is less
severe in nature.
• Type B: The central incisors are retroclined and
overlapped by the lateral incisors.
• Type C: The central and lateral incisors are retro-
clined and overlapped by the canines.
• Type D: A combination of the above subtypes.
Incidence of Class II Division 2 malocclusion
Class II Division 2 is a relatively uncommon malocclusion,
representing 2.3-5% of all malocclusions of the Western Cau-
casian population (Ast et al., 1965)(Mills, 1966). The preva-
lence in children in the United Kingdom is 10% (Millett et al.,
2012, Foster and Day, 1974).
Aetiology of Class II Division 2 malocclusion
Class II Division 2 is a combination of environmental and
genetic factors.
1. Genetic and familial origin: The evidence that Class II
Division 2 could have a genetic component are:
• The study of 20 monozygotic twins showed that
all twins had a Class II Division 2 incisor relation-
ship, while only 10.7% of 28 dizygotic twins had a
Class II Division 2 incisor relationship (Markovic,
1992). The high concordance in monozygotic twins
and much lower concordance for dizygotic twins
suggests that Class II Division 2 have an autosomal
dominant inheritance pattern, with more than one
genetic factor contributing to this malocclusion.
• Tooth agenesis, excluding third molars, was at least
three times more common in Class II Division 2
subjects than in the general population (Basdra et
al., 2000).
• Reduced width of lateral incisors had a greater prev-
alence in Class II Division 2 incisor relationships
(Peck et al., 1998).
• An increased prevalence of impacted maxillary ca-
nines among Class II Division 2 subjects (Basdra et
al., 2000).
2. Environmental factors such as:
• Soft tissue factors: A high resting position of the
lower lip over the upper incisors results in increased
resting pressure, approximately 2.5 times greater
than upper lip resting pressure, which is linked with
retroclination of the maxillary incisors (Lapatki et
al., 2002). Hyperactive or hypertonic lips or a ‘strap-
like lower lip’ have been implicated in the Class II
Division 2 (Karlsen, 1994).
• Dental factors such as overeruption of the incisors,
long central and short lateral incisors, which results
in the lateral incisors ‘escaping’ from the effects of
the lower lip force, increased crown root angle of the
upper incisor, known as the Collum angle (McIntyre
and Millett, 2003), and thin incisors with small cin-
gulum.
• Skeletal factors due to increased cranial base length
and angle (Hopkins et al., 1968) or reduced lower
facial height (Pancherz et al., 1997).
• Growth factors due to overdevelopment of the up-
per anterior alveolar process or forward rotation of
the mandible result in the lower lip moving superi-
orly in position.
Features of Class II Division 2 incisor relationships
1. Skeletal features such as
• Usually mild Class II skeletal base but can be I or III.
• Increased cranial base angle leading to mandibular
retrognathia (Hopkin et al., 1968).
• Longer cranial base leading to the prognathic max-
illa.
• Decreased lower face height, gonial angle, mandib-
ular plane angle and skeletal deep bite (Al-Khateeb
and Al-Khateeb, 2009).
• Maxilla may be short, broad and forward relative to
the mandible leading to a tendency for a scissor bite.
2. Soft tissue features such as
• High resting lower lip line due to decreased lower
face height.
• Typically strap-like lower lip (increase in muscular
tone).
• Marked labio-mental fold, and
• High masseteric muscle forces due to hypertrophic
muscle (Ingervall and Thilander, 1974,Sciote et al.,
2012).

• Increased inter-incisal angle,
• Pronounced retroclination of the upper central inci-
sors (Brezniak et al., 2002).
• Retroclined upper and lower incisors.
• Upper laterals are often proclined, mesially tipped
and mesiolabially rotated (lower lip fails to cover
shorter crown).
• Deep bite (Brezniak et al., 2002) with reduced over-
jet and extruded upper incisors.
• Buccal segments are Class II,
• Scissor bite is common in the premolar region due
to the transverse discrepancy.
• Upper central incisors demonstrate increased
crown-root angles (Collum angle) which indicates
an excessive palatal “bend” of the crown (Feres et al.,
2018).
• Incisors may be thin with a poorly defined cingulum
(Robertson and Hilton, 1965).
Justification for treatment
These include:
• Aesthetics improvement.
• To eliminate traumatic bite that is potentially result-
ing in stripping of upper palatal gingiva due to trau-
matic occlusion with the palate and/ or recession of
lower labial mucosa, due to upper incisors imping-
ing on the gums of the lower labial segment from the
labial aspect, or
• To improve tooth alignment, in particular the upper
lateral incisors.
Treatment aims
These include:
• Relieve of crowding.
• Level and align the arches.
• Correction of overbite and traumatic bite.
• Correct lower incisor edge-centroid relationship
(lower incisor edge should lie anterior to the upper
root centroid) (Houston, 1989).
• Normalisation of interincisal angle, often requiring
intrusion and palatal root torquing of upper incisors
(Mills, 1973).
• Correct buccal segment relationships.
Treatment considerations
These include:
• Crown-root angle (Collum angle): A large angle has
been suggested as the possible reason for the deep
overbites generally observed in Class II Division 2
incisor cases. Increased crown-root angle can in-
crease an individual’s risk for root resorption when
intruding, extruding and torquing teeth.
• Bracket prescription: A high torque option is pre-
ferred for the upper central incisors due to the de-
gree of retroclination of the upper incisors.
Treatment options
These include:
• No treatment.
• Orthognathic surgery: When the skeletal discrepan-
cy is severe, i.e. ANB>9° in a non-growing patient,
orthodontics combined with orthognathic surgery is
the preferred option.
• Orthodontic camouflage: Orthodontic treatment
of a Class II Division 2 malocclusion is known to
be difficult and prone to relapse (Canut and Arias,
1999). The following appliances can be used:
1. Upper removable appliance (URA): URA is usually com-
bined with low pull headgear (supported by molar bands)
and/ or anterior bite plane to limit incisor eruption and al-
low lower molars to erupt. The expansion and labial segment
alignment appliance (ELSSA) is used primarily to align and
procline the upper labial segment in Class II cases before
functional appliance therapy (Dyer et al., 2001).
2. Functional appliances: A modified twin block with an
anterior screw, double cantilever spring, Z or double springs
to procline the maxillary incisors and to correct the sagittal
relationship with same appliances has been suggested (Dyer
et al., 2001).
3. Fixed appliances: Fixed appliances are required when
bodily tooth movement is needed or there is a need to torque
upper incisors. Avoid extractions in low-angle cases is gen-
erally recommended as space closure can be challenging
(Bjork and Skieller, 1972). If extraction is inevitable to relieve
crowding, preference is given to second premolar extraction
rather than first premolars to minimise retroclination of the
lower labial segment.
Timing of treatment
These include:
• According to a Cochrane review, there is no evi-
dence from clinical trials to advocate one appliance
type over another in managing Class II Division 2
malocclusion in the children (Millett et al., 2018).
• Treatment can be commenced during the mixed

130
dentition to prevent deepening of the overbite using
a removable appliance. Treatment in the permanent
dentition usually involves growth modification, dis-
talization and less commonly, extractions.
Stability and retention
Poor quality evidence exists about management and stabil-
ity of Class II Division 2 malocclusion (Millett et al., 2012).
Guidelines are proposed based on current evidence:
• Treat in a timely manner to address overbite,
• Treat preferably non-extraction, and
• Correct edge to centroid relation and interincisal
angle, and move upper incisors away from lower lip.
Proclination of lower incisors in Class II Division 2 cases
An increased overbite can be corrected by proclining lower
incisors as they have been trapped (Mills, 1968). Though pro-
clination of lower incisors is considered unstable, in this mal-
occlusion, it is thought to be stable. Selwyn-Barnett proposed
that as the upper incisors intrude to resolve the deep overbite,
the lower incisors take up the positions previously occupied
by the uppers incisors (i.e. they procline). (Selwyn-Barnett,
1996)
Long-term retention plans
These include:
• A URA with a flat anterior bite plane (FABP) can be
used to maintain overbite correction
• Bonded retainers have been advocated.
• Some recommend bonded retainers and circumfer-
ential supra-crestal fibrotomy of rotated upper later-
als (Edwards, 1970).
and Day, 1974).
Aetiology
• Soft tissue factors.
• Dental factors.
• Growth factors.
Features of Class II Division 2 incisor relationships
Skeletal
• Usually mild Class II skeletal base but can be skeletal
I or III,
• Increased cranial base angle leading to mandibular
retrognathia (Hopkin et al., 1968),
• Longer cranial base leading to the prognathic max-
illa,
• Decreased lower face height, gonial angle, mandib-
ular plane angle and skeletal deep bite (Al-Khateeb
and Al-Khateeb, 2009).
• Maxilla may be short, broad and forward relative to
mandible leading to a tendency for scissor bite.
Soft tissue
• High resting lower lip line due to decrease lower
face height,
• Typically strap-like lower lip,
• Marked labio-mental fold.
• High masseteric muscle forces (Ingervall and Thi-
lander, 1974) (Sciote et al., 2012).
Dental
• Increase inter-incisal angle,
• Pronounced retroclination of the upper central inci-
sors (Brezniak et al., 2002),
• Retroclined upper and lower incisors,
• Upper laterals are often proclined, mesially tipped
and mesiolabially rotated (lower lip fails to cover
shorter crown),
• Deep bite (Brezniak et al., 2002) with reduced over-
jet and extruded upper incisors,
• Buccal segments are usually Class II,
• Scissor bite is common in the premolar region due
to transverse discrepancy,
• Crown-root angle (Collum angle) may be increased
(Feres et al., 2018),
• Incisors may be thin with a poorly defined cingulum
Exam night review
• LI edges occlude palatal to the cingulum plateau of
UI with retroclined UI & overjet usually minimal/
increased (BSI, 1983).
• If the overjet range of 5-7 mm & incisors are retro-
clined it is known as Class II intermediate.
• BSI Class II/2 classification based on incisor rela-
tionship
• Angle’s classification is based on the molar relation-
ship.
Incidence
• Class II/2 rare malocclusion, 2.3% and 5% of all
malocclusions in Caucasians (Ast et al., 1965) (Mills,
1966).
• United Kingdom 10% (Millett et al., 2012, Foster

Timing of treatment
• Cochrane review→ no evidence to recommend or
discourage any type of orthodontic treatment to cor-
rect Class II/2 malocclusion in children (Millett et
al., 2018).
Stability and retention
• Treat in timely manner to address overbite.
• Treat preferably non-extraction.
• Edge to centroid relation, IIA and move upper inci-
sors away from lower lip.
Retain long-term
• URA with flat anterior bite plane (FABP) with or
without bonded retainer upper labial segment.
• CSF of rotated upper laterals (Edwards, 1970).
(Robertson and Hilton, 1965).
References
AL-KHATEEB, E. A. A. & AL-KHATEEB, S. N. 2009. Anteroposte-
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AST, D. B., CARLOS, J. P. & CONS, N. C. 1965. THE PREVA-
LENCE AND CHARACTERISTICS OF MALOCCLUSION
AMONG SENIOR HIGH SCHOOL STUDENTS IN UPSTATE
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BASDRA, E. K., KIOKPASOGLOU, M. & STELLZIG, A. 2000. The
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BREZNIAK, N., ARAD, A., HELLER, M., DINBAR, A., DINTE, A.
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CANUT, J. A. & ARIAS, S. 1999. A long-term evaluation of treated
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DYER, F. M., MCKEOWN, H. F. & SANDLER, P. J. 2001. The
modified twin block appliance in the treatment of Class II division
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EDWARDS, J. G. 1970. A surgical procedure to eliminate rotational
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FOSTER, T. D. & DAY, A. J. 1974. A survey of malocclusion and
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HOPKIN, G. B., HOUSTON, W. J. & JAMES, G. A. 1968. The cra-
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HOPKINS, G., HOUSTON, W. & JAMES, G. 1968. The cranial base
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KARLSEN, A. T. 1994. Craniofacial characteristics in children with
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LAPATKI, B. G., MAGER, A. S., SCHULTE-MOENTING, J. &
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Quintessence Pub Co.

14
1. Classification of Class III malocclusion
2. Prevalence of Class III malocclusion
3. Aetiology of Class III malocclusion
4. Clinical features of Class III malocclusion
5. Treatment options for Class III malocclusion
6. Interceptive treatment
7. Growth Modification
8. Orthodontic camouflage treatment
9. Favourable features for orthodontic camouflage
10. Guidelines for orthodontic camouflage
11. Consideration of a single lower incisor extrac
tion
12. Bracket prescription can aid camouflage of the
Class III malocclusion
13. Dental decompensation and orthognathic sur-
gery
14. Surgical options
In this Chapter
Class III Malocclusion
Written by: Mohammed Almuzian, Haris Khan, Abbas Naseem, Taimoor Khan

134
Class III incisors relationship means that the incisal edge of
the mandibular incisors lies ahead of the cingulum plateau of
the maxillary incisors, according to the British Standard In-
stitute (BSI) classification (BSI, 1983). While Class III molars
relationship means that the mesiobuccal cusp of the perma-
nent maxillary first molar lies distal to the buccal groove of
the permanent first mandibular molar (Cobourne and DiBi-
ase, 2015). Class III canine relationship means that the upper
canine cusp tip lies posterior to the embrasure space between
the lower canine and the first premolar. The cephalometric
definition of Class III malocclusion is when the ANB angle
for the Caucasian population is less than 2° (Cobourne and
DiBiase, 2015).
Classification of Class III malocclusion
These include:
• True Class III malocclusion refers to the Class III
buccal occlusion bilaterally, with anterior crossbite
or edge to edge incisor relationship (Cobourne and
DiBiase, 2015).
• Pseudo-Class III malocclusion refers to the Class 1
skeletal relationship with bilateral buccal Class I oc-
clusion and anterior crossbite or edge to edge incisor
relationship due to functional anterior mandibular
displacement (Rabie and Gu, 2000).
• Class III subdivision (asymmetry) refers to Class III
buccal occlusion on one side (subdivision) and Class
I on the other (Janson et al., 2010).
Classification Class III malocclusion based on the severity
Overjet based classification (Proffit et al., 2006) include:
• Mild Class III- 0 mm
• Moderate Class III -1 to -2mm
• Severe Class III -3 to -4 mm
• Extreme >-4 mm
Cephalometry based classification is based on the magnitude
of the ANB angle ( Kerr et al., 1992) and includes::
• Mild Class III >-2°
• Moderate Class III -2°to -4°
• Severe Class III <-4°
Prevalence of Class III malocclusion
Low prevalence in the western population, ranging from
3-5% (Todd and Lader, 1991, Cobourne et al., 2012). How-
ever, higher a prevalence has been reported in the Asian
population of 13% (Xue et al., 2011). The incidence of an-
terior crossbite in the Caucasian population is around 10%
(O’Brien, 1994).
Aetiologies of Class III malocclusion
Two significant factors have been identified in the aetiology
of the Class III malocclusion (Singh, 1999):
1. Positional cause: Due to the change in skeletal position,
shown in cephalometric angular measurements due to altera-
tion in growth pattern.
2. Quantitative cause: It is reflected as linear measurements
due to a size alteration due to craniofacial overgrowth beyond
normal limits.
Aetiological factors can be summarised into:
1. Genetic factors: Class III malocclusion is believed to be
inherited genetically due to its familial tendency (Hapsburg
jaw). Mandibular prognathism can also be caused by certain
X-chromosome aneuploid conditions (abnormal number of
chromosomes in a haploid set).
2. Environmental factors such as (Gottlieb and Gottlieb,
1954):
• Enlarged tonsils (Proffit et al., 2006).
• Premature loss of the first molars.
• Macroglossia.
• Cleft lip and palate and scarring secondary to cleft
repair.
• Disease of the pituitary gland and associated hor-
monal disturbances, for example, acromegaly.
• Trauma and irregular eruption of permanent inci-
sors or loss of deciduous incisors (Gorlin et al., 1965,
Angle, 1907).
• Other contributing factors are the relative position
and size of the cranial base, maxilla, mandible and
temporomandibular articulation (Gold, 1949, Jena
et al., 2005, Hopkin et al., 1968, Battagel, 1993).
Clinical features of Class III malocclusion
These include:
1. Skeletal features such as:
• Short anterior cranial base.
• Short posterior cranial base.
• Maxillary retrusion (25%).
• Mandibular prognathism (18.7%).
• Combination of both retrognathic maxilla and
prognathic mandible (22.2%).
• Anterior position of TMJ (Chen et al., 2008).
• Increased mandibular length.
• Obtuse gonial angle.

Class III Malocclusion 135
• Usual skeletal Class III or Class I relationship (Guy-
er et al., 1986, Cobourne and DiBiase, 2015)
• Increased lower facial height where mandibular
prognathism is present.
• Decreased lower facial height where maxillary re-
trusion is present.
• Transverse skeletal discrepancy (Severt and Proffit,
1997).
• Mandibular asymmetry is common.
• Class III incisor relationship (edge-to-edge incisor
relationship, or reverse overjet) (Guyer et al., 1986,
Cobourne et al., 2012),
• Reduced overjet.
• Class III molar relationship, but can vary.
• The range of overbite relationships can be observed.
• Dental compensation for the skeletal Class III, i.e.
proclined maxillary incisors and retroclined man-
dibular incisors.
• Crowding is more pronounced in the maxillary arch
if the aetiology is maxillary retrusion.
• A Displacement is frequently observed due to den-
tal interferences (edge to edge incisor relationship,
or inadequate transverse relationship) (Gu and Jr,
2007).
3. Soft tissue features (Jin-jong, 2008) such as:
• Decreased angle of convexity; concave facial profile.
• The lower lip may be full with a thin upper lip (Guy-
er et al., 1986, Cobourne and DiBiase, 2015),
• Hypotonicity of mentalis muscle.
• Increased throat length.
• Obtuse nasolabial angle (Singh, 1999)
4. Facial growth features such as:
• Unfavourable growth
• The Mandible shows considerable variation in the
rate, timing and overall extent of growth.
• There are also individual changes in the growth that
contribute to the development of the malocclusion
(Cobourne and DiBiase, 2015). The most significant
increase in mandibular growth occurred in the cer-
vical maturation stage interval CS3-CS4 and a small-
er amount in CS5-CS6.
A. Sagittal cephalometric features (Zegan et al., 2015, San-
born, 1955)
• Decreased SNA angle.
• Increased SNB angle.
• Decreased AO-BO distance. i.e. BO ahead of AO
with Wits analysis.
• Increased SN-Pug angle.
• Decreased cranial base angle, N-S-Ba angle (Thiesen
et al., 2013).
• Decreased anterior cranial base length, S-N.
• Decreased posterior cranial base length, N-Ba.
• Increased mandibular corpus length.
B. Vertical cephalometric features
• Increased FMA.
• Increased MMPA.
• Increased anterior face height, N-Mn.
• Decreased saddle angle, N-S-Are angle.
• Decreased joint angle, S-are-Go angle.
• Obtuse gonial angle, Ar-Go-Mn angle.
C. Dental cephalometric features
• Increased UI-SN and UI-Maxillary plane angle.
• Decreased LI-MP angle.
• Increased Holdaway ratio.
D. Soft tissue cephalometric features
• Decreased Ls-E-line
• Increased Li-E-line.
• Obtuse nasolabial angle.
Treatment options for Class III malocclusion
• Interceptive treatment (Graber et al., 2016).
• Growth modification.
• Decompensation followed by orthognathic surgery.
• Orthognathic surgery followed by dentoalveolar de-
compensation (surgery first)
Interceptive treatment
Upper removable appliance or 2 x 4 fixed appliance (2 brack-
ets on the first molars and 4 brackets on the incisors) are in-
dicated when tipping movement is required, and the overbite
is positive. Evidence showed that fixed appliances are supe-
rior to URAs in the cost-effectiveness and treatment duration

136
(Wiedel and Bondemark, 2016, Wiedel et al., 2016). Fixed
appliance treatment could be combined with anterior cross
elastics and/ or molar bite block disocclusion (Reynolds,
1978, Tzatzakis and Gidarakou, 2008).
Growth Modification
These include:
1. Protraction Facemask (PFM)
PFM is advocated as an orthopaedic appliance for manag-
ing a Class III malocclusion in growing patients (McNamara,
1987, Graber et al., 2016). PFM is the appliance of choice in
the early mixed dentition or late primary dentition, ideally
when the permanent maxillary incisors erupt (approximately
8 years) but to a lesser degree in patients older than 10 years
of age (Kim et al., 1999).
PFM has three essential components: an extraoral protraction
mask, an intraoral bonded maxillary splint and elastics (used
from the extraoral mask to the intraoral maxillary splint).
A bonded acrylic splint expander can be added if maxillary
constriction is present or a discrepancy between centric rela-
tion and centric occlusion.
Controversy exists over the requirement of RME before PFM
use. A meta-analysis found that PFM with or without RME
treatment is an effective early treatment method for skeletal
Class III malocclusion (Zhang et al., 2015). On the other
hand, another meta-analysis concluded that PFM therapy
was less effective in patients greater than 10 years of age with
a longer treatment time if RME was not used (Mandall et al.,
2016).
A recent meta-analysis found the low quality of evidence sug-
gesting that on a short-term basis, alternate rapid maxillary
expansion and constriction (Alt-RAMEC) combined with
maxillary protraction results in a more remarkable skeletal
sagittal improvement, with more maxillary protraction and
less mandibular clockwise rotation when compared with the
conventional approach (RME/PFM) (Almuzian et al., 2018).
A Cochrane review found that using a facemask to correct
prominent lower front teeth in children is effective when com-
pared with no treatment on a short-term basis (Watkinson et
al., 2013). PFM has a short-term skeletal effect and long-term
dentoalveolar effects (Woon and Thiruvenkatachari, 2017,
Jamilian et al., 2016). PFM seems to correct Class III discrep-
ancies but decreases the overbite due to clockwise rotation of
the jaw (Rongo et al., 2017). Evidence showed that patients
were also less likely to have orthognathic surgery if they had
facemask treatment at an early age, 36% compared with 66%
of the control group (Mandall et al., 2016). The post PFM
retention phase includes a simply fixed plate, Frankel III or
a chin cup, though a combination of these can also be used
(Almuzian et al., 2018).
2. Chin cup therapy
Chin cup therapy is advocated for treating developing Class
III malocclusions in the primary and early mixed dentition,
where prognathic mandibular growth is mild to moderate in
nature (Thilander, 1965). It is not indicated for severe reverse
overjet, open bite, maxillary hypoplasia aetiology and lower
incisor compensation. A chin cup causes lingual tipping of
the lower labial segment and clockwise rotation of the man-
dible.
A variety of chin cups types are available to alter the verti-
cal vector to manage the vertical proportions (Graber et al.,
2016). A systematic review concluded insufficient evidence-
based data to make definitive recommendations about the
chin cup treatment (Chatzoudi et al., 2014).
3. The Frankel III (FR-3) appliance
The FR-3 appliance aids to restrict the forces of the associated
soft tissue on the maxilla and transmits these forces to the
mandible (Graber et al., 2016). The FR-3 appliance is effective
in the mixed-dentition period however long-term stability
depends on future growth (Ko et al., 2004). Evidence shows
that the FR-3 appliance might restrict mandibular growth but
doesn’t enhance forward movement of the maxilla (Sugawara
and Mitani, 1997).
4. Bone anchored maxillary protraction/Bollard plates
(BAMP)
BAMP involves the placement of mini-plates in the infra-
zygomatic region and the canine- lateral incisors region in
the mandible. Class 3 elastics are attached to the mini-plates
to transfer force for the Class III correction (Yang et al., 2014,
Graber et al., 2016, Al-Mozany et al., 2017).
BAMP is commonly used at 11 years of age in girls and 12
years in boys to ensure maximum bone rigidity, optimise the
stability of anchored plates, and reduce the risk of trauma-
tising developing dental follicles. One of the drawbacks of
BAMP is the surgical invasiveness of the technique, especially
in young children (Hino et al., 2013, De Clerck et al., 2010,
Graber et al., 2016). There is controversy about the intraoral
and extraoral benefits of skeletal anchored maxillary pro-
traction (SAMP), including BAMP. According to a system-
atic review by Major, greater orthopaedic changes and fewer
dental changes occur with SAMP (Major et al., 2012). How-
ever, another meta-analysis found that SAMP is as effective
as other traditional treatments, such as a PFM (Rodriguez de
Guzman-Barrera et al., 2017).
Orthodontic camouflage treatment
The aims of orthodontic camouflage of a Class III malocclu-
sion are:
• Proclination of upper incisors.
• Retroclination of lower incisors.

• Protrusion of the maxilla.
• Backward rotation of the mandible to decrease the
prominence of point “B”,
• Combination of the above.
• Increase of the vertical dimension.
Favourable features for orthodontic camouflage
These include:
• Patient has completed their growth spurt.
• Near to normal soft tissue profile.
• Normal or mild transverse relations.
• No apparent facial asymmetry.
• Mild skeletal discrepancy.
• Adequate vertical relationship and decreased over-
bite.
• In the absence of displacement, the patient can
achieve edge to edge bite in RCP.
• Minimal dento-alveolar compensation.
• Mild lower arch crowding (allowing extraction ther-
apy to correct the overjet).
Guidelines for orthodontic camouflage
These include:
• The upper incisors should not be proclined beyond
120° to the maxillary plane (Burns et al., 2010).
• The lower incisors should not be retroclined less
than 80° to the mandibular plane to avoid bone fen-
estrations and gingival recession, particularly in the
thin gingival biotypes (Burns et al., 2010).
• If extractions are indicated to relieve crowding in
the lower arch, extractions of anterior teeth are pre-
ferred to aid retraction of the lower labial segment.
• If extractions are indicated in the upper arch, ex-
tractions of posterior teeth are preferred to prevent
retraction of the upper labial segment.
• Occlusal stability is greater if a positive overbite
is achieved at the end of the treatment and future
growth is minimal.
Consideration of a single lower incisor extraction
These include:
• To facilitate retroclination of the lower incisors, clos-
ing space on an under-sized rectangular or round
stainless steel wire is favourable.
• Class 3 elastics may be required to facilitate procli-
nation of the upper incisors and retroclination of the
lower incisors.
Bracket prescription can aid camouflage of the Class III
malocclusion
These include:
• High palatal root torque prescription in the upper
incisors brackets.
• Labial root torque in the lower incisor brackets
• Bracket modification through swapping lower ca-
nine brackets is recommended to prevent the mesial
tipping of lower canines.
Dental decompensation and orthognathic surgery
Indications (Graber et al., 2016) such as:
• No residual growth, i.e. in late teens.
• Severe Class III malocclusion where orthodontic
camouflage is not possible.
• Significant vertical or transverse discrepancies.
Surgical options are:
• Mandibular surgeries include bilateral sagittal split
osteotomy or vertical sub-sigmoid ramus osteotomy
to reposition the mandible posteriorly for cases with
mandibular prognathism.
• Maxillary surgeries include Le-Fort I or modified
Le-Fort I advancement for cases with maxillary skel-
etal retrusion.
• Bimaxillary osteotomy may be used simultaneously
in instances of maxillo-mandibular skeletal imbal-
ances.
Exam night review
• BSI classification→ Class III malocclusion incisal
edges of the mandibular incisors lie ahead of the cin-
gulum plateau of the maxillary incisors (BSI, 1983).
• Class III molar relationship→MB cusp of U6 lies dis-
tal to BG of L6 (Cobourne and DiBiase, 2015).
• Class III canine relationship→long axis of the upper
canine lies or occludes distal to the embrasure of the
lower mandibular canine and the first premolar.
• Class III ANB 2° Caucasian (Cobourne and DiBi-
ase, 2015).
Classification of Class III malocclusion

138
• True Class III
• Pseudo-class III (Rabie and Gu, 2000).
• Class III subdivision (Janson et al., 2010).
Prevalence of Class III malocclusion
• Western population 3-5% (Todd and Lader, 1991,
Cobourne et al., 2012).
• 13% Asian population (Xue et al., 2011). Anterior
crossbite Caucasians 10% (O’Brien, 1994).
Aetiology of Class III malocclusion
1. Genetic factors
2. Environmental factors
• Enlarged tonsils (Proffit et al., 2006).
• Premature loss of the first molars,
• Macroglossia,
• Cleft lip and palate and scarring secondary to cleft
repair,
• Disease of the pituitary gland and the associated
hormonal disturbances
• Trauma and irregular eruption of permanent inci-
sors or loss of deciduous incisors (Gorlin et al., 1965,
Angle, 1907),
• Other factors (Gold, 1949, Jena et al., 2005, Hopkin
et al., 1968, Battagel, 1993)
Classification of the severity of Class III Malocclusion
mild >-2 , moderate -2°to -4°,severe: <-4°
Treatment options
• Interceptive treatment (Graber et al., 2016).
• Growth modification.
• Decompensation followed by orthognathic surgery.
• Orthognathic surgery followed by dentoalveolar de-
compensation (surgery first)
Growth Modification
• Protraction Facemask (PFM)
• Chin cup therapy
• The Frankel III (FR-3) appliance:
• Bone anchored maxillary protraction/Bollard plates
(BAMP)
Aims of orthodontic camouflage treatment
• Proclination of the upper incisors.
• Retroclination of the lower incisors.
• Protrusion of maxilla.
• +ve rotation of mandible → prominence of point
“B”.
Favourable features for Orthodontic camouflage (Co-
bourne and DiBiase, 2015)
• The patient completed a growth spurt.
• Near to normal soft tissue profile.
• Normal or mild transverse relations.
• No obvious facial asymmetry.
• Mild skeletal discrepancy.
• Adequate vertical relationship and average overbite.
• In the absence of displacement, the patient can
achieve edge to edge bite in RCP.
• Minimal dento-alveolar compensation.
• Mild lower arch crowding to optimise the uses of ex-
traction spaces to correct the overjet.
Guidelines for Orthodontic camouflage
• UI 120° to PP
• LLS 80° to MP
• lower single incisor extraction to retrocline LLS.
• For retroclination of LI, closing space on an under-
sized rectangular or round stainless steel wire.
• Class 3 elastics to procline UI & retrocline LI.
• To camouflaging, +ve torqued UI brackets & -ve
torqued LI brackets along with swapping of lower
canine brackets.
• Stability→ overbite & future growth.

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15
1. Types of maxillary skeletal deficiency
2. Benefits of treating displacement
3. Incidence of transverse maxillary deficiency
4. Age-related changes in maxillary dimension
5. Aetiology of transverse maxillary deficiency
6. Clinical features of transverse maxillary defi
ciency
7. Diagnosis of transverse maxillary deficiency
8. Treatment objectives
9. How much expansion is required?
10. Non-surgical maxillary expansion
11. Principle of RME
12. The rationale for expansion treatment
13. Types of conventional RME
14. The influence of the height of RME
15. Proposed Indications for RME
16. Contraindications and limitations of conven
tional RME
17. Potential complications of RME
18. Mid-palatal suture assessment methods
19. Mid-palatal suture maturation classifica-
tion
20. Interpretation mid-palatal suture maturation
classification:
21. Mid-palatal suture density ratio
22. Protocols of maxillary expansion
23. Modern designs of RME/ Mini-implant assisted
rapid palatal expansion (MARPE)
24. Surgical maxillary expansion
25. Indications for SARPE
26. Complications during SARPE
27. Retention and stability secondary to MPMO
28. Factors & Yardsticks
29. Appliances for unilateral maxillary expansion
30. Treatment of scissor bite
31. Stability and retention of expansion
32. Anterior crossbites
33. Requirement for the successful result using URA
In this Chapter
Transverse arch
discrepancY
Written by: Mohammed Almuzian, Haris Khan, Maham Munir, Abbas Naseemn

Maxillary Transverse Arch Discrepancy
142
Transverse maxillary deficiency is defined as a constricted
maxilla relative to the mandible (Proffit et al., 2006). It can
manifest with the following:
• Anterior crossbite: The upper anterior teeth are palatally
positioned in their relationship to the lower anterior
teeth (Prakash and Durgesh, 2010).
• Posterior crossbite: In centric relation, the upper poste-
rior teeth are palatal relative to the opposing lower pos-
terior teeth. This is the most common type of crossbite
(Andrade et al., 2009).
When there is a discrepancy, the mandible encounters a de-
flecting contact, which is displaced. Displacements can be
anterior, posterior or lateral.
Different terminologies in transverse maxillary deficiency
These include:
• Crossbite: A discrepancy of the tooth relationship in
the transverse plane of space (BSI, 1983).
• Buccal crossbite: The buccal cusps of the mandibu-
lar teeth occlude laterally or buccally to the buccal
cusps of the maxillary teeth (BSI, 1983).
• Lingual crossbite: The buccal cusps of the mandibu-
lar teeth occlude lingually to the palatal cusps of the
maxillary teeth.
• Unilateral crossbite: Crossbite affects one side of the
dental arch, which may or may not be associated
with functional mandibular displacement (Palla and
N, 2018).
• Bilateral crossbite: Both sides of the dental arch are
affected and are in crossbite.
• Crossbite tendency: The tooth-to-tooth contact in
the transverse plane are in edge to edge relationsip
in the occlusion (Grammatopoulos et al., 2012).
• Displacement: The functional deflection of the
mandible on closing from retruded contact position
(RCP) to the intercuspal position (ICP). There is a
discrepancy between the muscular positioning of
the mandible (centric position) and that dictated by
the teeth coming into the occlusion (centric occlu-
sion) (Cobourne et al., 2012).
• Upper inter-molar width: The distance between the
mesiobuccal cusps tips of the right and left maxillary
first molars (Garino and Garino, 2002), or the dis-
tance between the central fossae of the permanent
maxillary molars on the right and left sides (Lux et
al., 2003).
• Lower inter-molar width: The distance between the
cusp tips of the distobuccal cusps of the right and left
first mandibular molars or the distance between the
most cervical extension of the buccal grooves on the
mandibular first molars (Garino and Garino, 2002).
• Palatal width: Minimum distance at the gingival lev-
el between maxillary first molars (Lux et al., 2003) or
the distance between the mesio-lingual cusp tips of
the first molars (Isaacson et al., 1971).
• Trans-palatal width: The distance between the right
and left gingival ends of the palatal grooves of the
maxillary first molars.
• Telescopic bite: Bilateral mandibular lingual cross-
bite. The mandibular posterior teeth are lingual to
the maxillary teeth.
• Brodie bite: Unilateral or bilateral complete poste-
rior buccal crossbite, also called Brodie syndrome.
It is a severe transverse discrepancy when all buccal
cusps of the lower molars are telescoped within the
lingual cusps of the upper molars (Valencia, 2007).
Incidence is around 1.0% to 1.5%.
Types of maxillary skeletal deficiency
There are two types of maxillary skeletal deficiency (Haas,
1965, Kutin and Hawes, 1969):
• Relative maxillary deficiency: when the maxilla is
of normal size compared to the upper face and the
cranium, the mandible is comparatively large.
• Real maxillary deficiency: The maxilla size is small
compared to the mandible and midface. Upper
posterior teeth can either be on the basal bone or
inclined buccally to occlude the mandibular teeth
(transverse compensation).
• Haas introduced the terms relative and absolute
transverse discrepancy (Haas, 1961):
• Relative transverse discrepancy: This is due to an-
tero-posterior positioning of the mandible.
• Absolute transverse discrepancy exists when the
posterior teeth do not coordinate in centric relation
or on dental models when canines are placed into a
Class I relationship.
Benefits of treating displacement
These include:
• Aesthetic benefits by widening the buccal corridor
• Eliminate the undesirable growth, which can result
in mandibular displacment and eventually to true
mandibular asymmetry
• Potentially avoid TMD in the susceptible patient
(weak evidence)

Maxillary Transverse Arch Discrepancy 143
• Avoid exacerbation of plaque related periodontal
damage.
• Avoid tooth surface loss.
Incidence of transverse maxillary deficiency
The incidence of transverse maxillary deficiency is 8-22%
(Andrade et al., 2009), while the prevalence of posterior
crossbite is 7.7%. Moreover, the prevalence of anterior cross-
bite is 10 % (Allen et al., 2003, O’Brien, 1994). Functional
mandibular displacement towards the crossbite is found in
80-97% of the cases (Thilander et al., 1984).
Age-related changes in maxillary dimension
Arch dimensions change with growth. It is, therefore, nec-
essary to distinguish changes induced by appliance therapy
from those that occur from natural growth. Both upper and
lower inter-canine widths increase from the 6th year up to 13
years in both genders, increasing more prominent in the up-
per arch. From 13 to 45 years, inter-canine widths decrease.
Maxillary and mandibular inter-molar widths continue to
increase until the age of 13 in both genders. However, there
is a slight decrease in widths for females from periods 13-45
years with no change in male inter-molar width (Bishara et
al., 1997).
Bjork’s study
• Inter-canine width increases until the full eruption
of the permanent incisors, after which there is a con-
tinuous decrease up to adult age.
• Mid-palatal growth was found to cease by the age of
17 years.
• Posterior maxillary growth was more than anterior
growth with transverse rotation (Björk and Skieller,
1974).
Other studies showed that:
• Transpalatal width increased only 2.6 mm from age
7 to 15. After 12 years of age, there is no change for
females and very little increase (about 1mm) for
males in both maxilla and mandible (McNamara et
al., 2001)
• The inter-canine widths of upper and lower arches
tend to decrease slightly during the permanent den-
tition (around 12 years old) for both males and fe-
males (Bishara et al., 1997).
Aetiologies of transverse maxillary deficiency
The causes of maxillary constriction may include dental, soft
tissue and skeletal components and are listed below (Allen et
al., 2003, Andrade et al., 2009):
• Hereditary
• Habits such as thumb sucking
• Trauma or pathology
• Obstruction of the upper airway due to the enlarged
adenoids
• Nasal allergies
• Mouth breathing during growing years
• Cleft lip and palate
• Arch length discrepancy and crowding
• Over-retained or an early loss of deciduous teeth
• Abnormal tooth anatomy
• Iatrogenic causes, for example, surgical correction
of the cleft lip and palate.
Clinical features of transverse maxillary deficiency
Transverse maxillary deficiency has the following common
clinical manifestations (McNamaraa, 2000):
• Upper arch crowded.
• Unilateral or bilateral crossbite with or without
functional jaw displacement.
• Buccally flared upper posterior teeth.
• Wide buccal corridors.
• Narrow and high palatal vault. (Proffit et al., 2006).
• ‘V’ or triangular shaped maxilla.
• Impacted teeth due to constricted anterior maxilla
(McConnell et al., 1996).
Diagnosis of transverse maxillary deficiency
These include:
1. Recording functional jaw displacement: Record any func-
tional jaw displacement from RCP to ICP in direction and
quantity. Absence of displacement indicates that the crossbite
is of a skeletal origin (Piero, 2006).
2. Study model measurements: Measure the palatal width
(X) and the lower inter-molar width (Y) on the study model
(Proffit et al., 2006). Distances between the midpoint of teeth
could be measured in mm and compared to a tabulated tem-
plate (Moyers, 1976).
3. Radiography: A Posterior-Anterior (PA) cephalogram or
CBCT can be used to calculate transverse skeletal discrep-
ancies between the maxilla and the mandible (Allen et al.,
2003). The following measurements can be recorded:
• Effective maxillary width (JL-JR): The distance be-
tween JL and JR (bilateral points located at a depth
of concavity of the lateral maxillary contour, at the
junction of the maxilla and zygomatic buttress).

144
• Effective mandibular width (AG-GA): The distance
between AG and GA points (bilateral points at the
inferior margin of the antegonial protuberance).
• Maxillomandibular transverse differential: The
maxillomandibular differential width (Ag-Ag and
J-J) compared with Ricketts’ normal values of the
same age. A difference within 5mm is average; how-
ever, a transverse skeletal problem exists if it is more
than 5mm. The Maxillomandibular transverse dif-
ferential limitations are significant errors in land-
mark identification of point Ag and J (Chung, 2019)
and no consensus transverse norm values.
CBCT evaluation
With the advent of cone-beam computed tomography
(CBCT), the following can be accurately determined to assess
in diagnosis and treatment planning:
• Widths of maxillary and mandibular basal bones
and their relationship.
• Buccolingual inclination of each tooth.
• Root position in the alveolar bone.
Treatment objectives
The following treatment objectives should be considered
(Chung, 2019):
• The maxillary basal bone should be expanded to the
point that the palatal cusps of maxillary molars oc-
clude beyond the central fossae of mandibular mo-
lars.
• Normal curve of Wilson should be achieved for the
ideal occlusal function. However, excess in the curve
of Wilson results in occlusal interferences (Nanda,
2005).
How much expansion is required?
Generally, the required amount of expansion is the differ-
ence between the buccal cusp widths of lower molars and
the central fossa widths of the upper molars; the normal val-
ues are +1.6mm for males and +1.2mm for females (Chung,
2019). Ideally, molars should be over-expanded by 2 to 4mm
to compensate for the expected post-expansion relapse. To-
tal expansion includes skeletal expansion (true mid-palatal
suture expansion) and/ or dental expansion (dental tipping
and alveolar bone bending) (Zong et al., 2019). The follow-
ing treatment modalities have been suggested based on the
degree of the discrepancy:
• 2-3mm = Upper removeable
• 4-5mm = Quad-helix
• 5-6mm = RME (growing patients)
• More than 6mm = MARPE or SARPE in non-grow-
ing patients (Suri and Taneja, 2008).
Non-surgical maxillary expansion
1. Removable expansion appliances such as:
A. Upper removable appliance with expansion screw (Almu-
zian et al., 2016, Gill et al., 2004): A slow maxillary expander
consists of an upper acrylic removable appliance, incorporat-
ing a midline expansion screw. Retention can be achieved us-
ing Adam’s clasps on premolars and first molars. A posterior
bite plane is added for bite raising if required. The appliance
produces mostly dento-alveolar expansion by tipping molar
teeth buccally with little skeletal effect. For symmetrical ex-
pansion (most common), the baseplate of the appliance is di-
vided, with an equal number of anchor molars on either side
of the midline. Theoretically, asymmetric expansion can be
undertaken by incorporating more teeth on the anchor side
and less on the movement side. After expansion, the appli-
ance should remain passive for 3 - 4 months for retention.
B. Upper removable appliance with Coffin spring: A 1.25
mm round stainless-steel wire is incorporated in the design
of the upper removable appliance. The spring is either bent
into an Omega-loop or a diamond shape; hence, it is some-
times called an Egg-shape appliance. The appliance is acti-
vated by pulling the two halves of the appliance apart by 2
– 3 mm. Adam’s plier could also be used for activation of the
central loop.
C. Functional appliances: This can be achieved either by ac-
tive expansion, usually with expansion screw or palatal arch,
or by passive expansion by removing buccal tissues’ influence
with buccal shields (Frankel appliance).
Pros and cons of removable expanders
These include:
• They can easily incorporate other active compo-
nents such as springs,
• Expansion component can be part of a functional
appliance such as a twin block.
• They rely on patient compliance.
• It is a less well-tolerated appliance with poor reten-
tion.
• They produce mainly dental changes.
• As buccal tipping of the molars occurs, the palatal
cusps tend to drop down, and this can cause overbite
reduction and increase of the MMPA.
• Expansion is mainly dento-alveolar.
2. Fixed expansion appliances such as:
A. Quadhelix appliance: It can be custom made or a pre-
formed ready type. The device is fabricated from 1.0-0.9 mm
stainless steel wire. It incorporates four helices into the ‘W-

spring’, which increases the flexibility and range of activation
by increasing the length of the spring’s wire. Molar bands are
used for retaining the appliance on the first molars with glass
ionomer cement. Quadhelix consists of anterior helices and
a pair of posterior helices. The wire portion between the two
anterior helices is called the anterior bridge, and the wire be-
tween the anterior and posterior helices is called the palatal
bridge. The free wire ends adjacent to the posterior helices are
called outer arms. Different versions of the Quadhelix have
been proposed. The nickel-titanium versions have been in-
troduced, offering more favourable force delivery character-
istics. Bi-helix design can expand the narrowed or distorted
mandibular arch to aid correction of a severe scissors bite.
Before bone grafting, the trihelix design is used as an expan-
sion appliance in the cleft palate. In pre-pubertal children,
Quadhelix produces 6:1 buccal tipping to skeletal expansion.
B. Activation is undertaken either with manual stretching
of the appliance or using a three-prong plier. A desirable
force level of 300-400 grams/ side is usually achieved when
activating half a tooth’s width on each side. However, over-
correction is desirable. It is advisable to retain the corrected
results for 3 months using either the same appliance in a pas-
sive mode, upper removable appliance or TPA with extended
arms. A Cochrane review concluded that a quad‐helix is 20%
superior to removable expansion appliances (1.15 mm more
expansion) in correcting posterior crossbites in children aged
8-10 years (Agostino et al., 2014). Another systematic review
found a greater success rate and compliance using a quad-
helix when compared to removable appliances (Zuccati et al.,
2013).
Advantages of Quadhelix appliance
These include:
• It has optimum retention.
• No compliance is needed.
• It has a good range of activation.
• It can derotate molars.
• It can be used as a habit breaker.
• It can expand the upper arch anteroposteriorly when
its arm’s length increases.
• It can provide anchorage in AP and transverse di-
rections.
• It can be a method for attachments to align impact-
ed teeth or perform certain teeth movement.
Disadvantages of Quadhelix appliance
These include:
• Little orthopedic change can be achieved.
• It mainly produces the tipping of molars.
• It has a bite opening effect.
• Sometimes, the appliance can imprint the tongue;
however, this will rapidly disappear following treat-
ment.
C. Expansion (E) Arch (McNally et al., 2005): It is also called
Mulligan overlay archwire. In principle, it is similar to the first
E-arch, which Edward Angle introduced in 1887. The expan-
sion arch is made of round stainless-steel wire (1.135 mm),
bent into a wide dental arch. It is inserted into the headgear
tubes on the upper first molar bands or positioned over the
main archwire ligated in place. According to a randomised
control trial, both the quad-helix and the expansion arch
were equally effective in the expansion if similar force levels
were used. Quadhelix causes discomfort to the tongue while
the expansion arch interferes with the cheeks. However, the
expansion arch has the advantage of being cheap and requir-
ing less chair-side time to place than Quadhelix (McNally et
al., 2005).
3. Fixed appliances expansion techniques: Expansion can
be obtained during fixed appliance treatment in a variety of
ways, including:
• The use of overexpanded stainless steel archwires,
typically using 0.019 x 0.025 or 0.021 x 0.025 with
reduced progressive buccal root torque.
• Cross elastics run from the palatal aspect of upper
teeth to the buccal aspect of lower teeth. However,
there will also be a vertical component of a force that
will tend to extrude molars; therefore, it is contrain-
dicated in high angle cases.
4. Rapid Maxillary Expansion RME (Maxillary suture ex-
pander)
Principle of RME
Skeletal expansion treatment involves mid-palatal suture sep-
aration and widening the palatal shelves, which widens the
floor of the nose and roof of the mouth. The palatal expansion
can be performed at any time before the completion of the
growth spurt (CVMS2 and CVMS3). Later, with age increase,
the mid-palatal suture becomes more tightly interdigitated,
forcing relatively heavy forces to separate.
The rationale for expansion treatment
The effects of RME in achieving maxillary expansion are:
• Buccal tipping or bodily movement of the teeth
• Alveolar bone bending due to the resilient nature of
the alveolar bone
• Separation of the mid-palatal suture, with induction
of new bone formation.
The relative amounts of these changes vary depending on the
type of appliance used, rate of activation, and the patient’s

146
age. These effects can be achieved by using a rigid appliance
(to limit tipping of the molars) and applying heavy and rapid
forces (to exceed the rate of dental movement and produce
splitting of the suture). The midpalatal suture opening is fan-
shaped or triangular with a maximum opening at the incisor
region but gradually diminishing towards the posterior part
of the palate. The fan-shaped or non-parallel opening is also
seen in the superior-inferior direction. The maximum open-
ing is towards the oral cavity, which progressively reduces in
the direction of the nasal aspect.
Types of conventional RME
RMEs can be divided into three types depending on how the
appliance is retained (Almuzian et al., 2016):
a) Banded: A systematic review comparing different tooth-
borne RME appliances, 4-band appliances are indicated when
anterior crowding is present within a tapered arch. 2-band
appliances are more effective when mild crowding in the pos-
terior regions is present (Zuccati et al., 2013).
• Tooth-borne: e.g. HYRAX/ Biedermann and Isaac-
son appliances
• Tooth and tissue borne: e.g. Haas and Derichsweiler
appliances
b) Bonded appliance: Mostly tooth-tissue borne.
c) Hybrid HYRAX: Tooth and bone-borne (retention from
teeth and TADs).
Depending on the appliance design, RMEs can also be divid-
ed into (Almuzian et al., 2016):
• HYRAX (HYgienic RApid eXpander) is a tooth-
borne appliance, and it consists of an expansion
screw that is soldered/welded to molar bands on
abutment teeth.
• The Isaacson appliance is tooth-borne and also
known as the ‘Minne-Expander’. It is similar to a
HYRAX appliance, except the expansion screw is
replaced with coil spring, activated by turning a key
to compress the spring. The disadvantage of this ap-
pliance is that it produces a continuous force.
• The Haas appliance consists of an expansion screw
with buccal and palatal connectors from the screw
to a palatal plate (acrylic or metal). According to a
randomised clinical trial comparing expansion with
HYRAX and a Haas appliance, the latter had a more
orthopaedic effect with less tipping tendency of the
maxillary first molars (Weissheimer et al., 2011).
• Derichsweiler is comparable to the Haas design ex-
cept for the absence of buccal connectors.
• The bonded RME appliance consists of either cobalt
chrome housing of the dentition and connector to
the screw or acrylic capping of the posterior denti-
tion and acrylic connector to the screw. This design
is associated with an increased risk of decalcifica-
tion.
The influence of the height of RME
If the the screw is close to the palate, an extrusive tenden-
cies of the posterior teeth are expected when the screw
is placed above the centre of the teeth and nearer to the
palate. If the screw is away from the palate, more buccal
crown tipping is expected when the hyrax screw is far
away from the palate.
Proposed indications of the RME
The following are the proposed indications of the RME (Gill
et al., 2004):
• Crossbite correction (unilateral or bilateral): The
short-term outcomes of RME are 4:1 skeletal to den-
tal expansion, but over time, this ratio reduces to 1:1.
• Broadening the smile (Moore et al., 2005).
• In a ‘V-shaped’ arch form due to para-functional
habits.
• Following Class II growth modification to correct
the relative crossbite created through advancing the
mandible relative to the maxilla.
• To facilitate maxillary protraction with protraction
facemask therapy.
• Interceptive treatment of impacted canines (Baccetti
et al., 2011, Pavoni et al., 2013).
• Preparation for the grafting procedure in a cleft al-
veolus (Shaw and Semb, 1990).
• Space creation: For every 1mm of increase in the
inter-molar width, there is 0.6mm of relief of crowd-
ing and 0.3mm of overjet reduction (O’Higgins and
Lee, 2000).
• Expansion in conjunction with upper molar distali-
sation.
• Orthopaedic expansion of the narrow upper arch:
Conflicting evidence regarding the pattern of the
expansion is present; some authors concluded that
the expansion is pyramidal with the more anterior
expansion than posterior, while others concluded
that the ratio of inter-canine to inter-molar width
increase with RME is 0.75:1 respectively (Gopal-
akrishnan and Sridhar, 2017). The overall quality of
evidence was generally low (Liu et al, 2015). A sys-
tematic review concluded that the effect of RME on
the mid-palatal suture ranges from 12 – 52.5% of the
total screw expansion. Some authors consider RME
a possible option in patients greater than 15 years of

age (Bishara and Staley, 1987, Wertz, 1970), however
according to an autopsy study of mid-palatal su-
tures, most fuse by 15 years of age (Melsen, 1975). In
light of this study, RME should be prescribed before
this age.
• It might help improve nasal airflow in patients with
nasal obstruction (Almuzian et al., 2016). RME
seems to be associated with increasing the nasal cav-
ity volume in short and long-term fields(Buck et al.,
2017). According to a systematic review, RME im-
proves nasal airflow, but it should not be used solely
for this purpose (Gordon et al., 2009). A systematic
review showed improvement in nasal breathing is
stable for 11 months post-treatment (Baratieri et al.,
2011).
• As a treatment modality for those with conduc-
tive hearing loss due to eustachian tube stenosis or
middle ear problems, low to moderate level evidence
indicates an improvement in hearing after maxillary
expansion in children and adolescents with hearing
impairments (Fagundes et al., 2017).
• Early correction of a posterior crossbite with func-
tional displacement can prevent asymmetric growth
and condyle position (English et al., 2014).
Contraindications and limitations of conventional RME
These include:
• Uncooperative patient
• Adult patient
• High angle & openbite tendency
• Convex profile
• Severely buccally tipped teeth
• In a periodontally weak dentition.
• Significant true skeletal asymmetry
• Significant expansion required
Potential complications of RME
These include:
• Pain and soreness: according to a randomised clini-
cal trial, most treated patients experience pain and
distress in terms of pressure sensation whilst actively
expanding (Halicioglu et al., 2012).
• Periodontal damage: There can be transient pulpal
and periodontal damage, as well as minimal loss of
alveolar bone support (Almuzian et al., 2016). A sys-
tematic review found significant loss of buccal bone
thickness and marginal bone level in anchored teeth
following RME (Lo Giudice et al., 2018).
• Root resorption (RR): According to a systematic
review, there is significant RR with the jack-screw
based expander (Odenrick et al., 1991) (Forst et al.,
2014). Greater RR was found to occur after tooth-
tissue-borne expansion compared with bone-borne
expansion. Most RR happened at the root’s apical
and middle thirds, with more present on the buccal
than the lingual surface (Yildirim and Akin, 2019).
• Vertical dimension changes: RME results in an in-
crease in the maxillo-mandibular plane angle and an
increase in the lower face height, which can be detri-
mental in anterior open bite cases (Jacobson, 1991).
• Scissor bite is excessive over-correction.
• Transient but rare complications such as pain, dis-
comfort, temporary diplopia, pressure necrosis of
palatal mucosa and inability to activate the appliance
Mid-palatal suture assessment methods
As described in the principle of expansion section, RME de-
pends on the palatal shelves’ separation. Growth and devel-
opment can influence this process; therefore, measures of as-
sessment of the mid-palatal suture have been proposed:
Mid-palatal suture maturation classification
A CBCT assessment in which the mid-palatal maturation
staging is divided into 5 stages (Angelieri et al., 2013):
• Stage A: The suture is seen as a relatively straight ra-
diopaque line.
• Stage B: The suture appears as a sinuous line of high
density.
• Stage C: There are 2 radiopaque, winding, and paral-
lel lines separated by areas of low radiographic den-
sity.
• Stage D: The palatine bones become more radi-
opaque, and the suture is not seen in this area. It is
still possible to observe the two parallel radiopaque
lines in the palatal area.
• Stage E: The sutures along the maxillary and pala-
tine bones are not seen, indicating suture fusion.
Interpretation mid-palatal suture maturation classifica-
tion:
• Stages A and B offer less resistance to RME; more
skeletal effects can be achieved.
• Stage C is a critical stage as suture fusion is immi-
nent, and at this stage, fewer skeletal effects are at-
tained than earlier stages, with greater dento-alveo-
lar effects.
• Stage D and E - suture fusion has occurred, and the
response to conventional RME is only dent-alveolar.

148
Assessment of mid-palatal suture maturation has the advan-
tage of avoiding complications related to maxillary expan-
sion. Also, unnecessary SARPE procedures can be avoided.
Mid-palatal suture density ratio (Grunheid et al., 2017)
A CBCT assessment can determine the suture density ratio
through the following terms and equations: The average gray
density (GDs) value is determined for a region of the suture
(GDsp) and the palatal process of the maxilla (GDppm).
The defined region of the suture is always determined on the
most central axial slice through the hard palate. The following
equation uses the average gray density values to calculate the
mid-palatal suture density (MPSD) ratio.
MPSD ratio = GDs - GDsp
GDppm - GDsp
This ratio ranges from 0 to 1, with lower values indicating
that the suture region is closer density to the soft palate and
less calcified, while values close to 1 indicate increased den-
sity and suture fusion.
Protocols of maxillary expansion
1. Conventional Rapid Expansion
Expansion is usually undertaken at a rate of 0.5-1mm (2 to 4
turns) per day. One quarter-turn of the screw yields 0.25 mm
of expansion. 16.6-34.8 pounds (7.54 to 15.8 kg) of pressure
is produced by each ¼ turn activation, which depends on the
design of the screw (Zimring and Isaacson, 1965).
During active expansion, there is an appearance of a transient
upper midline diastema. After active expansion, trans-septal
fibres between the upper central incisors recoil, resulting in
re-approximation of the central incisors. The space created
in the mid-palatal suture region is filled with haemorrhages,
causing the expansion to be unstable initially. As the resolu-
tion of the site occurs, a bony infill takes place into the site,
increasing the stability. A period of 3-4 months of retention
is required for stability, during which bony infill matures suf-
ficiently to resist relapse.
Teeth movement accompanies active expansion. Conven-
tional expansion protocols include:
• Timms protocol: For patients up to 15 years of age,
1/4 turn in the morning and ¼ turn in the evening.
In patients over 15 years, Timms recommended a
1/4 turn activation 4 times a day.
• Isaacson protocol: In growing young patients, it is
recommended to provide 1/4 turns twice a day for
4-5 days and later, a ¼ turn per day until the desired
expansion is achieved. In cases of non-growing adult
patients, it is recommended to provide a ¼ turn in
the morning, and one in the evening each day for
the first two days, then a 1/4 turn per day for the next
5- 7 days and a 1/4 turn every alternate day until the
desired expansion is achieved.
2. Semi-rapid expansion
The screw appliance is activated twice daily during the first
5-6 days followed by 3 activations per week (Işeri and Ozsoy,
2004) or a ¼ turn daily.
3. Slow Expansion
The screw appliance is activated at a rate of 1 mm per week,
one quarter turn activation every alternate day. No midline
diastema appears during slow expansion, and the ratio of
dental to skeletal expansion is approximately 4:1 with mini-
mal tissue damage.
Slow maxillary expansion produces 2-4 pounds of force,
significantly lighter than the force generated during a rapid
maxillary expansion (10-20 pounds). The whole active ex-
pansion period might take 2-5 months.
It has been claimed that the slow expansion technique is as-
sociated with a more physiologic adjustment to the maxillary
expansion, producing greater stability and less relapse po-
tential than in rapid expansion procedures. According to a
meta-analysis comparing the effectiveness of RME and slow
palatal expansion, it has been concluded that both methods
are effective at achieving expansion, with slow palatal expan-
sion being more effective overall and more so in the molar
region (Zhou et al., 2014). According to a randomised control
trial, RME can cause significantly more expansion in the area
measured at the pterygoid processes. However, for the rest
of the anatomical areas, it is not superior to the slow palatal
expansion (Martina et al., 2012). According to a randomised
control trial, RME causes more discomfort and pain than
slow maxillary expansion (Martina et al., 2012).
4. Alternate Rapid Maxillary Expansion and Constriction
(Alt-RAMEC)
Liou and Tsai developed a protocol of maxillary protraction
in 2005 to loosen the circum-maxillary sutures (Liou and
Tsai, 2005).
Modern designs of RME/ Mini-implant assisted rapid pal-
atal expansion (MARPE)
MARPE was first proposed by (Lee et al, 2010) in which the
mini-implants can be placed in the maxilla to serve as tem-
porary skeletal attachments, and the force is applied directly
to the maxillary bone. MARPE can expand the maxilla with
minimal dental effects, resulting in predominantly skeletal
changes.
A randomised control trial comparing tooth and bone borne
expansion concluded that tooth-borne expansion produced
more expansion in the premolar area only; for the remain-
ing sites of the maxilla, transverse changes are similar in both
types of devices (Lagravere et al., 2010).Types of MARPE are
(Oh et al., 2019):

a) Bone-anchored maxillary expander (BAME)
b) Tooth-bone anchored expander or maxillary skeletal ex-
pansion (MSE): MSE appliances can be used if the permanent
posterior teeth are missing or in the case of a compromised
dentition. It also shortens the treatment time and allows si-
multaneous bonding of the teeth. MSE appliances with a
semi-rapid palatal expansion protocol are indicated for grow-
ing children as their palatal bone exhibits less resistance than
adults (Oh et al., 2019).
Surgical maxillary expansion
These include:
1. Surgically assisted RME (SARME or SARPE)
The surgically assisted rapid palatal expansion (SARME)
concept was introduced in 1938 (Zong et al., 2019). This is
the main treatment modality for adult patients with maxillary
transverse discrepancy. The main resistance to the maxillary
skeletal expansion comes from buttressing the zygomatic and
sphenoid bones (pterygoid area) at their point of attachment
to the maxilla and from the mid-palatal suture once again
fused. With SARPE, these attachment points are surgically
disarticulated to allow expansion to be easily achieved using
a conventional rapid maxillary expansion appliance.
SARPE is a type of distraction osteogenesis, in which the ex-
pander is placed with a modified LeFort I osteotomy being
performed during surgery under general anaesthesia; this
enables widening of the maxilla against soft tissue resistance
only.
The main advantage of SARPE is the predictable skeletal and
dental changes with a low rate of relapse (5% - 25%) (Baccetti
et al., 2001). The main disadvantage of SARPE is the invasive
nature of the procedure, surgical risks and cost of the sur-
gical process. SARPE exhibits some relapse; therefore, over-
correction is generally unnecessary. A less invasive SARPE
approach has been proposed involving a zygomatic buttress
osteotomy under local anaesthesia.
Indications for SARPE
These include:
• There is a need for expansion after evident mid-pal-
atal suture closure in the adult’ (Alpern and Yurosko,
1987).
• Adults with more than 8 mm of transverse discrep-
ancy (Southard et al., 2019).
• When the significant maxillary expansion is re-
quired.
• SARPE is chosen when significant maxillary inter-
canine width widening is required (e.g. in patients
with significant maxillary arch anterior narrow ta-
pering).
• SARPE is used in cases of low palatal vault (where
palatal tissue can only be minimally stretched).
Complications during SARPE
These include:
• Infection and pain.
• Hemorrhage (Suri and Taneja, 2008).
• Gingival recession (Carmen et al., 2000).
• Increased chances of root resorption (Vardimon et
al., 1993).
• Injury to the branches of the maxillary nerve (Öz-
türk et al., 2003).
• Devitalization of teeth and reduced pulpal blood
flow.
• Periodontal breakdown (Cureton and Cuenin,
1999).
• Extrusion of teeth due to the attachment of the ap-
pliance (Suri and Taneja, 2008).
2. Multiple piece maxillary osteotomy (MPMO)
MPMO is chosen when along with expansion, the maxilla is
needed to be moved in other directions (for example, impac-
tion, down-graft, advancement, setback). The limit of expan-
sion with MPMO is 8-10mm, due to soft tissue stretch / re-
sistance. Depending on the height of the palate, MPMO can
be considered in cases of a high palatal vault where soft tissue
stretch may be less limiting.
MPMO is chosen in patients with a significant vertical step in
the anterior dentition, where 2 planes are present, which can
be levelled surgically.
Research indicates that levelling an anterior step up to 2mm
is stable, but research is lacking for leveling anterior occlu-
sal steps greater than 2 mm. Before MPMO, the orthodontist
should remove transverse compensations (upright posterior
teeth). Minimum segments should be planned during sur-
gery as more segments can alter blood supply and stability.
Retention and stability secondary to MPMO
These include:
• A fixed occlusal splint can be placed at the surgery
to hold the transverse correction for six weeks post-
surgically.
• After removing the splint, a TPA or a heavy overlay
wire is used to hold the transverse correction during
the remaining course of orthodontic treatment.
• Alternatively, a rigid stainless steel archwire can be
placed in surgery to stabilise the segments.
• The relapse rate is lower compared with other tech-

150
niques and varies from 5-25% (Suri and Taneja,
2008).
• Crossbite correction is stable after a follow up of 6.4
years, and a decrease in the transverse dimension is
most evident during the first 3 years after the treat-
ment (Magnusson et al., 2008).
Factors & Yardsticks
The factors & Yardsticks that determine the type and tech-
nique of expansion include:
• Age
• Aetiology
• Buccolingual inclination of the posterior teeth
• Overbite and overjet
• Buccal gingivae thickness
• The clinical condition of the teeth
• Intermolar width measurement
Appliances for unilateral maxillary expansion
Some patients do have true unilateral crossbites due to unilat-
eral maxillary constriction of the upper arch. The ideal treat-
ment is to move selected teeth on the constricted side in these
cases.
To a limited extent, this goal can be achieved by using:
• Different length arms of the W-arch or Quadhelix
• URA with asymmetric sectioning of the acrylic plate
• An alternative is to use a mandibular lingual arch to
stabilise the lower teeth and attach cross elastics to
the maxillary teeth at fault.
• TAD’s can hold the unaffected side and allow the
conventional expansion technique to work on the
affected side.
Treatment of scissor bite
These include:
• Mild to moderate cases: In a child, a functional ap-
pliance can be used to correct this relationship by
advancing the mandible forward. This may help cor-
rect the lingual crossbite. In adults, fixed appliances
can be used with cross-elastics and an expanded
mandibular archwire, buccal crown torquing of the
lower posterior teeth or an expanded archwire.
• Severe cases: If there is a skeletal Class II base re-
lationship, mandibular advancement surgery may
help correct the lingual crossbite. Surgical tech-
niques using distraction osteogenesis for widening
the mandibular arch or constriction of the maxillary
arch have also been described.
Stability and retention of expansion
It has been documented that up to 40% relapse has been
found for all three forms of active expansion (Quad-helix,
URA expansion plates, or rapid maxillary expansion), and
there is no difference between them (Herold, 1989). A meta-
analysis showed only 2.4 mm of expansion remaining after
more than a year, which was no more significant than what
has been documented as normal growth. There is insufficient
data to conclude that any useful expansion beyond expected
through normal growth was retained (Schiffman and Tuncay,
2001). Therefore, it is advisable to:
• Use TPA after SARME
• Overexpand
• Stop the cause (habit or mouth breathing)
• Achieve good buccal segment intercuspation
• Use fixed retainers or a removable one with a rigid
acrylic baseplate
• A systematic review reported that at least 6 months
of retention time should be given for all fixed or re-
movable appliances to correct a maxillary posterior
crossbite (Costa et al., 2017).
Anterior crossbites
The prevalence of anterior crossbites is 0.8% in the perma-
nent dentition (Brunelle et al., 1996). The primary treatment
modalities of anterior crossbites are:
• For dentoalveolar or mild skeletal changes, a chin-
cap or Frankel 3 (Functional) can be used
• Bodily movement using fixed 2x4 appliance
• Simple tipping movement using URA with posterior
capping, Z spring, double cantilever spring, crossed
cantilever spring, screw plate.
An RCT by Wiedel and Bondemark 2014 showed that either
fixed or removable appliance therapy could successfully cor-
rect anterior crossbite with the functional shift in the mixed
dentition from a short-term perspective (Wiedel and Bond-
emark, 2015a). Wiedel and Bondemark followed their cases
and found no difference in terms of stability between fixed
and removable appliances (Wiedel and Bondemark, 2015b).
The same research team undertook another study using the
same sample and found that the cost-effectiveness of a URA
is poorer than a fixed appliance (Wiedel et al., 2016). An-
other paper by the same group using the same sample found
that both appliances were low to moderate in terms of pain
and discomfort (Wiedel and Bondemark, 2016).
Requirement for the successful results using URA
These include:

• Cooperative patient
• Retroclined or uprighted incisors
• Adequate space
• Deep or average overbite
• Relatively aligned lower labial segment
Exam night review
Types of maxillary skeletal deficiency
• Relative maxillary deficiency: maxilla = normal,
mandible = comparatively large.
• Real maxillary deficiency: maxilla = small. Rela-
tive transverse discrepancy: In centric relation =
posterior crossbite, but if study models placed in
Class 1 occlusion = no posterior crossbite.
• Absolute transverse discrepancy: If study models
Class 1 = posterior crossbite still present.
Incidence
• Transverse maxillary deficiency 8-22% (Andrade et
al., 2009).
• Posterior crossbite 7.7%,
• Anterior crossbite 10 % (Allen et al., 2003, O’Brien,
1994).
• Functional mandibular displacement 80-97% (Thi-
lander et al., 1984).
Aetiology
• Hereditary
• Over-retained or an early loss of deciduous teeth
• Abnormal tooth anatomy
• Premature contact leading to mandibular functional
shift
• Arch length discrepancy and crowding
• Habits such as thumb sucking
• Obstruction of the upper airway due to the enlarged
adenoids
• Nasal allergies
• Mouth breathing during growing years
• Small maxilla
• Cleft lip and palate
• Iatrogenic causes, for example surgical correction of
the cleft lip and palate
Clinical Features
• Maxillary teeth can be crowded.
• Unilateral or bilateral crossbite with or without
functional jaw displacement.
• Buccally flared upper posterior teeth.
• The lingual cusps of the lower posterior teeth are
tipped inferior to the occlusal plane.
• Wide buccal corridors.
• Narrow and high palatal vault (Proffit et al., 2006).
• V or triangular shaped upper arch form.
• Impacted teeth due to constricted anterior maxilla
(McConnell et al., 1996).
Advantages of quad helix
• Optimum retention.
• No compliance needed.
• Good range.
• Can rotate molars.
• Can be used as a habit breaker.
• Orthopedic effect with differential expansion.
Disadvantages
• Little orthopedic change.
• Cause tipping of molars.
• Has a bite opening effect.
Expansion Arch (McNally et al., 2005)
• Proposed by Angle 1887, round stainless-steel wire
(1.135 mm), curved into the shape of a dental arch
• Inserted into the headgear tubes.
• Positioned over the main appliance
Rapid Maxillary Expansion RME
• Banded; tooth-borne (HYRAX/ Biedermann and
Isaacson appliances) or tooth and tissue borne (Haas
and Derichsweiler appliances)
• Bonded appliance i.e. mostly tooth-tissue borne.
• Hybrid HYRAX, Tooth and bone-borne with TADS.
Proposed indications for RME
• Crossbite correction (unilateral or bilateral).
• Correction of a functional mandibular displace-
ment.

152
• Broadening the smile (Moore et al., 2005).
• In a ‘V-shaped’ arch form due to para-functional
habits.
• Following Class 2 growth modification to correct
the relative crossbite.
• To facilitate maxillary protraction with PFM.
• Facilitating the eruption of impacted canines or in-
cisors (Baccetti et al., 2011, Pavoni et al., 2013).
• Spontaneous sagittal improvement of Class II (Guest
et al., 2010).
• Preparation for AGB in cleft patients (Shaw and
Semb, 1990).
• Space creation: 1mm of inter-molar expansion =
0.6mm relief of crowding, and 0.3mm of overjet re-
duction (O’Higgins and Lee, 2000).
• Expansion to accommodate distalised upper mo-
lars.
• Improved nasal airflow in patients with nasal ob-
struction (Almuzian et al., 2016).
• Improve hearing in patients with conductive hear-
ing loss
• Nocturnal enuresis (NE).
Potential complications of RME
• Pain and soreness.
• Periodontal damage.
• Root resorption (OIRR).
• Vertical dimension changes.
• Occurrence of scissor bite in case of over-correction.
Protocols of maxillary expansion
Conventional Rapid Expansion
• Activate 2-4 times per day = 0.5-1mm per day (0.25
per activation)
• During RME →transient midline diastema. Sepa-
rates in a pyramidal manner. 3-4 months is required
for retention and stability.
Semi-rapid expansion
• Activated 2 times per day for 5 – 6 days followed by
3 times per week.
Hybrid expansion
• Activation tapers, day 1 = 4 times activation, day 2 =
2 times activation, day 3 = 1 activation. Followed by
2 activations per week (Perillo et al, 2014).
Slow Expansion
• Activation of 1 time per week. No mid-line diaste-
ma. Ratio of skeletal to dental expansion is approx
1:4
Modern designs of RME/ Mini-implant supported palatal
expansion (MARPE)
• Bone-anchored maxillary expander (BAME)
• Tooth-bone anchored expander (MSE) Hybrid ex-
panders.
Indication of SARME (Southard et al., 2019)
• Adults with more than 5 mm transverse discrepan-
cy.
• Requirement of soft tissue changes: soft tissues also
expand with a SARPE (histogenesis).
• Need for expansion after evident mid-palatal suture
closure.
• SARME is chosen when only transverse widening
is needed, with significant maxillary inter-canine
width widening.
• Cases of low palatal vault (where palatal tissue can
only be minimally stretched).
Complications during SARME
• Significant hemorrhage (Suri and Taneja, 2008)
• Gingival recession (Carmen et al., 2000)
• Increased chances of root resorption (Vardimon et
al., 1993)
• Injury to the branches of the maxillary nerve (Öz-
türk et al., 2003)
• Infection
• Pain
• Devitalization of teeth and reduced pulpal blood
flow
• Periodontal breakdown (Cureton and Cuenin, 1999)
• Extrusion of teeth due to the attachment of the ap-
pliance (Suri and Taneja, 2008)

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16
1. Prevalence of dental & skeletal asymmetries
2. Aetiology of dental & skeletal asymmetries
3. Classification of dental & skeletal asymme
tries
4. Traumatic asymmetry
5. Management of condylar fractures in chil
dren
6. Hemifacial microsomia (HFM)
7. Clinical features of HFM
8. Types of HFM
9. Classification of HFM
10. Juvenile Rheumatoid Arthritis (JRA)
11. Treatment of Juvenile Rheumatoid Arthritis
12. Idiopathic condylar resorption (ICR)
13. Torticollis (Wry Neck)
14. Hemifacial hypertrophy
15. Hemifacial atrophy (Parry-Romberg syn
drome)
16. Asymmetric mandibular excess
17. Management of asymmetric mandibular
excess
18. Mandibular displacements on closure
19. Dental asymmetries
20. Causes of dental midline asymmetry
21. Class II subdivision
22. Class III subdivisions
23. Examination of asymmetry
24. Management of functional asymmetry
25. Management of skeletal asymmetry
In this Chapter
Dental & Skeletal
Asymmetries
Written by: Mohammed Almuzian, Haris Khan, Eesha Najam

Asymmetries
158
Asymmetry is defined as an absence of conformity in size,
shape and relative position of parts on either side of a divid-
ing line or median plane or about a centre or an axis. Facial
asymmetry is defined as an imbalance between the left and
right sides of the face (Chia et al., 2008). At the same time,
dental asymmetry represents dental midline discrepancy
from the facial midline.
Prevalence of dental & skeletal asymmetries
Amongst orthodontic patients, 12% had facial asymme-
tries and 21% dental asymmetries. The most common
asymmetry was mandibular midline deviation (62%),
followed by non-coincident dental midlines (46%), max-
illary midline deviation from the facial midline (39%),
molar classification asymmetry (22%), maxillary occlu-
sal asymmetry (20%), mandibular occlusal asymmetry
(18%), facial asymmetry (6%), chin deviation (4%), and
nose deviation (3%) (Sheats, 1998).
Most people have an asymmetry in the face and dentition,
but it is usually sub-clinical (Shah and Joshi, 1978) with
no gender difference was noted (Melnik, 1991); however,
the right side of the face is commonly larger than the left
side (Peck et al., 1991). The clinical threshold for skeletal
asymmetry was close to 5mm (McAvinchey et al., 2014).
Regarding dental asymmetry, 56% of laypersons and 83%
of orthodontists can recognize a 2mm dental asymme-
try (Burden 1999). A systematic review found up to 2.2
mm of midline deviation is considered acceptable (Jan-
son 2011). A cant of 10º or greater was considered unac-
ceptable by 70% of orthodontists and 40% of laypeople
(Thomas 2008).
Growing children between the age of 7 to 16 may mani-
fest mandibular asymmetry, and history of trauma was
found in only 14% of patients with asymmetry. The dis-
crepancy can appear to reduce for some patients due to
bony remodelling and soft tissue camouflage (Melnik,
1992, Liukkonen et al., 2005). 26% of orthognathic pa-
tients present with facial asymmetry (Proffit, 1996),
mainly class III (40%) followed by Class II orthognathic
cases (25%). The mandible and the dentoalveolar region
exhibited the greatest degree of asymmetry. This is be-
cause the growth of the mandible exhibits the longest pe-
riod of growth and 90% of mandibular deviations are to
the left. Chin deviation affects 80% of orthognathic cases,
and overall, 60% had an asymmetry in the lower face. The
midface (primarily the nose) also was affected in about
30% of the asymmetric patients.
Aetiology of dental & skeletal asymmetries
These include:
• Environmental factors such as intra-uterine pres-
sure and moulding, habits e.g. thumb sucking and
condylar hypoplasia/ hyperplasia
• Developmental factors (Chia et al., 2008) such as
Hemimandibular elongation/ hyperplasia, Condy-
lar hypo- or hyperplasia, Hemifacial macrosomia,
Hemifacial hypertrophy, Hemifacial atrophy (Parry-
Romberg syndrome), Achondroplasia, Torticollis,
Unilateral cleft lip and palate and Childhood frac-
tures of the jaw.
• Pathological factors such as Tumors of the head and
neck region ( Ameloblastoma arising in body and ra-
mus of mandible, tumours of condylar head includ-
ing osteoma, osteochondroma, chondrosarcoma),
cysts (Dentigerous cysts, keratocysts, lymphoepi-
thelial cysts), Fibrous dysplasia, Infection (Dento-
alveolar abscesses, acute parotitis), Decreased tonic
muscular activity (muscle weakness syndromes such
as cerebral palsy, muscular dystrophy), Muscular
atrophy due to impaired motor nerves and condy-
lar resorption due to juvenile rheumatoid arthritis,
post-steroid therapy and following orthognathic
surgery.
• Traumatic factors including condylar fractures and
subsequent ankylosis, which results in an asymme-
try of the jaw (Proffit et al., 1980).
• Functional factors include the functional shift from
centric occlusion to centric relation (CO-CR), lead-
ing to mandibular displacement and asymmetry in
growth. This is primarily due to constricted maxilla
or premature contacts.
• Idiopathic and iatrogenic factors such as idiopathic
condylar resorption and improper orthodontic or
orthognathic planning and treatment
• Local factors such as retained/ missing teeth or pre-
mature loss of primary teeth
Classification of dental & skeletal asymmetries
These include:
• Skeletal asymmetry mainly affects maxillary, man-
dibular basal bone or their combination (Bishara et
al., 1994).
• Dental asymmetry due to retained or missing teeth
or habits e.g. Thumb-sucking
• Muscular asymmetry, including any craniofacial
muscle hypertrophy or atrophy such as cerebral pal-
sy.
• Functional asymmetry secondary to TMJ dysfunc-
tion or a CO-CR shift.
Overview of different types of asymmetry

Asymmetries 159
Traumatic asymmetry
Condylar fractures are mostly unilateral, with 75% of chil-
dren having normal mandibular growth without the devel-
opment of an asymmetry. Moreover, most condylar fractures
remain undiagnosed (Proffit et al., 1980).
Management of condylar fractures in children
These include:
• Immobilization followed by early mobilization.
• Hybrid functional appliance: The aim of growth
modification in asymmetry cases is to achieve more
growth on one side than the other (Turvey et al.,
2004). Hybrid functional appliances consist of sev-
eral components to achieve selective dento-alveolar
eruption, mandibular repositioning and optimal
linguofacial muscle balance, which favour growth to
compensate for asymmetric mandibular deficiencies
(Vig et al., 1986). A wax bite is taken to achieve a
symmetric jaw relationship in three planes of space.
A greater vertical opening is registered on the af-
fected side; with this, downward torque of the ramus
improve the vertical defect. The unaffected side fea-
tures a posterior bite plane to inhibit tooth eruption
and allow the deficient side to allow teeth eruption.
A lingual shield is incorporated on the affected side
to prevent the tongue from interfering with tooth
eruption. A buccal shield is incorporated on the af-
fected side to achieve transverse expansion.
• Suppose the translation of the condyle is severely re-
stricted due to post-traumatic scarring. In that case,
pre-functional surgical intervention is indicated to
remove restrictions on growth and allow translation
of the condyle, followed by hybrid functional appli-
ance therapy and regular jaw exercises.
Hemifacial microsomia (HFM)
This is a congenital disorder associated with unilateral devel-
opmental defects in the orofacial region. The proposed aeti-
ologies for HFM include:
• Defect in proliferation and migration of neural crest
cells resulting in defects of 1st and 2nd arch struc-
tures.
• Hemorrhage of the stapedial artery (Poswillo, 1973).
• Goosecoid (Gsc) - potential candidate gene for
Hemifacial microsomia (Kelberman et al., 2001).
Clinical features of HFM
These include:
• Narrowed palpebral fissures.
• Unilateral epibulbar dermoids.
• Severely malformed or absent pinna of the ear.
• Periauricular skin tags.
• Variable degrees of nerve palsy (due to the associa-
tion of specific cranial nerves with branchial arches)
• Reduction in size or flattening of facial bones due to
the reduced size of the masticatory muscles.
• Mandibular asymmetry of varying severity (unilat-
eral aplasia or hypoplasia of the mandibular ramus
and condyle).
• Cleft lip and palate, palatal and tongue muscle hy-
poplasia and velopharyngeal insufficiency occur less
commonly.
• Unilateral crossbite on the affected side and canting
of the occlusal plane.
• Disturbed tooth development on the affected side
(hypodontia is 5 times more common compared
with the average population) (Monahan et al., 2001).
Types of HFM
These include:
• Type I Hypoplastic temporomandibular joint
• Type II—hypoplastic and abnormal shape of the
mandibular ramus, condyle, and temporomandibu-
lar joint
• Type III Absence of the mandibular ramus
• Type IV Mandibular body hypoplasia
Classification of HFM
Kaban’s modified classification (Madrid et al., 2010) clas-
sified HFM according to the extent of malformation and
managemet (Table 1).
Juvenile Rheumatoid Arthritis (JRA)
It is an inflammatory disease process that affects bone and
cartilage. In JRA with one to three affected joints, the TMJ is
involved in 33% of cases, while in JRA with greater than four
affected joints, the TMJ is involved in 80% of cases (Ince et al.,
2000). Progressive destruction of condyles results in shorten-
ing of the ramus and downward and backward rotation of the
chin, which leads to chin deficiency and anterior open bite.
Condylar resorption may occur faster on one side than the
other, resulting in mandibular asymmetry in 2/3rds – 3/4ths
of affected children.

Asymmetries
160
Features Treatment approach
Grade 1 Soft tissues and mandible present,
hypoplastic temporomandibular joint
Functional appliance therapy is attempted before sur-
gery.
Grade 2a Hypoplastic and abnormal shape of the man-
dibular ramus, condyle, and temporomandibular
joint, and effects on muscles of mastication
Same approach as for grade 1
Early surgical intervention to lengthen the ramus
through distraction + / - functional appliance therapy.
Orthognathic surgery as an adult.
Grade 2b Mandibular ramus is hypoplastic and markedly
abnormal in form and location, being medial
and anterior.
Condyle is considered to be non-functional. Early sur-
gery involving costochondral graft.
Total joint replacement as an adult.
Grade 3 Complete absence of the condyle and ramus as
well as severe soft tissue defects
Same approach as for the severe grade 2
Table 1: Kaban’s modified classification of HFM
Treatment of Juvenile Rheumatoid Arthritis
These include:
• Methotrexate is the most effective agent for retard-
ing disease progression.
• Functional appliances and any surgical procedures
which affect the TMJ (e.g. orthognathic surgery or
distraction osteogenesis) should be avoided. The
application of force on the TMJ accelerates disease
processes and condylar destruction.
• Total TMJ replacement in severe cases.
• Surgical maxillary impaction might be considered
in adolescents as this results in upward and forward
rotation of the mandible, improving open bite and
chin deficiency. Relapse is expected as a shortening
of ramus continues (disease progression at the TMJ).
• Augmentation genioplasty improves facial appear-
ance and does not add extra load on the TMJ.
Idiopathic condylar resorption (ICR)
The predisposing factors for ICR are preoperative temporo-
mandibular joint dysfunction (Hwang et al., 2004), young
and female patients (due to hormonal factors) and high man-
dibular plane angle with mandibular retrusion.
Torticollis (Wry Neck)
It is a muscular disorder that affects flexion, extension, or
twisting of the neck muscles beyond their normal position.
Mandibular asymmetry arises due to twisting of the head due
to excessive muscular contraction (especially sternocleido-
mastoid muscle). In children, it is due to congenital factors
such as increased intrauterine pressure during pregnancy or
pressure during birth. In adults, it can be due to infection,
tumours or trauma. Treatment of Torticollis includes surgical
detachment of contracted muscles at an early age to release
any growth restriction on the affected side (Ferguson, 1993).
Hemifacial hypertrophy
It is hypertrophy of one side of the face, and it is mainly due
to the asymmetric distribution of neural crest cells. It is char-
acterized by overgrowth in the craniofacial structures (in-
cluding soft and hard tissues). Occlusion is also likely to be
affected.
Hemifacial atrophy (Parry-Romberg syndrome)
It is progressive atrophy of soft tissues and underlying bones
on one side of the face. More common on the left side and
in females. Clinical features of Parry-Romberg syndrome are:
• Atrophic facial changes include tissues around the
nose and nasolabial folds, which later progress to the
angle of the mouth, eyes, ears and neck (follows the
distribution of the trigeminal nerve).
• Hyperpigmentation of the skin.
• Seizures
• Facial pain
• Muscle and facial bone atrophy lead to mandibular
asymmetry.
•
Asymmetric mandibular excess
This type of asymmetry was previously called condylar hy-
perplasia. It is due to excessive unilateral growth of the man-
dible, which may affect the body, ramus and condyle. This
spectrum of asymmetry includes Hemimandibular elonga-
tion, Hemimandibular hyperplasia and hybrid type elonga-
tion (Obwegeser and Makek, 1986) (Table 2 and 3). The exact
aetiology of this malformation is unknown, but it may occur
due to the escape of growing tissues on one side from normal
regulatory control (Eslami et al., 2003). Affected individuals
are metabolically normal with normal hard and soft tissue as

Asymmetries 161
Table 2: Comparison between Hemimandibular Elongation & Hemimandibular Hyperplasia
Hemimandibular elongation Hemimandibular hyperplasia
Unilateral horizontal enlargement of mandible Unilateral three-dimensional enlargement of mandible terminat-
ing at symphysis of the affected side
Both horizontal and vertical components contribute to the abnor-
mal growth pattern.
Horizontal displacement of chin point to the unaffected
side
Chin position mostly undisturbed
Dental midline usually displaced to the unaffected side
Mandibular dental midline may coincide with chin point
but does not coincide with midfacial line
Dental midlines usually coincident
Dental centerline and chin are often undisturbed
Mandibular rami lie at the same level bilaterally Increased ramal length and hyperplasia of the lower border of the
mandible on affected side
Body of the mandible displaced inferiorly and rotated medially
Normal alveolar bone height above inferior alveolar canal
of affected side
Increased alveolar bone height above inferior alveolar canal of
affected side
No compensatory transverse canting of the maxillary oc-
clusal plane
Occlusal plane remains level No lateral open bite of buccal
segment
Transverse canting of the maxillary occlusal plane due to over-
eruption of maxillary dentition on affected side to compensate for
excessive mandibular overgrowth
A unilateral lateral open bite on affected side if dental eruption
cannot keep pace with excessive vertical mandibular growth,
especially if tongue becomes interposed
Crossbite on unaffected side
Scissor bite on affected side
A unilateral lateral open bite on affected side if dental eruption
cannot keep pace with excessive vertical mandibular growth
especially if tongue becomes interposed
Radiographic findings:
Elongation of the affected side of the mandibular body
Radiographic findings:
Increased vertical length of ascending ramus
Enlargement of condyle
Elongation and thickening of condylar neck
Rounded angle of mandible
Downward bowing of lower border of mandible on affected side
Increased height of mandibular body
Increased distance between molar roots and mandibular canal
Normal height seen on unaffected side
Excessive growth demarcated by abruptly stopping at midline of
symphysis
confirmed by histologic diagnosis. Females constitute 85% of
affected cases; the age of onset of this excessive growth dis-
order is during the mid to late teenage years, as mandibular
growth progresses and becomes noticeable after the adoles-
cent growth spurt. It may be self-limiting or a progressive
condition.
Management of asymmetric mandibular excess
In cases of progressive deformity, surgical intervention of the
overgrown condyle is indicated even in young patients. Surgi-
cal options are:
• Excision of bone at the head of the condyle followed by

Asymmetries
162
Type I Broad proliferative zone
Increased thickness of hyaline carti-
lage
Cartilage islands within the bone
Type II Patchy distribution
Reduced cartilage islands
Type III Distortion of condyle
Irregular hyaline cartilage masses ex-
tend into cancellous bone of the con-
dyle or superficial articular layer
Type IV Condyle appears burned-out
Subchondral bone plate covered by fi-
brocartilage
Proliferative layer of hyaline cartilage
absent
Table 3: Histological classification of mandibular condylar
hyperplasia (Slootweg and Müller, 1986)
• recontouring or repositioning of the bony stump
into glenoid fossa
• Removal of the condyle and condylar process fol-
lowed by reconstruction of the TMJ, either with a
costochondral junction transplant or with a free
graft (Boyne, 1989).
• For adults, total joint replacement of the TMJ can be
performed.
• If excessive growth stops spontaneously and the
condition stabilizes, jaw surgery is delayed until after
the adolescent growth spurt without involvement of
the TMJ.
Mandibular displacements on closure
It is mainly due to transverse maxillary constriction or pre-
mature contacts. Mandibular asymmetry may develop due to
the shortening of the ramal height due to growth restriction
on the side of the crossbite (Schmid et al., 1991).
Dental asymmetries
It is considered the most challenging dental malocclusion
to correct (along with overjet) (Kokich, 1993); hence, it was
given a weighting of 4 in the Peer Assessment Rating (PAR)
Index (DeGuzman et al., 1995). Dental asymmetries can oc-
cur in three planes of space.
• Yaw: Discrepancy of the dentition about a vertical
axis resulting in a dental midline asymmetry (Ack-
erman et al., 2007).
• Roll: Discrepancy in the transverse plane about a
sagittal axis is termed roll deformity and results in
cant of the occlusal plane.
• Pitch: Rotation of the dentition about a coronal axis.
Causes of dental midline asymmetry
These include:
• Early loss of teeth
• Congenitally missing teeth
• Impacted teeth
• Single or multiple tooth crossbite causing functional
mandibular shift on closure
• Inappropriate extraction in case of crowding
Class II subdivision
Subdivision refers to the Class II side. It is mostly due to distal
positioning of the lower first molar on the Class 2 side but
rarely due to the upper molar occupying a more mesial posi-
tion (Janson et al., 2001) (Alavi et al., 1988) (Rose et al., 1994).
60% of Class II subdivision asymmetries were due to a 2 mm
retrusion of the mandible on the Class II side, according to a
CBCT study (Sanders et al., 2010). Class II subdivisions and
their management is provided in table 4 (Janson et al., 2007).
Class III subdivisions
Subdivision refers to the Class III side. The treatment op-
tions are:
• In cases of crowding with a deviated maxillary mid-
line, it is advisable to extract two lower premolars
and a single upper premolar on the Class III side.
• In cases of deviation of the mandibular midline only,
it is advisable to extract only one lower premolar on
the Class III side. The benefit of extracting a single
lower tooth instead of two is the better control of the
lower midline and reduced requirement for asym-
metric elastics.
Examination of asymmetry
These include:
• Extraoral soft tissue examination includes assessing
deviations of the dorsum and tip of the nose, phil-
trum of upper lip and midpoint of the chin about the
facial midline. It also contains extraoral examination
in which mandibular asymmetry is assessed from a
frontal view, superior view (bird’s eye view) or infe-
rior view (worm’s eye view) to reveal the extent of
the deviation.
• Intraoral clinical examinations include assessing the
dental midlines relative to each other and the facial
midline and assessing the mandibular displacement

Asymmetries 163
dimensions and quantification of facial asymmetry
(Nute and Moss, 2000). Laser scans are used in plas-
tic surgery to study the facial asymmetry (O’grady
and Antonyshyn, 1999).
• Stereophotogrammetry is another non-invasive and
reproducible technique of imaging. It obtains 3D
images using multiple photographs of the same ob-
ject taken at different angles. It allows detection of
changes in facial growth and development, gauging
facial morphology and monitoring facial asymmetry
over time.
• Ionising imaging includes:
1. Panoramic radiograph that allows bilateral comparison
of the mandibular ramus and condylar shape. However, the
validity is poor due to the effect of patient positioning.
2. Posterior-anterior cephalometric radiographs allow as-
sessment of left and right hard-tissue structures and skel-
etal and dental midlines. Localisation of the asymmetry is
achieved by using a midsagittal reference plane.
3. Transcranial and transpharyngeal views of TMJ are used
Class 2, type II
subdivision
Is found in about 20% of
cases
Mandibular dental midline
coincides with the facial
midline but maxillary mid-
line is deviated
Treatment is aimed at maxillary arch
• Extraction of single maxillary premolar
• First or second premolar extracted depending on extent of crowding
and midline discrepancy
• Avoid excessive tipping of anterior teeth (mesio-distal), skewing of arch
form or overcorrection of highly visible maxillary anterior dentition
Combination
Class II subdivi-
sion
• Is found in about 20%
of cases
• Features of both types
of class 2 subdivision
malocclusion
• Some tooth size
discrepancy found in
both arches
Inter-arch mechanics aimed at correction of both arches
Types of Class 2
subdivision
Features Treatment
Class 2, type I
subdivision
Is found in about 60% of
cases.
Maxillary dental midline
coincides with the facial
midline but mandibular
midline is deviated
Treatment is aimed at mandibular arch
• Non-extraction approach includes asymmetric class 2/ class 3 elastics
or heavy anterior diagonal elastics supported by class 2 elastics.
• Extraction of three units (two upper units and one lower unit on the
unaffected side).
• Newer treatment approach includes the use of TADs or class 2 correc-
tors for protraction of the mandibular arch on Class 2 side.
Table 4: Class II subdivisions and their management
on closure. Upper and lower dental midlines should
be evaluated in centric relation and centric occlu-
sion. In mandibular deviation and if lower dental
midline coincides with the chin point, the skeletal
origin of discrepancy is most likely. In the absence of
mandibular deviation and if the lower dental mid-
line is not consistent with chin point, the dental ori-
gin of difference is most likely. Cant in the maxillary
occlusal plane should also be assessed relative to the
inter-pupillary line using tongue spatula.
• Extraoral photographs, including frontal, profile
and three-quarter profile views and the front view
of patient biting on a tongue spatula, can illustrate
transverse occlusal cant. Intraoral photographs
should also be taken in centric occlusion and centric
relation in mandibular displacement.
• Laser scanning is an applicable non-invasive proce-
dure that allows digitisation and comparison of im-
ages and records more than 60,000 points in 10 sec-
onds resulting in an accuracy of 0.5 mm (Moss et al.,
1991). It allows examination of facial growth in three

Asymmetries
164
to analyse pathology, arthritic disease, and trauma to the
TMJ.
4. Lateral cephalogram can identify vertical asymmetry in
the bilateral asymmetrical superimposition of symmetric
structures. A single ear rod is used in a natural head position
for correct orientation in a patient with an altered ear posi-
tion.
5. Computerised tomography provides the most detailed
visual aid to the skeletal morphology (Sievers et al., 2011).
Cone beam computerized tomography images and 3D recon-
structed images can help study developmental deformities
and locate the position of any bony asymmetry (White and
Pharoah, 2000).
6. Radioisotope imaging such as short-lived gamma-emit-
ting isotope (Technetium 99m) is mainly indicated in Hemi-
mandibular hyperplasia and Hemimandibular elongation
cases. It is also used for imaging bones, salivary glands and
investigation of tumour pathology (especially in the salivary
glands). However, it is associated with excess radiation expo-
sure and false-negative results (Matteson et al., 1985).
• Magnetic resonance imaging can also be used to as-
sess soft tissue asymmetry.
• Study models articulated with a facebow transfer
demonstrate the relationship of the jaws in 3 planes
of space and allow assessment of the functional oc-
clusion in asymmetry cases.
• Information obtained from CBCT/ CT scan can be
used for stereolithographic printing models of the
facial skeleton. It is useful for planning surgery in
patients with severe facial asymmetry (Sailer et al.,
1998) (Kernan and Wimsatt, 2000).
• Special investigations such as incisional/ excisional
biopsies can be prescribed to reveal the nature of
hard or soft tissue pathology (fibro-osseous lesions
or tumour-like lesions).
Management of functional asymmetry
Occlusal adjustments can be performed to eliminate prema-
ture contacts that cause mild deviations of the mandible. An
occlusal splint may be required to ‘deprogrammer’ habitual
displacements to aid diagnosis. Functional displacement
of the mandible due to a crossbite might require maxillary
expansion for correction. Maxillary expansion can be per-
formed using upper removable appliances with a midline ex-
pansion screw or fixed appliances incorporating a quad-helix,
auxiliary expansion arches or rapid maxillary expansion (Gill
et al., 2004).
Management of skeletal asymmetry
These include:
1. Orthodontic camouflage: This approach can be attempted
in cases where the skeletal asymmetry is mild or accepted,
and the atypical growth must have ceased. Dental midline
discrepancies can be camouflaged orthodontically by the fol-
lowing techniques:
• Asymmetric extraction patterns for correction.
• Asymmetric mechanics include asymmetric lace-
backs, push-pull mechanics and asymmetric use of
elastics.
• Asymmetric torque for correction of asymmetric
transverse relations.
2. Surgical treatment
• Corrective orthognathic surgery is indicated after
cessation of atypical growth. Pre-surgical orthodon-
tics involves levelling and alignment accompanied
by decompensation of arches. Correction of dental
midlines to their respective jaw (skeletal) midlines
is undertaken during the pre-surgical orthodontics,
while skeletal midlines are corrected through sur-
gery. Bilateral sagittal split osteotomy is performed
in cases of severe mandibular skeletal asymmetry. Le
Fort I osteotomy may be required to correct a trans-
verse occlusal cant which occurs due to compensa-
tory maxillary growth. Post-surgical orthodontics
consists of detailing the occlusion and achieving in-
terdigitation of the arches.
• Distraction osteogenesis (DO) is indicated in severe
asymmetric mandibular deficiency where ramus
and body require lengthening, such as severe hemi-
facial microsomia or condylar fracture at an early
age causing severe restriction of translation on the
affected side (Tehranchi and Behnia, 2000)
• Adjunctive surgical procedures such as genioplasty
are indicated where the change in the chin’s repo-
sition is required in the vertical or transverse di-
mension. This is considered a very stable procedure
(Proffit et al., 1996). Implants or bone recontouring
can be adopted to correct the asymmetric shape of
the ramus or body of the mandible. Moreover, some
might even consider non-surgical soft tissue proce-
dures such as filler and BOTOX

Asymmetries 165
Exam night review
General features
• Right side is commonly larger.
• Greater than 4mm of mandibular asymmetry is
clinically noticeable (McAvinchey et al., 2014).
• Up to 2.2 mm of dental midline discrepancy is per-
ceived as acceptable (Janson et al., 2011).
Aetiology of asymmetry
Environmental factors
• Intra-uterine pressure and moulding
• Condylar hyper/hypoplasia
• Excessive condylar growth
• Habits e.g. Thumb sucking
Developmental factors (Chia et al., 2008)
• Hemimandibular elongation
• Hemimandibular hyperplasia
• Condylar hypo- or hyperplasia
• Hemifacial microsomia
• Hemifacial hypertrophy
• Hemifacial atrophy (Parry-Romberg syndrome)
• Achondroplasia
• Torticollis
• Unilateral cleft lip and palate
• Childhood fractures of the jaw
Pathological factors
• Tumors of orofacial region (e.g. Ameloblastoma
arising in body and ramus of mandible, tumors of
condylar head including osteoma, osteochondroma,
chondrosarcoma).
• Cysts (e.g. Dentigerous cysts, keratocysts, lympho-
epithelial cysts)
• Fibrous dysplasia
• Infection (e.g. Dento-alveolar abscesses, acute par-
otitis)
• Decreased tonic muscular activity (cerebral palsy,
muscular dystrophy, Muscle weakness syndromes)
• Muscular atrophy due to damage to motor nerve
• Condylar resorption due to juvenile rheumatoid ar-
thritis, post-steroid therapy and following orthogna-
thic surgery.
Traumatic factors: Condylar fractures and subsequent an-
kyloses and eventually asymmetry of the jaws (Proffit et al.,
1980).
Functional factors: Centric occlusion to centric relation dis-
crepancies can lead to mandibular displacement on closure.
Idiopathic and iatrogenic factors
Local factors
Classification of asymmetry
• Skeletal asymmetry affecting.
• Muscular asymmetry
• Functional asymmetry secondary to TMJ dysfunc-
tion or a CO-CR shift.
• Dental asymmetry
Hemifacial microsomia (HFM)
Congenital disorder →unilateral developmental defects in
orofacial region.
Proposed Aetiologies for HFM
• Defect in proliferation and migration of neural crest
cells
• Hemorrhage of stapedial artery (Poswillo, 1973).
• Goosecoid (Gsc) - potential candidate gene for
Hemifacial microsomia (Kelberman et al., 2001).
Clinical features of HFM
• Mandibular asymmetry of varying severity.
• Reduction in size or flattening of facial bones.
• Unilateral crossbite.
• Disturbed tooth development.
• Severely malformed or absent pinna of the ear.
• Periauricular skin tags.
• Narrowed palpebral fissures.
• Unilateral epibulbar dermoids.
• Variable degrees of nerve palsy
• Cleft lip and palate, palatal and tongue muscle hypo-
plasia and velopharyngeal insufficiency→ less com-
mon.
Management of HFM
• Growth modification using the hybrid functional
appliance.
• Reconstructive surgery→severe deformity.
Juvenile Rheumatoid Arthritis

Asymmetries
166
• It is a disease process that affects bone and cartilage.
• In children with one to three affected joints, TMJ
is involved in 33% of cases, while in children with
greater than four affected joints, TMJ is involved in
80% of cases (Ince et al., 2000).
• Progressive destruction of condyles results in short-
ening of ramus and downward and backward rota-
tion of the chin, which leads to chin deficiency and
anterior open bite.
• Condylar resorption may occur faster on one side
than the other resulting in mandibular asymmetry
in two thirds to three-fourths of affected children.
Treatment of Juvenile Rheumatoid Arthritis
• TMJ replacement in severe cases.
• Functional appliances and any surgical procedure
which manipulates TMJ are not recommended.
• Augmentation genioplasty
• Surgical maxillary impaction
Condylar resorption following orthognathic surgery
Predisposing factors:
• Preoperative temporomandibular joint dysfunction
(Hwang et al., 2004).
• Young and female patients (due to hormonal fac-
tors)
• High mandibular plane angle with mandibular re-
trusion.
Asymmetric mandibular excess
• It is due to excessive unilateral growth of the man-
dible, which may affect its body, ramus and condyle.
Management of asymmetric mandibular excess
• In progressive deformity, surgical reduction/remov-
al of the affected condyle is indicated even in young
patients.
• Excision of bone at the head of the condyle followed
by recontouring or repositioning of the bony stump
into the glenoid fossa
• Removal of the condyle and condylar process fol-
lowed by reconstruction of TMJ either with a costo-
chondral junction transplant or a free graft (Boyne,
1989).
Hemifacial hypertrophy
• It is hypertrophy of one side of the face.
• It is mainly due to the asymmetric distribution of
neural crest cells.
• It is characterised by overgrowth in the craniofacial
structures (including soft and hard tissues).
• Occlusion is also likely to be affected.
Examination of asymmetry
• Extraoral clinical examination
• Intraoral clinical examinations
• Non-ionizing imaging
• Ionising imaging
• Radioisotope imaging
• Study casts
• Stereolithographic models
• Pathological special Investigations
Management of functional asymmetry
• Occlusal splint
• Occlusal adjustments
• Functional displacement of mandible due to cross-
bite requires orthodontic treatment (including max-
illary expansion) for correction.
• Maxillary expansion.
Management of skeletal asymmetry
Orthodontic camouflage: for acceptable skeletal asymmetry
• Asymmetric extraction patterns
• Asymmetric mechanics
• Asymmetric torque

Asymmetries 167
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17
1. Aetiology of high angle cases
2. Clinical features
3. Radiographical features
4. Clinical implications in treating high angle
5. Treatment considerations
In this Chapter
High Angle Cases

High Angle
170
High angle in orthodontics refers to increased vertical pro-
portions of face. In cephalometric analysis, if vertical values
are above one standard deviation, then the case is considered
high angle. Cephalometric values used to diagnose high angle
are:
• MMPA greater than 29˚.
• FMPA greater than 32˚.
• LAFH greater than 57%.
• SN-Mandibular plane greater than 36˚.
• SN-Palatal plane greater than 10˚.
• Sum of inner angles are greater than 400˚.
• Y-axis angle greater than 70˚.
• Jarabak ratio greater than 61%.
• Overbite depth indicator less than 68˚ (Fatima et al.,
2016).
Aetiology of high angle cases
High angle cases cover a number of conditions including long
face syndrome, backward growth rotations, anterior open
bite and open bite tendency. The main aetiological factors are:
• Unfavorable vertical/ backward growth pattern.
• Hereditary factors, e.g. increased tongue size and
abnormal growth pattern of mandible and maxilla.
• Thumb sucking habit, which causes an anterior open
bite along with a backward rotation of the mandible
(Ngan and Fields, 1997).
• Tongue thrust habit.
• Prolonged mouth breathing, leading to over-devel-
opment of posterior dentoalveolar height.
• Orofacial matrices malfunction due to an imbalance
between jaw posture, occlusion, eruptive forces and
head position. This imbalance leads to a downward
and backward rotation of the mandible.
Clinical features of high angle cases
These include:
• Tapered facial type.
• Increased lower anterior facial height.
• Decreased upper anterior facial height.
• Steep mandibular plane angle.
• Commonly short ramus.
• Class II skeletal relationship.
• Decreased overbite.
• Increased overjet.
Radiographical features
The main cephalometric features of high angle cases include
increased mandibular inclination in relation to anterior cra-
nial base, excessive lower facial height, small posterior facial
height and large gonial and mandibular plane angle. Other
structural features of high angle cases as per Bjork are (Ski-
eller et al., 1984)(Björk, 1969):
• Decreased inter-molar and inter-premolar angle.
• Decreased interincisal angle (acute).
• Forward inclination of the mental symphysis.
• Backward inclination of the condylar head.
• Steep curvature of the mandibular canal.
• Prominent antegonial notch.
Clinical implications in treating high angle
These include:
• High angle patients can present with a reduced
overbite or an anterior open bite which is difficult to
control.
• A steep occlusal plane in high angle cases is associ-
ated with higher anchorage demand compared with
low angle cases.
• The reduced bone quality (Johari et al., 2015) and
the reduced buccolingual alveolar bone thickness
(Lee et al., 2018) explain the poor primary stabil-
ity and high failure rate of miniscrews in high angle
cases.
• High angle cases have a marked ANB discrepancy
(Class II skeletal pattern) due to downward and
backward rotation of the mandible. Clockwise ro-
tation of the mandible increases the lower anterior
face height and lead to retroclination of the lower
incisors and subsequently lower labial segment
crowding (Betzenberger et al., 1999). Therefore, any
treatment mechanics that might cause backwards
rotation of the mandible should be avoided.
• Short roots have been observed with a reduced
crown/root ratio (Uehara et al., 2013).
These include:
• It is essential to eliminate all aetiologies before treat-
ment, for example, digit sucking.
• Minimising the use of Class II elastics and bite
opening appliances are advisable.

High Angle 171
• Posterior anchorage should be carefully planned
and reinforced.
• Minimising lower labial segment proclination is es-
sential as this might negatively affect the overbite
(Houston, 1988).
• A transpalatal arch with high pull headgear to avoid
upper molar extrusion and prevent the palatal cusps
from dropping down is recommended (Scheffler et
al., 2014, Ishida and Ono, 2017). The intrusion of
maxillary posteriors could provide satisfactory oc-
clusion if an open bite is present. Hence, miniscrew
anchorage is recommended (Wang et al., 2016).
• In growing patients, a Herbst appliance attached to
an acrylic splint, along with high pull headgear, can
successfully treat high angle Class II patients (Schia-
voni et al., 1992).
• High angle cases of skeletal origin are challenging to
treat. Therefore a combination of orthodontic treat-
ment and orthognathic surgery can be indicated
(Torgersbraten et al., 2019).
Exam night review
Cephalometric values used to diagnose high angle are:
• MMPA is greater than 29˚.
• FMPA is greater than 32˚.
• LAFH is greater than 57%.
• SN-Mandibular plane greater than 36˚.
• SN-palatal plane is greater than 10˚.
• Sum of inner angles is greater than 400˚.
• Y-axis angle greater than 70˚.
• Jarabak ratio is greater than 69%.
• Overbite depth indicator less than 68˚ (Fatima et al.,
2016).
Aetiology
• Unfavourable vertical/backward growth pattern.
• Hereditary factors.
• Thumb sucking habit.
• Tongue thrust habit.
• Prolong mouth breathing.
• Orofacial matrices malfunction.
Bjork’s seven signs of high angle cases
• Increased intermolar and interpremolar angle.
• Decreased interincisal angle (acute).
• Prominent antegonial notch.
• Backward inclination of the condylar head.
• Steep curvature of the mandibular canal.
• LLS proclination (Houston, 1988).
• Elimination of aetiology
• Minimise +ve growth rotation.
• Anchorage demands.
• Avoid extrusive mechanics on posterior teeth.
• TPA with high pull headgear
• Intrusion of maxillary posteriors →if open bite.

High Angle
172
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case. Korean J Orthod, 46, 253-65.

18
1. Aetiology of Anterior open bite (AOB)
2. Classification of AOB
3. Incidence of AOB
4. Predictors of skeletal open bite
5. Features of skeletal open bite
6. Justifications for treatment of AOB
7. Aetiology of AOB
8. Digit Sucking Habit
9. Long term effects of pacifier and dummy suck
ing habit
10. Management of digit-sucking habits
11. Types of removable habit breakers
12. Types of fixed habit breakers
13. Management of mouth breathing
14. Management of secondary tongue thrust
15. Myofunctional therapy for the treatment of AOB
16. Combined myofunctional and extraoral appli
ance combination therapy
17. Extraoral appliance for management of AOB
18. Treatment principles in the management of AOB
using fixed appliances
19. Kim mechanics
20. Modified Kim mechanics
21. Molar intrusion using skeletal anchorage
22. Treatment considerations of AOB treated with
molar intrusion
23. Rapid molar intrusion device (RMI)
24. Advantages and disadvantages of RMI
25. Repelling magnets for the treatment of OAB
26. Orthognathic option for management of skeletal
AOB
27. Factors contributing to skeletal relapse
28. Adjunctive procedures
29. Stability of AOB treatment
30. Causes of relapse
31. Retention of treated AOB cases
32. Methods for retention
33. Difficulty associated with the treatment of AOB
34. Posterior open bite
In this Chapter
Anterior open bite
Written by: Mohammed Almuzian, Haris Khan, Eesha Najam, Eesha Muneeb, Muhammad Qasim Saeed

Open Bite
174
AOB is defined as a vertical discrepancy with no contact
between anterior teeth in centric relation or lack of vertical
overlap of the upper incisors’ with the lower incisor crowns
when the posterior teeth are in occlusion (Houston et al.,
1992).
Openbite can also be described as a vertical space between
maxillary and mandibular incisors perpendicular to the
functional occlusal plane and is quantified by overbite mea-
surement from the opposing dentition with the largest verti-
cal discrepancy.
Aetiology of AOB
The aetiology can be skeletal, dental or soft tissue or a com-
bination. A severe open bite is due to a marked divergence of
skeletal planes. The range of severity varies, as it may be local-
ised, affecting only a few teeth with a below-average overbite,
an edge-to-edge occlusion, or a definite space between the
upper and lower incisors.
• Dental (functional) anterior open bite is localised
to anterior teeth in occlusion. The skeletal vertical
proportions and surrounding soft tissues are usually
normal.
• Skeletal open bite occurs when the primary aetiolo-
gy of an anterior open bite is a hyperdivergent facial
growth pattern, which is an excessive divergence of
the maxillary, occlusal, and mandibular planes about
each other and the anterior cranial base (Sassouni,
1969). It may also be referred to as apertognathia
(Naini, 2011). A skeletal open bite may be caused
either by forwarding rotation (upward tipping) of a
palatal plane or by downward tipping of the man-
dibular plane.
Classification of AOB
These include:
1. Based on aetiology: developmental or acquired (Shira,
1961)
2. Based on site (anterior or lateral) and pattern (alanting or
angulated) (Thoma, 1943)
3. Based on severity and extent of involvement, (Worms et
al., 1971) include:
• Transitional open bite – open bite that occur dur-
ing mixed dentition when the permnant incisors are
erupting.
• True open bite – open bite without any vertical over-
lap as well as no contact between between upper and
lower incisors
• Simple open bite – when the open bite is 1 mm or
greater in centric relation extending from canine to
canine but does not include premolars
• Compound open bite – when the open bite extends
from premolar to premolar but does not include mo-
lars
• Infantile open bite – open bite which includes mo-
lars
4. Based on the morphology of the skeletal pattern (Kim,
1974), which include:
• Dentoalveolar open bite – when the mandible ap-
pears to be normal
• Skeletal open bite - when the mandible appears ab-
normal
5. Based on aetiological and skeletal considerations, (Rich-
ardson, 1981) include:
• Transitional open bite
• AOB due to habits such as digit sucking
• AOB due to local pathologies such as cysts, dilacera-
tions, and ankylosis
• AOB due to skeletal pathologies (de novo open bite)
such as cleft palate, craniofacial dysostosis, cleido-
cranial dysostosis and achondroplasia
• Non-pathological skeletal group (ab initio open
bite)
• AOB due to morphology and behaviour of the
tongue and lips
6. Other classification (Rakosi and Jonas, 1993) include:
• Pseudo open bite – occurs in the presence of incisor
protrusion
• Infantile open bite - involves all teeth, including mo-
lars
• Iatrogenic open bite - occurs due to erroneous orth-
odontic treatment
Incidence of AOB
The prevalence of AOB increases to 36.3% when the ante-
rior open bite is associated with sucking habits in the mixed
dentition (Cozza et al., 2005), it ranges from 17% to 18% of
children in the mixed dentition (Cozza et al., 2005, da Silva
Filho et al., 1990, Tausche et al., 2004). AOB is more com-
mon in Africans and Africa-Caribbeans with a prevalence of
5% (Noar and Portnoy, 1991). There is a marked difference
in the prevalence of dental open bite among black and white
children in the USA, affecting approximately 16% of the black
population and only 4% of the white population (Kelly et al.,
1973). In Scotland, the incidence is 4% amongst adults (Todd
and Whitworth, 1974). In the UK, open bite affects 4% of
children by 9 years of age. However the incidence falls to 2%

Open Bite 175
by the early teenage year’s (O’BRIEN et al., 1994), indicating
a marked decrease from childhood until adolescence (Worms
et al., 1971).
Predictors of skeletal open bite
These include:
A. Bjork’s structural signs of backward/posterior man-
dibular growth rotation (Björk, 1969) such as”
• A backwards inclination of the condylar head
• The curvature of the mandibular canal is flat/straight
• Prominent antegonial notch
• The mandibular symphysis is inclined backwards
and the chin is flattened and receding.
• The interincisal, inter-premolar and intermolar an-
gles are all decreased
• The lower anterior face height is increased, and
there is an anterior open bite
• PFH: AFH ratio (Jarabak ratio) (Jarabak and Fiz-
zell, 1972, Siriwat and Jarabak, 1985): PFH to AFH
ratio of 59% to 63% was defined as a neutral range. A
ratio of 64% or more significant was defined as a low
angle case/ hypodivergent grower with a deep over-
bite. A ratio of 58% or less was described as a high
angle case/ hyperdivergent grower with a reduced
overbite
• UAFH: LAFH ratio (Nahoum, 1975, Nahoum,
1977, Nahoum et al., 1972, Nahoum, 1971): The ideal
value for this ratio is 0.82. UAFH: LAFH ratio below
0.65 indicates extreme vertical skeletal discrepancy,
characterised by long lower face height and open
bite tendency. It is considered a poor prognostic fac-
tor for conventional orthodontic treatment alone. It
generally requires surgical intervention combined
with orthodontic treatment for a successful resolu-
tion.
B. Overbite depth indicator (Kim, 1974): It is defined as
the angle of the A-B plane to the mandibular plane combined
with the angle of the palatal plane to Frankfort horizontal. If
the latter angle is positive, it is added to the former angle. If
it is negative, it is subtracted from the former angle. A value
of 68˚ or less was used to indicate open bite tendency. Ac-
cording to Dung and Smith, the overbite depth indicator was
statistically significant in the occurrence of an open bite ten-
dency during the treatment (Dung and Smith, 1988).
Features of skeletal open bite
These include:
1. Skeletal features such as:
• Increased lower anterior face height – Often related
to posterior vertical maxillary excess
• Reduced posterior face height (reduced mandibular
ramus height) -In patients with average lower ante-
rior face height, the anterior to posterior face height
ratio is increased.
• Maxilla, along with maxillary occlusal plane, tilted
down posteriorly, resulting in an anticlockwise rota-
tion of the maxilla.
• Posterior (backward, clockwise) growth rotation of
the mandible (Bjork, 1969).
• Class II tendency with retrusive mandible (Lopez-
Gavito et al., 1985)
• Sagittal mandibular excess or deficiency may be pri-
mary but present along with a skeletal anterior open
bite.
• Sagittal discrepancy can also be secondary to the
vertical skeletal growth pattern; for example a nor-
mal mandible may rotate downwards and backwards
about posterior vertical maxillary excess (class 1 ro-
tate to a class 2).
• Sometimes, enlarged adenoids
• Obtuse saddle angle (formed between the anterior
and middle cranial fossae)
• Steep anterior cranial base & shorter nasion-basion
distance (Lopez-Gavito et al., 1985)
• Divergent cephalometric planes, excessive gonial,
mandibular, and occlusal plane angles, decreased
palatal plane angle (Lopez-Gavito et al., 1985)
• Area of convergence of horizontal facial planes is
positioned in front of the occiput, toward the face,
and the planes diverge anteriorly (Sassouni, 1969,
Naini, 2011)
• Increased dentoalveolar height in the molar region
compared to incisor region due to weaker muscula-
ture in high angle cases allowing greater eruption of
upper molars. (Nielsen, 1991, Moller, 1966, Ingervall
and Thilander, 1974).
• Excessive eruption of maxillary and mandibular in-
cisors
• Bjork’s seven features of posterior growth rotation
(Björk, 1969)
• Increased lower anterior facial height and compara-
tively short posterior facial height (Sassouni and
Nanda, 1964, Enunlu, 1974) Jaraback ratio of 58% or
less (Jarabak and Fizzell, 1972, Siriwat and Jarabak,
1985)

Open Bite
176
• UAFH-LAFH ratio below 65% (Nahoum, 1975, Na-
houm, 1977, Nahoum et al., 1972, Nahoum, 1971)
• Overbite depth indicator value of 68 or less (Kim,
1974)
• Tapering face
• Long lower third of the face
• Retruded chin
• Incompetent lips (resting lip separation ≥ 4 mm)
• Inadequate lip seal (Bell, 1971)
• Narrow nose
• Narrow alar bases
• Obtuse nasolabial angle & the upper lip posterior-
ly inclined (particularly in class 2 skeletal pattern)
(Naini et al., 2015)
• Average or increased maxillary incisor exposure
about upper lip – when maxillary incisors have
reached their eruptive potential but have been un-
able to meet the opposing mandibular incisors due
to the excessive increase in lower anterior face height
• Reduced maxillary incisor display or ‘no tooth
show’ smile in extreme cases – due to the restrictive
effect of a forward, resting tongue position, result-
ing in anterior dentoalveolar vertical maxillary defi-
ciency (if there is a significant additional soft‑tissue
element to the aetiology of a skeletal anterior open
bite)
• Tongue thrust type swallowing pattern to acheive a
lip seal.
4. Extraoral features (Cangialosi, 1984) such as:
• Long face
• Lip incompetence
• Steep Frankfurt mandibular plane angle
• Marked antegonial notch
• Increased anterior face height
5. Intraoral features such as:
• Mild crowding with upright incisors (tend to exhibit
crowding in the lower arch)
• May occlude only on second molars in severe cases
• Gingival hypertrophy due to mouth breathing
• Mesial tipping of molars, resulting in rotation of the
occlusal plane (Kim, 1987)
• Maxillary, occlusal and palatal planes tilt upwards,
the mandibular occlusal plane tilted downwards
• Narrow maxilla and posterior crossbite
Justifications for treatment of AOB
These include:
• Difficulty in incising food due to a lack of anterior
occlusion,
• Speech problems such as lisping – treatment of an-
terior open bite do not guarantee an improvement of speech
(Ferguson, 1995)
• Dental and facial appearance.
Aetiology of AOB
1. Skeletal factors such as:
• Excessive increase in lower anterior face height
(usually due to posterior vertical maxillary excess),
with the incisors unable to erupt due to increased
face height, resulting in an anterior open bite.
• According to Richardson, lower anterior face height
was considerably greater in anterior open bite cases
than deep overbite (Richardson, 1967).
• Reduction in mandibular ramus height results in an
increased anterior to posterior face height ratio, a
steep mandibular plane angle, a clockwise rotation
of the mandible, and an anterior open bite leading to
a skeletal open bite.
• Unfavourable growth patterns (Bell, 1971, Nahoum,
1977): Vertical facial growth tendency is predomi-
nantly genetically determined as compared to hori-
zontal growth, but environmental influences may
result in additional changes, for example worsening
of an anterior open bite in some cases (Enlow and
Hunter, 1968).
2. Environmental factors such as:
• Inflammatory - Juvenile rheumatoid arthritis in-
volving the temporomandibular joint before the age
of 16 years can develop a severe Class II malocclu-
sion and anterior open bite due to restricted man-
dibular growth.
• Hormonal - Overproduction of growth hormone
due to a tumour in the anterior pituitary gland
causes gigantism in children and acromegaly in
adults. The patient presents with a worsening class 3
malocclusion characterised by excessive mandibular
growth and a significant anterior open bite in both
situations.
• Traumatic: Bilateral condylar fractures, especially
in a growing patient, possibly leading to temporo-

Open Bite 177
mandibular joint ankylosis (Loukota and McCann,
2003). Le Fort II and III fracture cases present gag-
ging occlusion and anterior open bite (Killey, 1983,
Killey and Banks, 1987).
• Habit such as digit sucking habit, pacifier and dum-
my sucking habit.
3. Local dental factors such as:
• Transitional physiological factors - as the permanent
incisors are erupting
• Local pathology such as supernumerary tooth –
may prevent the eruption of maxillary incisors
• Localized failure of development of anterior teeth
• Over eruption of posterior teeth
• Proclination of incisors
4. Pathological factors such as:
• Idiopathic condylar resorption after orthognathic
surgery – risk factors include a female patient with
mandibular retrognathism associated with a high
mandibular plane angle, pretreatment condylar at-
rophy, and undergoing posterior condylar displace-
ment and upward and forward rotation of the man-
dible at the time of surgery (Gill et al., 2008).
• Neuromuscular conditions such as cerebral palsy
and muscular dystrophy – where poor soft tissue
tone may contribute to posterior growth rotation of
the jaws and an appreciable anterior open bite.
• According to Gershater, there is a high incidence
(32.3%) of anterior open-bite in mentally retarded
and emotionally disturbed children where problems
in controlling the tongue at rest or in function are
experienced. (Gershater, 1972)
• Systemic conditions such as systemic lupus erythe-
matosus resulting in condylysis; cleft palate.
5. Iatrogenic factors such as:
• Poorly controlled extrusive orthodontic forces on
the posterior teeth, resulting in extrusion of upper
molars and opening of the bite anteriorly in high
angle cases.
• Use of anterior bite plane in cases with a reduced
overbite.
6. Soft tissue factors such as:
• Nasorespiratory function and head posture: Pos-
tural changes to the head due to chronic partial na-
sal airway obstruction (Solow and Tallgren, 1976),
hypertrophic nasopharyngeal tissues (adenoids,
tonsils) or enlarged lymphatic tissue (Subtelny and
Sakuda, 1964, Diamond, 1980) and excessive long
term mouth breathing can affect the facial charac-
teristics by increasing the vertical pattern of facial
growth, causing downward and backward postur-
ing of the mandible, downward positioning of the
tongue, overeruption of the posterior teeth in both
dental arches and increasing the likelihood of open
bites and crossbites. (Linder-Aronson, 1970, Linder-
Aronson, 1973, Linder-Aronson, 1983, Behlfelt et
al., 1990, Woodside et al., 1991, Linder-Aronson,
1974, Harvold et al., 1972, Ricketts, 1968, Sankey et
al., 2000, Gois et al., 2008, Melsen et al., 1987). The
facial appearance of such individuals was referred to
as ‘adenoid facies’. (Vig, 1998)
• Chronic allergic rhinitis associated with non-nu-
tritive sucking habits or bottle-feeding have been
linked to anterior open bite and a posterior crossbite
malocclusion in preschool children aged 4 to 5 years
(Vázquez-Nava et al., 2006). Studies of individuals
with obstructive sleep apnea (Kikuchi et al., 2002)
and mouth breathing (Juliano et al., 2005) have
found a distinctive cephalometric pattern, which in-
cludes long face and increased lower anterior facial
height, suggesting a hyper divergent pattern of skel-
etal open bite (Frankel and Frankel, 1983). Accord-
ing to some studies, prolonged mouth-breathing due
to tonsillar or adenoidal obstruction may be a con-
tributory factor towards malocclusion, but it is not
thought to be the main causative factor (Sandler et
al., 2011) and the effects of the mode of breathing on
facial morphology were unsupported according to
Shanker 2004 (Shanker et al., 2004). An association
between open bite, respiratory pattern, sleep respira-
tory disturbance and snoring still needs to be deter-
mined (Ali et al., 1993, Gottlieb et al., 2003, O’Brien
et al., 2004, Smedje et al., 2001)
• Masticatory muscles: A relationship between weak
musculature and a hyperdivergent growth pattern
(Proffit and Fields, 1983, Ringqvist, 1973). Mastica-
tory muscles in long face patients associated with
anterior open bite are likely to have low volume
(Rowlerson et al., 2005). The smaller muscle fibers
(shorter and thinner masseter muscles) can gener-
ate less bite force. In contrast, increasing volume of
muscle, long thick masseter muscle with larger fibres
is associated with anterior growth direction, larger
posterior face height, and deep bite in short face in-
dividuals (Proffit et al., 1983, Benington et al., 1999,
Hunt and Cunningham, 1997, Ingervall and Helki-
mo, 1978, Kiliaridis et al., 1995, Corruccini, 1984).
• Tongue size, resting position and/or activity includ-
ing:

Open Bite
178
a) Tongue size – Pathology of tongue size can co-exist with
anterior open bite malocclusion. Macroglossia (for example,
in Beckwith-Wiedmann and Down’s syndrome) or ankylo-
glossia can be due to local or systemic factors; normalisation
of tongue volume in such cases is essential (Ingervall and
Schmoker, 1990). Closure of anterior open bite is unlikely to
be stable in these cases; tongue reduction surgery may have to
be considered in cases of macroglossia, but it is uncommon,
resection of an anterior V-shaped wedge and an oval mid-
line excision from anterior to the vallate papillae (Naini et al.,
2016) described by Egyedi and Obwegeser (Egyedi, 1964) is a
more helpful technique.
b) Tongue posture: A correlation between tongue position
and anterior open bite pattern has been suggested (Straub,
1960). A forward, resting tongue position (between the inci-
sor teeth) may hinder the development of the anterior ver-
tical dentoalveolar dimension, resulting in an anterior open
bite with the incisors at a different vertical level to the pos-
terior teeth along with a reverse curve of Spee in the lower
arch. According to Proffit, the resting position of the tongue
has a much stronger influence on tooth position than any
tongue thrust, as the duration of thrusting activity would be
too short of having a significant effect (Proffit, 1978)
c) Swallowing pattern: An unusual adaptive swallowing pat-
tern (secondary/adaptive tongue thrust) – tongue is thrust
forward to maintain an anterior seal during swallowing as
an adaptive response to the presence of an anterior open bite
to prevent food/liquid/saliva escaping from the front of the
mouth (Subtelny, 1965).
d) Activity - Endogenous (primary) tongue thrust is an ex-
tremely rare condition and affects only 1% of the population.
It is usually associated with an underlying abnormality in
the neuromuscular control of the tongue and excessive cir-
cumoral contraction on swallowing (for example, in Down’s
syndrome). So the open bite is difficult to correct. There is
a high tendency to relapse after treatment since the existing
soft tissue/tongue habits will not necessarily change, despite
a change in the occlusion. The typical oral features: are (Bal-
lard, 1961):
i. Bimaxillary incisor proclination
ii. Symmetrical anterior open bite
iii. A significant portion of the tongue is constantly pres-
ent between the anterior teeth – reducing their eruption and
causing intrusion.
iv. Reverse curve of Spee in the lower arch and an accentu-
ated curve in the upper arch
v. Significant sigmatism (sibilant lisping)
vi. Usually, normal face height.
Digit Sucking Habit
Non-nutritive sucking behaviour is very common in the in-
fant (Mizrahi, 1978, Subtelny and Sakuda, 1964). The inci-
dence of digit sucking decreases from 30% at 1 year of age
to 12% at the age of 9 and only 2% by the age of 12 years
(Brenchley, 1992). Prolonged digit sucking is more common
in females (Brenchley, 1992). The severity of the resulting
malocclusion depends on the patient’s age, intensity, frequen-
cy, and duration of the habit into the permanent dentition
(Larsson, 1987).
Persistent digit-sucking (greater than 6 hours) is associated
with a significant malocclusion, and the effects are often seen
in the permanent dentition due to the continuation of the
habit. Dentoalveolar discrepancies caused by prolonged digit
sucking include asymmetrical anterior open bite, interfer-
ence with the eruption of incisors, and proclination of upper
incisors resulting in an increased overjet and retroclination
of lower incisors, narrowing of the maxillary arch along with
buccal crossbite with or without lateral mandibular displace-
ment. Thumb sucking precipitates downwards movement
of mandible resulting in separation of teeth, with 1 mm of
vertical growth posteriorly (due to over eruption of posterior
teeth) opens the bite 2 mm anteriorly (Proffit et al., 2007).
Self-correction of anterior open bite is possible if the habit
stops before 9 years of age; spontaneous correction is un-
likely if prolonged beyond the pubertal growth spurt (Lars-
son, 1987). After stopping the habit, a significant proportion
of cases improve spontaneously (Finlay and Richardson,
1995), usually during the transition from the mixed to the
permanent dentition (Ferguson, 1995). Normalisation of the
overbite can take between 3 to 5 years (Bowden, 1966), but
spontaneous correction of the transverse discrepancy is not
likely (Proffit et al., 2007)
Long term effects of pacifier and dummy sucking habit
These include:
• Dental effects are primarily observed in the decidu-
ous dentition. The majority of dummy sucking hab-
its are self-limiting, and children stop using them
before the eruption of permanent teeth & long-term
effects are negligible. The severity of anterior open
bite is related to the time of use of the pacifier (Lars-
son, 1986).
• Long term use of a pacifier may postpone the erup-
tion of incisors resulting in an open bite as well as
proclination of upper incisors, narrowing of the up-
per arch, increased muscular activity on canines and
reduced activity on molars leading to a posterior
crossbite (self-correction of posterior crossbite oc-
curs if the habit stops before 4 years of age and the
contact between upper and lower incisors is repaired
resulting in resolution of open bite). (Adair, 2003,
Cadden, 2004)

Open Bite 179
• According to a study by Larsson, after quitting the
dummy sucking habit and before the eruption of
permanent teeth, children tend to suck digits. In
contrast, children with digit sucking habits con-
tinued doing so, resulting in malocclusions in the
permanent dentition (Larsson, 1971). Therefore, a
dummy sucking habit is easier to stop than a thumb
sucking habit and children who use a dummy are
less likely to become thumb suckers. Therefore dum-
my sucking has been advocated in preference to digit
sucking according to the Guidelines for Dummy and
Digit-Sucking Habits. London: British Orthodontic
Society, 2001. According to recent evidence, using a
dummy may reduce the risk of sudden infant death
syndrome (SIDS) (Li et al., 2006).
Management of digit-sucking habits
The child must want to stop the habit; otherwise, any ap-
proach is likely to be unsuccessful (Borrie et al., 2015). A
child undergoing severe psychological trauma is unlikely to
respond to any effort toward breaking the habit, and a psy-
chologist’s input may be required. The following interven-
tions are recommended to break the habit:
1. Non-physical methods
• Explanation - Simple advice about the negative ef-
fect of the habit.
• Small tangible rewards can be offered daily for not
engaging in the habit.
• Habit reversal is categorized into five phases: Aware-
ness training, relaxation training, competing for re-
sponse training, motivation training and generalisa-
tion training.
2. Physical methods
• Reminder therapy by using a physical barrier such
as finger bandage, foul-tasting paint on nail var-
nish, thermoplastic fingerpost, cotton glove, sock, or
thumb guard
• Intra-oral appliances act as deterrent appliances;
they have been influential within 10 months and
should be used after 7 months. They must be fitted
with the full understanding and co-operation of the
child and must not compromise compliance with
any future orthodontic treatment.
Types of removable habit breakers
These include:
• Acrylic plate with an anterior bite plane and habit
loops (act as a reminder to break the habit) along
with labial bow
• Hawley retainer with or without lingual spurs
• Vestibular shield incorporating a crib
• Functional appliances
Types of fixed habit breakers
These include:
• Maxillary lingual arch with palatal crib
• Vertical crib
• Combination crib
• Hayrake appliance - spurs added to a metal crib
placed in the anterior portion of the palate.
• Bluegrass appliance (Haskell and Mink, 1991) - a
roller is positioned toward the front half of the roof
of the mouth, and patients are instructed to play
with the roller bead instead of sucking their digits.
• Modified bluegrass appliance - two rollers which
may be of two different colours
• Quadhelix – useful in children who require max-
illary expansion, and the helix also serves as a re-
minder to refrain from thumb sucking.
• Soldered W arch - serves as a reminder appliance
as well as helpful in correcting posterior crossbite
caused by thumb sucking.
Summary of evidence
• In a systematic review, (Borrie et al., 2015) reported
that orthodontic appliances (palatal arch and pala-
tal crib) and psychological interventions (including
positive and negative reinforcement) are effective at
improving sucking cessation in children compared
with no treatment. The review also concluded that
palatal crib were beneficial for the occlusion com-
pared with no treatment.
• According to Cozza (Cozza et al., 2007), quad he-
lix/crib appliance was effective in correcting dental
open bite in 85% of growing patients with thumb-
sucking habits and dentoskeletal open bites. Correc-
tion of the anterior open bite was associated with a
clinically significant improvement in maxilloman-
dibular vertical skeletal relationships.
• According to a prospective randomised controlled
trial by Leite (Leite et al., 2016), both the fixed pala-
tal crib and bonded lingual spurs are beneficial in
breaking sucking habits and maintaining appropri-
ate tongue posture, effectively treating anterior open
bite in growing patients when of digit sucking habit
aetiology. However, the fixed palatal crib is more
beneficial than removable appliances or bonded lin-
gual spurs as it increases the stability of the dentofa-
cial morphologic correction.

Open Bite
180
• According to a controlled clinical trial by (Insa-
bralde et al., 2016), both removable palatal crib and
bonded spurs associated with chin cup were effective
in improving overbite; however, high-pull chin cup
therapy alone did not give favourable effects in ante-
rior open bite patients.
• According to a systematic review by (Koletsi et al.,
2018), there was no evidence to support bonded lin-
gual spurs over banded fixed appliances to correct
anterior open bite in mixed dentition children pre-
senting with digit sucking habits.
Management of mouth breathing
Adenoidectomy or tonsillectomy should only be done for
specific medical reasons (Ng et al., 2008). Evidence showed
that surgical removal of hypertrophic tonsils or adenoids did
not correspond with changes in vertical dentofacial growth
in deciduous and mixed dentition patients and did not result
in correction of anterior open bite (Lembrechts et al., 1999,
Souki et al., 2010). On the other hand, a trial showed that ad-
enotonsillectomy improved the facial growth of children with
obstructive hypertrophy, which was more evident when as-
sociated with rapid maxillary expansion (Pereira et al., 2012).
Management of secondary tongue thrust
These include:
• Tongue guard allows spontaneous and stable correc-
tion of an anterior open bite in a patient with adap-
tive tongue thrust (Rodrigues de Almeida and Ursi,
1990). Its use must be limited to patients who have
reached puberty (Proffit and Mason, 1975); as 80%
of children who have adaptive tongue thrust and an-
terior open bite at 8 years of age show improvement
without therapy, indications are therefore of an an-
terior open bite and an adolescent of normal dental
development, aged 12 and above (Burford and Noar,
2003).
• Tongue spurs/palatal crib: Parker (Parker, 1971)
used sharpened spurs soldered to upper central inci-
sor bands to significantly improve anterior open bite
and posterior crossbite by modifying tongue pos-
ture. Huang (Huang et al., 1990) demonstrated that
palatal cribs were can change tongue posture pro-
ducing correction of an anterior open bite. Psycho-
logical problems might be encountered with spurs
and temporary speech issues and difficulty in eating.
(Haryett et al., 1970, Haryett et al., 1967). Therefore,
the clinician needs to explain the purpose of tongue
spurs before starting treatment to motivate the pa-
tient. Spurs/cribs must be worn for an additional six
months after achieving positive overbite, and they
may be carried over into the retention phase. Ac-
cording to a randomised controlled trial by (Canuto
et al., 2016), both bonded and conventional spurs
resulted in a similar increase in overbite during early
open-bite treatment. 92.5% of the children had ad-
justed to the spurs after a week or less of treatment.
Another trial (Slaviero et al., 2017) showed that both
fixed and removable palatal cribs are similarly effec-
tive for correcting anterior open bite, providing an
increase in overbite with dentoalveolar arch changes,
especially in the anterior region. A recent systematic
review with a meta-analysis by (Feres et al., 2017)
suggested that crib therapy could be regarded as an
effective treatment for anterior open bite correction
in growing patients, with an increase in overbite of
about 3 mm. In comparison with removable palatal
cribs, fixed tongue cribs resulted in greater anterior
open bite correction mainly due to greater extrusion
of maxillary incisors according to a controlled clini-
cal trial by (Torres et al., 2012). However, removable
palatal cribs promoted better inclination correction
of upper and lower incisors resulting in ideal overjet
correction through reduction.
Myofunctional therapy for the treatment of AOB
Orofacial myofunctional therapy in combination with orth-
odontic treatment is more effective in maintaining anterior
open bites than orthodontic treatment alone (Smithpeter and
Covell, 2010).
1. Muscle exercises
Different muscle training exercises described in the literature
include individual practice sessions followed by homework,
training exercise cycles and repetitions, holding of small
items (such as coins or plastic spatula), or other appliances
between the lips and lip sealing exercises (Lembrechts et al.,
1999, Erbay et al., 1995a, Das and Beena, 2009, Degan and
Puppin-Rontani, 2005, Korbmacher et al., 2004). In one study
(Parks et al., 2007), patients were instructed to clench their
teeth together as hard as possible for 15 seconds and to repeat
this process at least four times for a total of one minute; this
exercise was to be performed as often as possible throughout
the day. It was concluded that masticatory muscle exercises as
adjunctive therapy for hyperdivergent patients treated with
fixed orthodontic appliances produced greater overbite in-
creases than orthodontic treatment alone. In one randomised
controlled study (Degan and Puppin-Rontani, 2005), differ-
ent orofacial muscle training protocols used as an adjunct
to traditional counselling methods for habit elimination re-
sulted in a more normalised resting position of the tongue
in the anterior part of the hard palate. According to another
randomised controlled study (Korbmacher et al., 2004), ap-
pliance based orofacial muscle training therapy was able to
significantly alter habitual mouth breathing to nasal breath-
ing and result in normalisation of tongue thrust swallowing
pattern compared to conventional exercise-based myofunc-

Open Bite 181
tional treatment protocol. They concluded the use of an ap-
pliance was more beneficial when compared to muscle train-
ing exercises with regard to promoting patient’s awareness
and compliance.
2. Vertical holding appliance
It is a modified transpalatal arch with an acrylic pad that relies
on tongue pressure to reduce eruption of upper first molars
during growth (Wilson, 1996); however, these effects have
not been proven clinically (Wise et al., 1994, Deberardinis et
al., 2000). It can restrict further anterior bite opening result-
ing from extrusion of molars during levelling and alignment
(Deberardinis et al., 2000).
3. Passive posterior bite blocks
Bite blocks are functional appliances used to open the bite
3–4 mm beyond the rest position. This inhibits the increase
in the height of the buccal dentoalveolar processes in grow-
ing patients, preventing a downwards and backward rotation
of the mandible (Iscan and Sarisoy, 1997); and allows closure
of the anterior open bite due to differential eruption of the
labial segments which can erupt unhindered. The bite blocks
are usually set at a slightly elevated position vertically. The
stretched muscles place an intrusive force on the posterior
teeth impeding their eruption and allowing an upward and
forward autorotation of the mandible (Ngan and Fields,
1997).
It has been shown that posterior bite blocks modify the verti-
cal skeletal pattern effectively (McNamara, 1977). Modifica-
tions in their design have included spring-loaded bite blocks
and use of repelling magnets embedded in the acrylic of bite
blocks (Noar et al., 1996). Cemented magnets are twice as ef-
fective as the removable spring-loaded appliance (Kuster and
Ingervall, 1992). Using bite blocks in conjunction with a high
pull headgear may increase their effectiveness (Galletto et al.,
1990).
4. Spring-loaded bite block
It has helical springs placed both lingually and buccally in
the region between the ﬁrst premolar and the last molar. The
ends of the springs are lodged occlusally in the molar regions
of the acrylic part of the device. The upper and lower acrylic
occlusal blocks are connected by palatal and lingual wires,
which are activated to a force of 450 grams bilaterally. Pa-
tients are instructed to wear the appliance for approximately
16 hours daily (Işcan et al., 1992).
5. Functional regulator appliance (Fr. IV)
It is thought to be useful where the open bite is partly due to
faulty postural activity of the orofacial musculature (Fränkel
and Fränkel, 1983). It works by allowing vertical eruption of
upper and lower incisors, retraction of the maxillary incisors.
It can change the usual downward and backward rotation of
the mandible in patients with skeletal open bite by encourag-
ing upward and forward mandibular rotation (Erbay et al.,
1995b).
According to a comparative study by (Fränkel and Fränkel,
1983), function regulators along with lip-seal training led to a
postural balance between the forward and backward rotating
muscles, resulting in overcoming the poor postural patterns
of the orofacial musculature and re-establishment of a com-
petent lip seal, producing considerable changes in the soft
tissue profile and improvement of vertical components. Ac-
cording to a Cochrane review by Lentini-Oliveira (Lentini-
Oliveira et al., 2007), there is weak evidence that FR-4 with
lip-seal training and removable appliances with palatal cribs
combined with high-pull chin cup can correct anterior open
bite in children. The clinical trials, however included signifi-
cant potential biases; these results must be viewed with cau-
tion. According to a controlled clinical trial by (Haydar and
Enacar, 1992), the FR4 appliance was mainly effective in pro-
ducing dentoalveolar changes for open bite closure; it did not
produce any significant skeletal changes, failed to improve
the facial pattern and only camouflaged the existing vertical
problem.
6. Open bite bionator
According to a retrospective study by (Weinbach and Smith,
1992), this appliance was indicated in growing patients with
class 2 skeletal patterns, where the eruption of posterior teeth
would be undesirable, either due to a slight anterior open bite
or a divergent skeletal pattern, rather than for severe open
bite cases.
7. Modifications of twin block appliance
These include:
• The lower appliance is extended distally to the molar
region with clasps on lower first molars, and occlusal
rests on second molars to prevent their eruption; up-
per appliance may incorporate a palatal spinner to
control tongue thrust, palatal crib to keep the tongue
away from anterior teeth, tongue guard, labial bow
to retract upper incisors and midline expansion
screw to widen the upper arch to accommodate the
lower arch.
• Twin Block with the upper block designed like a
‘maxillary intrusion splint’ along with extraoral trac-
tion tubes for high pull headgear can be used to cor-
rect the anteroposterior discrepancy while control-
ling the vertical dimension if an anterior open bite is
associated with Class 2 skeletal pattern (Parkin et al.,
2001).
• Intra-oral elastics can accelerate bite closure as an
alternative to high pull extraoral traction. This rein-
forces the intrusive effect of bite blocks.
• Twin block with occlusal screws placed in the up-

Open Bite
182
per block can be used for progressive mandibular
advancement to ensure that the patient with vertical
growth pattern can maintain a protrusive position
comfortably to allow their weak muscles to adapt
more gradually to mandibular advancement. (Ge-
serick et al., 2006, Carmichael et al., 1999)
• Trimming of the upper occlusal block should be
avoided to prevent the eruption of lower molars as
vertical development is not needed / undesired, in-
stead of to continue to apply a desirable intrusive
force to the posterior teeth. (Clark, 2010)
• Thick Twin block appliance: The ramps are 5 to 8
mm thick in the premolar region, opening the bite
beyond the freeway space and increasing tension in
masseter muscle, which restricts maxillary posterior
teeth’ eruption and produces relative relative intru-
sion of the posterior aspect of the maxilla in growing
patients. This is known as the bite-block effect and
provides excellent vertical control.
Combined myofunctional and extraoral appliance combi-
nation therapy
These include:
• Combined activator-high pull headgear appliances
have been recommended to reduce vertical and sag-
ittal maxillary displacement, obtain auto-rotations,
and increase the mandible’s forward displacement in
Class 2 high-angle cases (Teuscher, 1978, Teuscher,
1986).
• Van Beek appliance is a modified Harvold activa-
tor with two arms for extraoral traction, requiring a
minimum force of 300 grams per side for 12 hours.
• Teuscher activator is similar to Van Beek, but head-
gear is attached to the posterior segment of the ac-
tivator and torque springs are positioned on upper
incisors.
• Buccal intrusion splint (BIS) is used to treat skeletal
anterior open bites by the intrusion of the upper
buccal segment teeth.
• Maxillary Intrusion Splint (MIS) consists of high
pull headgear attached to a full-coverage maxillary
occlusal splint. The palatal soft tissues have been
blocked out, so the intrusive force transmitted to the
removable appliance is transmitted directly to the
teeth and is not resisted by the vault of the palate.
According to (Caldwell et al., 1984), it resulted in
the superior and distal displacement of the maxilla,
reduction in the SNA angle, clockwise rotation of
the palatal plane, and relative intrusion of the upper
molars among patients with Class 2 Division 1 mal-
occlusion and maxillary dentoalveolar protrusion.
• Maxillary Intrusion Splint and Lower Traction Plate
(CONCORDE)
Extraoral appliance for management of AOB
1. Vertical pull chin cup.
It is used as a functional orthopaedic appliance for the treat-
ment of skeletal open bite in an attempt to limit vertical jaw
growth. It delivers a force of 450-500 g per side, with the force
vector passing 45 degrees above the occlusal plane through
the anterior and inferior region of the mandibular corpus
approximately 3 cm from the outer canthus of the eye, and
it should be used for 14-16 hours per day (Pearson, 1973).
Vertical chin cup therapy effectively reduced the mandibular
plane angle and facial height during treatment and can be a
helpful treatment procedure in some backwards-rotating pa-
tients. Mandibular autorotation was attributed to a reduction
in the ‘wedging’ effect by premolar extraction, retardation of
the eruption of posterior teeth and redirection of condylar
growth (Pearson, 1978, Pearson, 1986).
Vertical chin cup therapy resulted in some intrusion of man-
dibular molars in a group of growing patients with open bites
compared to the control group (Işcan et al., 2002). The dis-
advantages of chin cup therapy include poor compliance and
the possibility of condylar damage (Burford and Noar, 2003).
In a randomised clinical trial (Pedrin et al., 2006), it was
found that the association of high-pull chin cup therapy with
a removable appliance and palatal crib provided no positive
skeletal influence on the vertical facial pattern of patients
treated for an open bite in the mixed dentition. According to
a prospective randomised study (Torres et al., 2006), using a
removable appliance with palatal cribs associated with high
pull chin cup therapy, there were no significant differences
in the level of molar eruption or lower anterior face height,
suggesting that the vertical control expected from the chin
cup therapy did not occur. Dentoalveolar changes at the an-
terior region of the dental arches (with statistically significant
extrusion, retrusion, and lingual tipping of the maxillary and
mandibular incisors) rather than soft tissue changes were
mainly responsible for the closure of the anterior open bite in
patients treated in the mixed dentition.
2. High-pull headgear
High pull headgear can be worn 14 hours per day, delivering
500 g of force to maxillary molar teeth of growing children
with skeletal class 2 base relationship to control and limit
posterior vertical growth of maxilla, inhibit eruption of pos-
terior teeth, minimising clockwise rotation and redirecting
mandibular growth in a more anterior rather than the verti-
cal direction (Watson, 1972, Kuhn, 1968, Poulton, 1967). Its
effects are based on the assumption that overdevelopment of
the posterior maxilla is responsible for the open-bite defor-
mity (Epker and Fish, 1977). Different options available are
as follows:

Open Bite 183
• Headgear can be applied directly to the upper molar
bands of a fixed appliance - sufficient to close minor
anterior open bites.
• Headgear can be used in conjunction with a func-
tional appliance to try and correct an increased
overjet when there is a reduced overbite and a verti-
cal growth pattern.
• Headgear is used along with upper removable ap-
pliance with posterior cappings such as a maxillary
intrusion splint or buccal intrusion splint.
• High pull headgear along with transpalatal arch giv-
en in Class 2 patients to intrude upper first molars
and prevent the dropping of palatal cusps (Firouz et
al., 1992).
Treatment principles in the management of AOB using
fixed appliances
Arat (Arat and Iseri, 1992) compared the effectiveness of the
Begg technique, Edgewise technique, and functional appli-
ances for the treatment of skeletal open bite. Fixed appliance
therapy increased the upper and lower posterior dentoalveo-
lar height, marked backward rotation of the mandible, and
increased anterior facial height. Some treatment principles
are as follows:
• Banding of second molars should be avoided be-
cause they tend to extrude when engaged on the
archwire. If second molars are banded, they should
be banded or bonded with the molar tubes in the
occlusal third of the clinical crown, or the archwire
should be stepped gingivally to avoid extrusion of
the terminal molar on the appliance (Pearson, 1996).
• Any procedure that would promote an increase in
facial height or extrusion of posterior teeth must be
avoided to prevent worsening of an anterior open
bite; therefore, Class 2 and Class 3 elastics and the
distal movement of teeth using headgear are contra-
indicated (unless intrusion is also planned).
• Extraction therapy: If extractions are indicated in
high angle cases (due to caries, gross premature
contact etc.), extractions more posterior in the arch
can be helpful as it reduces the posterior face height
by the forward movement of terminal molars, caus-
ing a reduction in maxillo-mandibular plane angle
(Mizrahi, 1978) (Aras, 2002). Extraction therapy can
result in a significant increase in the lower posteri-
or face height in moderately steep cases (Pearson,
1973) & mesialization of posterior teeth following
extractions can achieve intrusion of molars (Jacob-
son, 1986). Extraction of premolars or molars has
been recommended to “close the wedge” and to re-
duce the vertical dimensions (de Freitas et al., 2004);
it may be effective in hyperdivergent cases with
moderate crowding, but it is controversial in cases
of severe open bite (Cangialosi, 1984). Molar extrac-
tions may reduce the magnitude of the open bite by
forwarding mandibular rotation. Still, it does not al-
ter the physiological rest position of the mandible,
so the total facial height remains the same (Nahoum,
1977). Similarly, other researchers believe extraction
therapy does not reduce the lower facial height of
patients with an open bite who have supra-eruption
of the lower molars. (Kim et al., 2000) (Jenner and
Fitzpatrick, 1985).
• Bracket set up: This includes reduced canine tipping
and gingival placement of the brackets of the ante-
rior teeth.
• Tongue tamer or palatal crib: According to a ran-
domised clinical study by (Leite et al., 2016), both
the fixed palatal crib and bonded lingual spurs are
simple and effective for the treatment of anterior
open bite in mixed dentition, with fixed palatal cribs
being favoured.
• Quad-helix/crib appliance: According to a con-
trolled clinical trial by (Mucedero et al., 2013), quad-
helix/crib appliance led to successful outcomes in
about 93% of the patients & correction of dentoskel-
etal open bite was associated with a clinically signifi-
cant downward rotation of the palatal plane.
• Vertical intermaxillary elastics: Vertical intermaxil-
lary elastics can be used to extrude the anterior teeth
in patients where the anterior open bite is related
to a digit-sucking habit that has prevented the inci-
sors’ eruption. Elastics are not recommended if the
aetiology is primarily skeletal because the incisors
are already maximally erupted. Any orthodontic
treatment aimed at extruding them would be aes-
thetically inappropriate and unstable. Elastic may be
combined with a transpalatal arch (TPA) and high-
pull headgear to restrict vertical development of the
maxillary molar teeth.
• Kim mechanics (Multiloop Edgewise Archwire
Technique)
Kim mechanics
This technique uses multi-loop gable-bend edgewise arch-
wires made from rectangular 0.016 × 0.022 stainless steel
archwires with a series of vertical loops bent into them for
flexibility with divergent curves of Spee (increased curve of
Spee in the maxillary arch and a reverse curve of Spee in the
mandibular arch) combined with heavy anterior elastics to
achieve molar intrusion and simultaneous incisor extrusion
to close the bite anteriorly (Kim, 1987).

Open Bite
184
Kim recommended a 0.018” slot and standard edgewise
brackets, but the use of 0.022” straight-wire appliance sys-
tems have also been used with this technique. Five L-loops
are placed on each side of the archwire, starting between the
lateral incisors and canines to the first and second molars.
The vertical dimensions of the loops should be 2-3 mm, and
the horizontal dimensions should be 5 mm except in the mo-
lar region where it is increased to 8 mm. Tip backs of 3 to
5 degrees are placed on each loop. 3/16” heavy elastics are
placed vertically between the most anterior loops in the max-
illa and mandible.
Active forces in the archwire are transferred to the posterior
buccal segments resulting in the posterior intrusion. Mesial
tipping of the molars is commonly seen in skeletal open bite
resulting in rotation of the occlusal plane; the posterior teeth
are distally uprighted using this technique by placing a flat
0.016” x 0.022” archwire once the terminal molars are out of
contact and no further reduction of the anterior open bite
occurs while continuing the anterior elastics. Distal upright-
ing of buccal dentition is facilitated by removing the terminal
molars, as this removes occlusal contacts closer to the ful-
crum of the temporomandibular joint, allowing the mandible
to hinge upward forward.
Extracting the second molars could minimise resistance to
uprighting the posterior teeth in adolescents who have well-
shaped and well-positioned third molars.
This technique minimally affects the skeletal pattern and has
limited usefulness for patients with adequate or excessive
dentoalveolar height before treatment.
Treatment changes occur mainly by a dentoalveolar compen-
sation mechanism, which causes retraction and extrusion of
the anterior teeth, alteration of the occlusal plane and distal
uprighting of posterior teeth (Küçükkeleş et al., 1999, Chang
and Moon, 1999).
Modified Kim mechanics
Nickel-titanium wires can be used rather than multi-looped
rectangular archwires, achieving similar flexibility to multi
looped stainless steel archwires and without the requirement
of bending loops (Küçükkeleş et al., 1999). The wires are
modified by placing an accentuated curve of Spee in the max-
illary arch and a reverse curve of Spee in the mandibular arch
combined with heavy anterior vertical elastics with crimpable
hooks. This effectively overcomes the extrusive forces placed
on the anterior teeth and causes their intrusion (Enacar et
al., 1996).
Molar intrusion using skeletal anchorage
These include:
• Titanium miniplates temporarily implanted in the
maxilla or mandible can provide temporary skeletal
anchorage for molar intrusion in managing the open
bite malocclusion (Umemori et al., 1999).
• Miniscrews can bring about the absolute intrusion
of posterior teeth, which may help to increase the
overbite (Kravitz et al., 2007, Cousley, 2014). Minis-
crew has been reported to provide skeletal anchorage
to intrude buccal segments in patients with hyperdi-
vergent growth patterns by reducing the posterior
dental height, resulting in autorotation of mandible
in a closing counterclockwise direction. Closure of
maxilla-mandibular plane angle and reduction of
anterior facial height occurs without the need for
surgical intervention (Park et al., 2004); this rotation
is also suggested by a systematic review which may
lead to an improvement in facial profile, especially in
hyperdivergent patients (Alsafadi et al., 2016).
• Miniscrew implants must be placed distal to the
centre of resistance of the whole dentition (premolar
region) since the resultant posterior intrusive force
produces a clockwise rotation of the maxillary den-
tition and a counterclockwise rotation of the man-
dibular dentition, which contributes to the closure
of the anterior open bite (Park et al., 2006).
• The magnitude of the mandibular autorotation after
molar intrusion depends on several factors, includ-
ing the amount of intrusive force, duration of intru-
sion, and placement of intrusive force in the upper
or lower arch. It is believed that 1 mm of intrusive
vertical movement of the molars would result in
about 2 mm closure of anterior open bite by man-
dibular counterclockwise rotation (Scheffler et al.,
2014).
• Molars can be intruded approximately 2-4 mm us-
ing skeletal anchorage, with better results in the
maxilla compared to mandible (Scheffler et al., 2014,
Deguchi et al., 2011, Baek et al., 2010, Akan et al.,
2013). This can be attributed to the thicker corti-
cal bone in mandible that may resist intrusive forces
more than the maxilla (Deguchi et al., 2011).
• Molar intrusion using TADs and elastomeric chains
attached to miniscrews can apply a force of 150–200
g per tooth on each side (Buschang et al., 2011, Xun
et al., 2007). Miniplates can apply 400 g of force per
segment for posterior tooth intrusion (Akan et al.,
2013, Erverdi et al., 2007).
Treatment considerations of AOB treated with molar in-
trusion
These include:
• Consider the skeletal relationship, including the
vertical, transverse, and sagittal relations. Skeletal
Class 1 or mild skeletal Class 2 jaw relationships

Open Bite 185
with skeletal open bite and extended anterior facial
height can be treated by the intrusion of posterior
teeth as a closing counterclockwise rotation of the
mandible occurs with a shortening of the anterior
facial height and a correction of the open bite. Ac-
cording to Sugawara 2002 (Sugawara et al., 2002),
miniscrew supported molar intrusion resulted in a
significant reduction in anterior lower facial height,
mandibular plane angle, and ANB difference along
with a significant increase in overbite and Wits ap-
praisal. In the case of skeletal Class 3 open bite, the
counterclockwise rotation caused by the intrusion
of posterior teeth worsens the Class 3 discrepancy,
despite the correction of open bite, making orthog-
nathic surgery more likely to be required.
• Consider facial esthetics such as incisor exposure
at rest and smile before starting treatment. Patients
with insufficient incisor exposure should not be
treated by the molar intrusion, as incisor extrusion
is more suitable for open bite correction. Clockwise
rotation of the whole maxillary arch can occur dur-
ing molar intrusion if the entire arch is bonded with
fixed appliances; this can be minimised with either
sectional arch mechanics or by adding an exagger-
ated curve of Spee to the maxillary archwire if extru-
sion of upper incisors is contraindicated (Park et al.,
2006, Erverdi et al., 2004).
• Careful control of the first, second, and third-order
relationships of the intruded molars is essential for
a successful outcome during the active intrusion
phase.
• The periodontal condition must be considered since
intrusive forces might affect the periodontal health
of the intruded molars. Regarding the intrusion of a
molar with periodontal disease, (Melsen et al., 1988)
reported that periodontal tissue recovers by new at-
tachment through intrusion. In contrast, Vanarsdall
(Vanarsdall, 1995) suggested extrusion rather than
intrusion for the health of the periodontal tissue as
bone deposition occurs with tension rather than
pressure. In patients with mild periodontal disease,
periodontal treatment is needed before the orth-
odontic treatment, and periodic periodontal man-
agement and radiographs should be taken during
treatment. If the periodontal condition is not suit-
able for molar intrusion, surgical intervention is re-
quired to correct open bite.
• Assessment of bone quality, local root anatomy, ac-
cessibility at insertion site. Maxillary buccal mini-
implants have been less stable in high angle cases
than normal/low angle ones, which is most likely
linked to the thinner maxillary cortical plate in long
face cases (Antoszewska et al., 2009, Miyawaki et al.,
2003). Various options for insertion sites of mini-
implants in AOB cases are available, including:
a) Buccally positioned TADs apply intrusive vertical force to
the molars and a TPA in the maxilla or a lingual arch in the
mandible to prevent distortion of the arch form and buccal
tipping of the posterior teeth. Tongue pressure on the maxil-
lary TPA may contribute to molar intrusion. It must be re-
lieved from the palatal mucosa, approximately the distance
that the molars are expected to be intruded (Sherwood, 2007).
b) For TADs located in the palate, the torque and bucco-
palatal position of the molars being intruded must be moni-
tored since it is difficult to obtain a vector sum that passes
through the centre of resistance due to the anatomy of the
palatal and buccal alveolar bone. A buccal force from another
buccal screw can be combined to counteract the palatal mo-
ment (Lee et al., 2004). Cousley performed maxillary molar
intrusion by bilateral mini-implants inserted in the palatal
alveolus and a customised TPA for both transverse arch con-
trol and the application of direct traction (Cousley, 2010). For
intrusion of a single molar tooth, the force could be applied
from a cantilever attached directly to the miniscrew in com-
bination with a TPA to counteract third-order side effects
(Uribe et al., 2013).
Rapid molar intrusion device (RMI)
RMI was first proposed by Carano (Carano and Machata,
2002) as a non-compliance option for treating anterior open
bite. It is composed of two elastic modules secured on the
first molars with L-shaped pins; the straight terminal end at-
taches into a maxillary molar tube, and the angulated termi-
nal end attaches to a mandibular tube. The flexed modules
deliver an immediate intrusive force of 800 g on each side
when the patient closes their mouth; this force level decays
to 450 g by the end of the 1st week and 250 g by the second
week. This appliance is always placed with a TPA in the upper
arch and a lingual arch in the lower arch because the intrusive
forces on the labial side of the molars generate moments that
tip the crowns buccally.
Advantages and disadvantages of RMI
These include:
• Significant intrusion of upper and lower first molars
in growing patients and adults.
• It can also intrude on the first and second molars if
attached together.
• Both the upper and lower molars are intruded si-
multaneously, so it cannot be used for the intrusion
of molars in one arch (Carano et al., 2005a, Carano
et al., 2005b).
Repelling magnets for the treatment of OAB

Open Bite
186
Active vertical corrector introduced by (Dellinger, 1986) is
a fixed or removable appliance developed for the intrusion
of posterior teeth in the maxilla and mandible by recipro-
cal forces. It consists of two posterior occlusal splints with
samarium cobalt magnets incorporated over the occlusal re-
gion of the teeth planned to be intruded, generating between
600 and 650 grams of force per module. Kalra (Kalra et al.,
1989) have suggested that magnets may be beneficial in treat-
ment anterior open bites by:
• Intruding upper and lower posterior teeth and al-
lowing mandibular autorotation in growing patients.
• Distracting the condyle downwards and forwards
allows compensatory condylar growth which would
also promote favourable mandibular autorotation.
A randomised clinical trial (Kiliaridis et al., 1990) compared
the effects of samarium cobalt repelling magnets incorpo-
rated into acrylic splints versus acrylic bite-blocks to correct
anterior open bite. Both produced a positive response in the
dental and skeletal vertical relationships in growing indi-
viduals by causing intrusion of posterior teeth with intrusive
forces generated by the masticatory muscles, resulting in a
decrease or elimination of anterior open bite.
Orthognathic option for management of skeletal AOB
Orthognathic surgery for treatment of skeletal AOB is indi-
cated in (Greenlee et al., 2011):
• Non-growing patients.
• Esthetic need.
• Severe open bite and extreme vertical measure-
ments are greater than two standard deviations from
normal.
• Skeletal problems in multiple planes of space.
Surgical options to correct skeletal AOB are (Naini and Gill,
2017):
• Le Fort 1 osteotomy with differential posterior max-
illary impaction: Rotation of the maxillary occlusal
plane around the transverse axis with differential
posterior impaction allows forward autorotation of
the mandible to close an anterior open bite. Orth-
odontic preparation requires proclination of the
maxillary incisors, as posterior surgical impaction
produces relative retroclination of the maxillary in-
cisors.
• Segmental impaction of the posterior maxilla: Verti-
cal segment of the maxilla is cut either distal to the
canines or distal to the lateral incisors following Le
Fort I osteotomy. After preoperative independent
levelling and alignment, anterior and posterior seg-
ments are moved separately. The posterior segment
is repositioned superiorly, allowing forward auto-
rotation of the mandible to close the anterior open
bite. The anterior segment is repositioned vertically
to obtain the ideal maxillary incisor exposure in re-
lation to the upper lip.
• Isolated mandibular surgery: Anterior rotation of
the distal segment of the mandible following a bi-
lateral sagittal split osteotomy may be used to close
some mild anterior open bites up to 4 mm, in the
absence of excessive inclination occlusal plane
(Bloomquist and Joondeph, 2016). According to
(Bisase et al., 2010), mandibular sagittal split oste-
otomy with rigid internal fixation was the procedure
of choice to correct anterior open bite in patients
with short mandibular ramus and normal condyles
absence of ongoing resorption and a well-positioned
maxilla (no posterior maxillary excess).
Factors contributing to skeletal relapse
Factors contributing to skeletal relapse after combined orth-
odontic and orthognathic surgical approach:
• Type of osteotomy.
• Type of skeletal fixation - rigid internal fixation pro-
vides better stability compared to intraosseous wire
techniques. (Brammer et al., 1980, Hiranaka and
Kelly, 1987, Hoppenreijs et al., 1997).
• Neuromuscular influences on the repositioned jaws
(Reyneke and Ferretti, 2007).
Adjunctive procedures
These include:
• Glossectomy - It effectiveness in closing anterior or
posterior open bite problems has not been substanti-
ated.
• Surgical procedures to improve the patency of the
airway.
• Occlusal adjustments (Janson et al., 2008).
• Corticotomy assisted molar intrusion (Akay et al.,
2009).
Stability of AOB treatment
Studies of long term results for orthodontic treatment of
open bite by (Lopez-Gavito et al., 1985) and surgically treated
cases by (Denison et al., 1989) indicate that relapse rates can
range from 35% to 42.9%. A slight increase in overbite may
occur during the post retention phase, up to 15 years after
removing appliance (Zuroff et al., 2010). Approximately 80%
of anterior open-bite subjects will maintain positive overlap
after treatment, whether with orthodontics or a combination
of orthodontic-surgical therapy (Huang, 2002).
• Predictors: Overbite depth indicator (Dung and

Open Bite 187
Smith, 1988) and the extent of an anterior open bite
(Kim, 1974) at the start of treatment were the best
predictors of success. According to a comparative
study (Lopez-Gavito et al., 1985), neither the mag-
nitude of pretreatment open bite, mandibular plane
angle, nor any other single parameter of dentofacial
form proved to be a reliable predictor of post-treat-
ment stability.
• Type of treatment: Orthodontic therapies appear
to have slightly lower treatment success but better
stability than the surgical therapy (Huang, 2002).
More than 35% of orthodontically treated open-bite
patients demonstrated a post retention open bite of
3 mm or more, according to a longitudinal study by
(Lopez-Gavito et al., 1985). According to a meta-
analysis (Greenlee et al., 2011), the stability with
both surgical and non-surgical treatment modalities
of AOB appeared to be greater than approximately
75%. According to a retrospective study by (Swin-
nen et al., 2001), open bite patients treated with Le
Fort I impaction or extrusion, with or without an ad-
ditional bilateral sagittal split osteotomy, show good
maxillary stability one year after surgery. However,
the canting of the palatal plane relapsed completely
within the first year after surgery.
• Extraction therapy: A systematic review (Medeiros
et al., 2012) showed that orthodontic treatment with
extractions seemed to be more stable than non-ex-
traction, single-jaw surgery was more stable com-
pared with bimaxillary surgery. Greater stability of
open bite correction is achieved when orthodontic
treatment is carried out with extractions compared
to non-extraction treatment (Janson et al., 2006,
Chang and Moon, 1999).
• Miniscrews: The tendency of relapse ranges between
20% and 30% when using TADs for molar intrusion
& the relapse predominantly occurs during the first
year of retention (Deguchi et al., 2011, Sugawara et
al., 2002, Baek et al., 2010, Sakai et al., 2008)
• Multiloop edgewise archwire therapy: The open bite
correction obtained by the multiloop edgewise arch-
wire therapy was very stable, with less than 0.5 mm
of relapse occurring during the 2-year follow-up pe-
riod. (Kim et al., 2000)
• Type of teeth movement: Extrusion of anterior teeth
to close an anterior open bite is considered less sta-
ble than posterior intrusive mechanics, especially
in cases with an excessive vertical height of anterior
maxilla (Ellis and McNamara, 1984). On the other
hand, a systematic review (Solano-Hernández et
al., 2013) showed that vertical relapse was seen in
several patients after combined orthodontic surgical
treatments regardless of the type of surgery. Den-
tally, relapse was observed by an opening of the bite,
which was more commonly observed after Le Fort
I osteotomy than bimaxillary surgery. Skeletally, re-
lapse was depicted by increased mandibular plane
and intermaxillary angles during long-term follow-
up, which was more commonly seen after bimaxil-
lary surgery than Le Fort I osteotomy.
Causes of relapse of treated AOB cases
These include:
• Unfavourable growth patterns such as posterior
mandibular growth rotation & continuation of max-
illary vertical growth after completion of orthodon-
tic treatment (Burford and Noar, 2003).
• Soft-tissue factors such as an unfavourable tongue
posture or size, orofacial musculature & respiratory
problems (Huang, 2002) .
• Resumption of a digit-sucking habit.
• Inappropriate orthodontic tooth movement, such
as excessive incisors extrusion when previously
reached maximum vertical eruption.
• Surgery has increased the posterior face height; for
example, if a mandibular procedure is used in isola-
tion to close an anterior open bite.
Retention of treated AOB cases
These include:
• Prolonged retention with fixed or removable retain-
ers is advisable during an active growing period.
• Intrusion or prevention of eruption of posterior
maxillary teeth should be continued until growth
ceases (Lawry et al., 1990).
• Treatment results must be maintained to prevent la-
bial flaring of the incisors (Kassir and Saade, 2017).
Methods for retention
These include:
• High-pull headgear or vertical chin cup applied to
the upper molars and a standard removable retainer.
• Retainer with passive posterior bite blocks to place
intrusive forces on posterior teeth.
• Retainers with occlusal coverage prevent further
molar eruption in patients with remaining growth.
• Continued use of open bite activator or a bionator
with bite blocks between posterior teeth.
• Daytime wrap around retainer with modified con-
tour engaging the cementoenamel junction to coun-

Open Bite
188
teract the intrusive relapse of anterior teeth, along
with a different appliance incorporating a tongue
crib for nighttime retention.
• Tongue crib or lingual spurs during or after treat-
ment may enhance stability in patients where abnor-
mal tongue posture and aberrant function have been
contributory factors (Huang et al., 1990, de Cuebas,
1997, Justus, 2001).
• Fixed modified Nance-Hyrake appliance can also
train the tongue in cases of aberrant tongue position
or function.
• Lip and tongue muscle exercises have been recom-
mended once a day, supervised by a speech and lan-
guage therapist once a week.
• Miniscrews used in the mandible can be kept longer
during the initial phase of the retention (Deguchi et
al., 2011).
• Overcorrection has been recommended to compen-
sate for any relapse after molar intrusion using TADs
(Sakai et al., 2008).
• Retainer covering the occlusal surfaces of the mo-
lars with elastics to the buccal TADs (Scheffler et al.,
2014)
Difficulty associated with the treatment of AOB
These include (Burford and Noar, 2003) (Sandler et al., 2011):
• Tendency for posterior growth rotation worsens the
Class 2 malocclusion and makes the use of function-
al appliances challenging.
• Majority of the orthodontic treatment mechanics
are extrusive in nature which worsens the open bite.
• Poor compliance to prolonged retention methods
results in poor stability.
• Maxillary extraction spaces may be lost quickly due
to:
a) Thin cortices and trabecular bone of the maxilla provide
less resistance to movement than the mandible’s thick corti-
ces and denser trabeculae.
b) Masticatory muscles provide greater restriction to pos-
terior mandibular teeth movement than posterior maxillary
teeth.
Posterior open bite
It is defined as the failure of several teeth in either or both
opposing buccal segments to reach occlusion, although there
is incisor contact. Autosomal dominant inheritance has been
reported (Bosker et al., 1978).
Causes of posterior open bite
These include:
• Interposition of the tongue between teeth, interfer-
ing with eruption
• Disturbances in eruption (for example, ankylosis)
• Primary failure of eruption - familial cases have
been reported (Brady, 1990, Ireland, 1991)
• Primary failure of alveolar process development
(Capon, 1944, Kurol, 1981)
• Trauma
• Hemimandibular hyperplasia where the vertical
compensation is insufficient
Treatment of posterior open bite
These include:
• Habit breaker in the posterior region
• Restorative correction with composite build-up or
Onlay / crown
• Orthodontic extrusion with fixed appliances or
TADs
• Segmental dentoalveolar osteotomy
• Segmental maxillary or mandibular surgery
Exam night review
Anterior open bite (AOB)
AOB is defined as a vertical discrepancy with no contact
between anterior teeth in centric relation or lack of verti-
cal overlap of the upper incisors’ incisal third of the lower
incisor crowns when the posterior teeth are in occlusion
(Houston et al., 1992).
Classification of AOB
• Based on aetiology: developmental or acquired (Shi-
ra, 1961)
• Based on site (anterior or lateral) and pattern (alant-
ing or angulated) (Thoma, 1943)
• Based on severity and extent of involvement,
(Worms et al., 1971)
• Based on the morphology of the skeletal pattern
(Kim, 1974), which include:
• Based on aetiological and skeletal considerations,
(Richardson, 1981)
Incidence of AOB
• Prevalence increases to 36.3% when the anterior
open bite is associated with sucking habits in the
mixed dentition (Cozza et al., 2005)

Open Bite 189
• AOB is more common in Africans and Africa-Ca-
ribbeans with a prevalence of 5% (Noar and Portnoy,
1991)
Bjork’s structural signs of backward/posterior mandibular
growth rotation (Björk, 1969)
• A backward inclination of the condylar head
• The curvature of the mandibular canal is flat/straight
• Prominent antegonial notch
• The mandibular symphysis is inclined backwards
and the chin is flattened and receding.
• The interincisal, inter-premolar and intermolar an-
gles are all decreased
• The lower anterior face height is increased, and
there is an anterior open bite
Aetiology of AOB
• Skeletal factors
• Environmental factors
• Local dental factors
• Pathological factors
• Iatrogenic factors
• Soft tissue factors
Management of digit-sucking habits
1. Psychological counselling
2. Non-physical methods
• Explanation
• Reward
• Habit reversal
3. Physical methods
Myofunctional therapy for the treatment of AOB
• Muscle exercises (Lembrechts et al., 1999, Erbay et
al., 1995a, Das and Beena, 2009, Degan and Puppin-
Rontani, 2005, Korbmacher et al., 2004).
• Vertical holding appliance (Wilson, 1996)
• Passive posterior bite blocks (Iscan and Sarisoy,
1997)
• Spring-loaded bite block (Işcan et al., 1992).
• Functional regulator appliance (Fr. IV) (Fränkel and
Fränkel, 1983).
• Open bite bionator (Weinbach and Smith, 1992)
• Modifications of twin block appliance
• Combined myofunctional and extraoral appliance
combination therapy
Fixed appliances
• Extraction therapy
• Bracket set up
• Wire bending to allow incisor extrusion
• Tongue tamer or palatal crib
• Quad-helix/crib appliance
• Segmented arch mechanics
• Vertical intermaxillary elastics
• Kim mechanics (Multiloop Edgewise Archwire
Technique).
• Modified Kim mechanics
• Molar intrusion with skeletal Anchorage
• Rapid Molar Intrusion device (RMI)
• Repelling Magnets
Orthognathic surgery
1. Le Fort 1 osteotomy with differential posterior maxillary
impaction
2. Segmental impaction of the posterior maxilla
3. Isolated mandibular surgery
Adjunctive procedures
• Glossectomies
• Surgical procedures →improve patency of airway.
• Occlusal adjustments.
• Corticotomy assisted molar intrusion.
Causes of relapse
1. Unfavorable growth patterns
2. Unfavorable tongue posture or size, orofacial muscula-
ture & respiratory problems.
3. Resumption of a digit-sucking habit.
4. Inappropriate orthodontic tooth movement
5. Wrong orthognathic Surgery planning
Retention
• Prolonged retention with fixed/removable retainers
→in active growth.
• Intrusion or prevention of eruption of posterior
maxillary teeth →until growth ceases.
• Prevent labial flaring of incisors

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190
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19
1. Basic terminologies
2. Prevalence
3. Aetiology deep overbite
4. Principles of deep incisor overbite reduction
5. Method of treating DOB
6. Management of overbite
In this Chapter
Deep bite

DEEP BITE
200
Overbite (OB) describes the vertical overlap of the upper
and lower incisors measured perpendicular to the occlusal
plane with the posterior teeth in the occlusion (BSI 1983).
OB is measured perpendicular to the occlusal plane in mm or
expressed as a ratio. The normal range for the maxillary inci-
sors to vertically overlap the mandibular incisors is 2–4 mm,
or one-third to one-half of mandibular incisors crown height.
Basic terminologies
These include:
• Deep bite: When the maxillary incisors overlap, the
mandibular incisor crowns vertically by greater than
one-half of the lower incisor crown height.
• Complete: There is contact between incisors or the
incisors and opposing mucosa.
• Incomplete: if there is no contact between incisors
or the incisors and opposing mucosa.
• Traumatic overbite: When the increased overbite is
causing trauma to the upper or lower mucosa. Up-
per incisors mainly cause trauma to the lower labial
mucosa, especially in the case of class II div 2. In
contrast, the lower incisors can cause upper palatal
mucosa in the case of class I div and div II.
Prevalence
Worldwide, the prevalence is 11.13 % in mixed dentition and
14.98% in the permanent dentition (Alhammadi, 2018).
Aetiology deep overbite
These include:
• Skeletal and growth factors: A reduced lower face
height in conjunction with a Class II jaw relation-
ship results in the absence of an occlusal stop to the
lower incisors, which subsequently over-erupt lead-
ing to an increased overbite (Pancherz et al., 1997).
Forward growth rotation, i.e. counter-clockwise
(average -7°), can cause skeletal deep bite leading
to decreased anterior lower face height or increased
posterior face height (Nielsen, 1991).
• Soft Tissues such as high lower lip line (Nicole 1954,
Ridley 1960), hyperactive or “strap-like” lower lip
(Lapatki et al., 2002), and hyperactive Mentalis mus-
cle (Karlsen, 1994). These soft tissue factors result in
deep bite by retroclination of the lower incisor.
• Dental factors such as overeruption of the incisors,
long central and short lateral incisors, which results
in the lateral incisors ‘escaping’ from the effects of
the lower lip force, increased crown root angle of the
upper incisor, known as the Collum angle (McIntyre
and Millett, 2003), and thin incisors with small cin-
gulum.
Principles of deep incisor overbite reduction
These include:
• True incisor intrusion is mainly indicated in an
adult patient with excessive maxillary incisors show-
ing at rest and a patient with long lower facial height
with over erupted incisors.
• Levelling of the arch through molar and premolar
eruption and extrusion (Cobourne and DiBiase,
2015). Keeping in mind that the condyle will com-
pensate for the extrusion in a growing patient and
maintain the anterioposterior relationship, but in
the adult, the condyle does not compensate for that
(McDowell & Baker, 1991). however, the slight hing-
ing open of the mandible in adults, associated with
molar extrusion, seems to be stable due to the ten-
dency to small continued vertical growth found in
adults (Behrents 1986).
• Incisor proclination or relative incisor intrusion
(Ireland et al., 2016). Eberhart et al. (1990) stated
that 5 degrees of incisor proclination reduced the
overbite by 1 mm on average.
• Distal tipping of posterior teeth
• Surgery to change the anteroposterior and vertical
relationship.
Consideration factors for the method of treating DOB
These include:
• Age and the remaining growth affect the degree of
incisor show. It is preferable to accept slightly in-
creased incisor show in the growing patient since
soft tissue maturation would mask some of the un-
derlying problems with ageing
• Patient compliance and concerns
• Vertical height relationship: For instance, it is rec-
ommended to avoid posterior teeth extrusion in
high angle cases.
• Faial profile: It is recommended to avoid relative in-
trusion (proclination of incisors) in full or convex
profile.
• If the main aim of the treatment is to reduce the
amount of incisor show, then absolute intrusion is
indicated. Generally, the incisors show they depend
on the following factors: Lip length, crown height,
lip activity, gingival height and level and the degree
of anterior maxillary height.
• Incisor inclination at the start of the treatment: If
the incisor is retroclined, deep bite management via

DEEP BITE 201
relative intrusion is preferable.
• In the thin gingival biotype (labial surface of inci-
sors), management of the deep bite via relative intru-
sion should be avoided.
• Intra-arch relationship such as the overjet and the
arch length discrepancy. If the arch is crowded or the
overjet is reduced, reducing the overbite by proclina-
tion of incisors is preferable.
Management of overbite
These include:
1. Upper removable appliance (URA): URA with anterior
bite plane in a growing patient can be used to correct deep
bite (Millett et al., 2006). Providing that the rate of molar
eruption does not exceed the relative rate of vertical condy-
lar growth, there should be no backward mandibular rotation
(McDowell & Baker, 1991). Bacceti et al. 2012 found that us-
ing URA at early permanent dentition results in a significant
and faster reduction in overbite than in the mixed dentition.
Simons and Joondeph in 1973 found that treatment during
early permanent dentition is even more stable.
2. Extraoral traction: Cervical pull headgear is a commonly
used extraoral appliance to reduce deep overbite. J hooks are
associated with a high risk of cause root resorption (Linge
and Linge 1983). Degushi 2008 compared TAD with J hook
for intrusion and found the result is 3.1 and 1.3mm, respec-
tively. Alternatively,
3. Dahl appliance: The Dahl concept involves an anterior
bite-opening appliance in adults to increase the inter-occlu-
sal distance and allow the intrusion of teeth in contact with
the appliance (usually anterior teeth) and extrusion of those
unopposed (posterior teeth). It is beneficial in cases of tooth
surface loss, where an increase in the occlusal vertical dimen-
sion is required to produce enough space for a definitive res-
toration (Cobourne and DiBiase, 2015, Björk, 1969).
4. Appliance selection: Begg and Tip edge appliances are ef-
ficient in deep bite reduction. With lingual appliances, verti-
cal control is clinically more efficient than conventional labial
appliances because of the ribbon-wise slot configuration and
the proximity of the force applied to the centre of rotation
and root, in addition to the anterior bite effect of the lingual
appliance.
5. Fixed appliance settings such as:
• Hybrid bracket positioning and variation (Hold-
away, 1952).
• Partial ligation of the distally inclined canines to
avoid overbite deepening.
• Avoid using laceback or cinch back to allow the arch
to lengthen.
• Bonding the second permanent molar leads to addi-
tional vertical posterior anchorage and second mo-
lar extrusion.
6. Continuous rigid archwires: Levelling of the curve of
Spee can be accomplished with continuous archwires by plac-
ing an exaggerated curve of Spee in the upper archwire and
a reverse curve of Spee in the lower archwire. Although it
is recommended to use a rectangular archwire for this pur-
pose, Al-Qabandi et al., in 1999, carried out a prospective
randomised clinical study to compare the effects of rectan-
gular and round archwires in levelling the curve Spee and
they found no significant difference in incisor proclination
between these two groups.
7. Counterforce or rocking chair NiTi archwires (Modi-
fied Tweed mechanics): Rocking chair wire acts by the intru-
sion of anterior teeth, extrusion of posterior teeth and pro-
clination of anterior teeth. A study by Clifford et al. (1999)
showed that with rocking chair wires, the second molars in-
trude rather than extrude. It is essential to consider the side
effects of rocking chair wire such as distobuccal molar rota-
tion, buccal rolling, premolar expansion, incisor proclination
and possible asymmetric bite opening. Hypothetically, 15 de-
grees of (unwanted) labial crown torque would result from
leaving a curve of Spee of 5 mm at its greatest depth to go
completely passive.
Methods to reduce the unwanted labial tipping of lower in-
cisors during levelling
These include:
• A lower incisor prescription with lingual crown
torque.
• A lingual crown torque is built in the rectangular
wire.
• An intra-arch space to allow traction and counteract
proclination.
• Class 3 elastic may cause unwanted anchorage loss
in the upper arch.
8. Auxiliary appliances such as:
• Fixed anterior bite turbo.
• Class 2 bite corrector.
• Class II inter-maxillary elastics
9. Auxiliary archwires such as:
• The “HG-tandem”: The “HG-tandem” mechanics
in the maxillary arch consisted of a 2 x 4 lever arch,
cinched back, and gabled 1 mm anterior to the mo-
lar band. It achieved around 1.9 mm of true incisor
intrusion (Hans 1994)
• Anchor bend approach: It is used during the first

DEEP BITE
202
stage of the Begg technique and is most useful for a
patient with some growth. Mulligan (1980) advocat-
ed a similar approach using the edgewise appliance.
• Auxiliary levelling arch: it is made from 17 × 25 mil
TMA wire, inserted into the auxiliary tube on the
molar and tied anteriorly beneath the 0.018 SS base
arch.
• Connecticut intrusion: in this technique, the brack-
ets of the 4 maxillary incisors are laced-back. A pas-
sive 0.016-in round segmental archwire is placed on
maintaining the initial position of the 4 maxillary
incisors. A 0.016x0.022-in long NiTi intrusion arch
is tied below the lateral incisor brackets and cinched
back to prevent facial tipping of the incisors (Nanda
1998).
10. Segmental archwire techniques such as:
A. Burstone archwires mechanics: In this technique, the buc-
cal segments are first aligned and then stabilised using a full
dimension rectangular archwire, the same for the anterior
segment. In addition to this, a heavy lingual arch is used to
connect the right and left posterior segments. An auxiliary
depressing arch is then placed in the auxiliary tube on the
first molar and is used to apply force against the anterior seg-
ment. It is recommended that no more than the four inci-
sors be incorporated in the intrusive segment. If the canines
were also included, the anchorage balance would shift unac-
ceptably towards distal tipping of the buccal segment teeth.
Burstone recommends that the dimension of the wire be
.018x.025ss wire with a two and a half turn helix, alternative-
ly, .019x.025 TMA without a helix can be used. When passive,
the wire should lie just gingival to the incisor teeth and apply
a light force of 10-15g when activated. The Burstone intrusion
arch is tied beneath the brackets, not into the bracket slots
occupied by the anterior segment wire. It still has the effect of
wanting to tip the incisors forward as they intrude, but two
strategies may be employed to prevent this: (a) the archwire
may be tied back against the posterior segment. However, this
can strain the posterior anchorage, (b) the point of force ap-
plication may be altered by tying it more distally. It is feasible
to intrude asymmetrically, which requires only adjusting the
teeth placed in stabilising and intrusion segments and tying
the auxiliary intrusion arch in the area where the intrusion is
necessary. If an intrusion is desired only on one side, either
a cantilevered auxiliary wire extending from one molar or a
molar-to-molar auxiliary arch can be used. The key is tying
the auxiliary arch at the point where the intrusion is desired.
B. Rickett’s utility arch: The utility arch is characterised by
step-down bends between the first molar and the lateral in-
cisors, and it is constructed in .016” square Elgiloy. In most
cases, the archwire is placed into the brackets with slight la-
bial root torque to control the inclination of the teeth as the
incisors move labially while they intrude. Success in using
these bypass arches depends on the forces being light. Two
weaknesses of the bypass arch systems limit the amount of
true intrusion that can be obtained (a) extrusion of the first
molar can occur through distal tipping of molars. Hence,
high-pull headgear may be used, especially in non-growing
patients, (b) the intrusive force against the incisors is applied
anterior to the centre of resistance which pushes the incisors
to tip forwards as they intrude.
Advantages of segmental archwires technique
These include:
• A long-range of action, because of the long inter-
bracket span
• More easily estimated biomechanical effects
• Frictionless
Disadvantages of segmental mechanics
These include:
• Complexity of fabrication
• Poorer control of overall arch form
• Less ‘fail-safe’ effect if the case is unsupervised for a
period
• Oral hygiene difficulties and patient discomfort if
the wires impinge on the mucosa.
• Proclination and wagon wheel effect
11. Absolute anchorage: This can be delivered using os-
seointegrated implants, onplants or miniscrews (TADs).
Degushi in 2008 compared TAD with J hook for intrusion
and found the result is 3.1 and 1.3mm, respectively. A study
by Aras and Tuncer 2016 compared using TADs directly to
intrude the posterior teeth or placing the TADs posteriorly
to support an intrusion archwire. They found that intrusion
anchoring from posterior mini-implants is preferred in cases
of upright incisors.
12. Surgical treatment of the Deep Overbite: In case of
an increased lower facial height, moderate curve of spee is
corrected by true intrusion of incisors, however, surgery may
involve lower anterior dentoalveolar stepdown and BSSO ad-
vancement. In case of a reduced lower facial height, surgery
may involve 3 point landing BSSO advancement.
Effectiveness of different approaches
Investigations comparing reverse curves of Spee archwire
(modified Tweed technique) to Burstone mechanics for over-
bite reduction: Weiland 1996, found no significant difference
between Burstone mechanics and modified Tweed mechan-
ics as a result of the overbite correction. However, Burstone
mechanics results in more incisor intrusion while Tweed
mechanics produces minimal intrusion and a high amount
of molar extrusion. Ng 2005 systematic review showed that

DEEP BITE 203
the segmented arch technique in no growing patients has 1.5
mm of maxillary incisor intrusion and 1.9 mm of mandibular
incisor intrusion.
Investigations comparing reverse curves of Spee AW (modi-
fied Tweed technique) to sectional arches for overbite reduc-
tion (Rickett utility arch): Dake & Sinclair in 1989 showed
that Ricketts and Tweed-type arch levelling techniques were
successful in overbite correction with minimal increases in
mandibular plane angle and anterior facial height noted. They
also found mandibular incisors procline more in the Ricketts
group with a greater post-treatment uprighting and overbite
relapse than in the Tweed group.
Exam night review
Deep bite represents a condition when the maxillary incisors
overlap the mandibular incisor crowns vertically by greater
than one-half of the lower incisor crown height. Worldwide,
the prevalence is 11.13 % in mixed dentition and 14.98% in
the permanent dentition (Alhammadi, 2018).
Aetiology deep overbite
• Skeletal and growth factors (Pancherz et al., 1997)
• Soft tissues factors (Nicole 1954, Ridley 1960)
• Dental factors (McIntyre and Millett, 2003)
Principles of deep incisor overbite reduction
• True incisor intrusion
• Levelling of the arch (Cobourne and DiBiase, 2015).
• Incisor proclination or relative incisor intrusion
• Distal tipping of posterior teeth
• Surgery to change the anteroposterior and vertical
relationship.
Management of overbite
• Upper removable appliance (URA) (Millett et al.,
2006).
• Extraoral traction (Linge and Linge 1983).
• Dahl appliance (Cobourne and DiBiase, 2015,
Björk, 1969).
• Appliance selection
• Fixed appliance settings
• Continuous rigid archwires
• Counterforce or rocking chair NiTi archwires
(Modified Tweed mechanics)
• Auxiliary appliances
• Auxiliary archwires
• Segmental archwire technique
• Absolute anchorage
• Surgical treatment of the Deep Overbite
References
HOLDAWAY, R. A. 1952. Bracket angulation as applied to the
edgewise appliance. The Angle Orthodontist, 22, 227-236.
HOUSTON, W. J. B. 1989. Incisor edge-centroid relationships and
overbite depth. European Journal of Orthodontics, 11, 139-143.
bil, 1, 131-47.
KIM, Y. H. 1974. Overbite depth indicator with particular refer-
ence to anterior open-bite. American Journal of Orthodontics and
SON, P., WILLIAMS, A. & DE OLIVEIRA, C. M. 2006. Orthodon-
tic treatment for deep bite and retroclined upper front teeth in
children. Cochrane Database Syst Rev, Cd005972.
NAHOUM, H. I. 1977. Vertical proportions: a guide for prognosis
and treatment in anterior open-bite. Am J Orthod, 72, 128-46.
NAINI, F. B., GILL, D. S., SHARMA, A. & TREDWIN, C. 2006.
The aetiology, diagnosis and management of deep overbite. Dent
Update, 33, 326-8, 330-2, 334-6.
NIELSEN, I. L. 1991. Vertical malocclusions: etiology, develop-
ment, diagnosis and some aspects of treatment. Angle Orthod, 61,
247-60.
SKIELLER, V., BJORK, A. & LINDE-HANSEN, T. 1984. Predic-
tion of mandibular growth rotation evaluated from a longitudinal
implant sample. Am J Orthod, 86, 359-70.

20
1. Aetiology and profile
2. Features of low angle cases
3. Predictors of low angle
4. Principals of treatment
5. Methods to reduce overbite
6. The Dahl concept
In this Chapter
Low Angle Cases

Low Angle 207
The decreased vertical proportion (short face) charac-
terised by deep bite is called low angle. In a cephalometric
analysis of a low angle patient, the majority of ceph values are
lower from standard deviation:
• Maxillary mandibular plane angle (MMPA) lesser
than 21.
• Frankfort mandibular plane angle (FMPA)lesser
than 22.
• SN-mandibular plane lesser than 28˚.
• SN-palatal plane lesser than 5˚.
• MMA angle is greater than 29˚.
• Y-axis angle lesser than 62˚.
• Jarabak ratio is greater than 64%.
• Sum of inner angles less than 392˚.
• Individuals of the short face type are characterised
by short anterior lower face height (also known as
hypodivergent).
Aetiology of low angle cases
The main aetiology is the forward growth rotation (average
is -7°) (Bjork and Skieller, 1972). The forward growth rota-
tion has been thought due to an increase in the normal inter-
nal rotation and a decrease in the external rotation (Nanda,
1990).
Features of low angle cases
These include:
1. Skeletal features such as a short square-shaped face, low
vertical proportions, Class II skeletal relationship
• Hypertrophic mentalis and masseters (type II col-
lagen fibers) (Hunt et al., 2006).
• Skin folds can be seen lateral to oral commissure.
• Acute labiomental and nasolabial angles.
• Prominent chin
• Increased incisor show on rest and smile.
• The overbite can be increased and complete with
or without palatal trauma (Ingervall and Thilander,
1974).
• Lower incisors are typically proclined and crowded.
• The upper arch is broad, and the palatal vault is flat
often.
• Large interocclusal space.
Predictors of low angle
These include Bjork’s 7 structural signs that identify low angle
cases (Björk, 1969):
• Decreased lower AFH.
• Increased interincisal angle.
• Forward inclination of the condylar head.
• The curvature of the mandibular canal is greater
than the mandibular contour.
• The lower mandibular border is rounded anteriorly,
concave at the angle, and has an absent antegonial
notch.
Principals of treatment
These include:
• True incisor intrusion.
• Posterior extrusion in a growing patient (Cobourne
and DiBiase, 2015)
• Incisor proclination or relative incisor intrusion.
• Backward rotation of the mandible.
In adults no compensatory growth; therefore, posterior ex-
trusion treatment is considered unstable. Adult orthodontic
treatment is consequently restricted to incisor intrusion or
proclination.
Methods to reduce overbite
Removable appliances such as:
• Upper removable appliance with anterior bite plane.
• Low pull headgear.
• Dahl appliance.
• Functional appliances.
Fixed Appliances such as:
• Upper fixed bite plane (bite turbo).
• Lingual brackets. Lingual brackets act as a bite plane.
• Begg or Tip-Edge appliances.
• Lower archwire with the reverse curve of Spee.
• Upper archwire with an increased curve of Spee.
• Intrusion arches, i.e. Rickets & Burstones utility
arch.
• Intermaxillary elastics.

Low Angle
208
• Incorporation of 2nd molars may extrude first mo-
lars and second premolars (Eberhart et al., 1990).
• Anchor bends to flare labial segment and distal tip
posterior teeth.
• TADs to intrude incisors and extrude the molars
(Clifford et al., 1999).
• Combined orthodontic-surgical approach.
The Dahl concept
The Dahl concept involves an anterior bite-opening appliance
in adults to increase the inter-occlusal distance and allow the
intrusion of teeth in contact with the appliance (usually an-
terior teeth) and extrusion of those unopposed (posterior
teeth). It is beneficial in cases of tooth surface loss, where an
increase in the occlusal vertical dimension is required to pro-
duce enough space for a definitive restoration (Cobourne and
DiBiase, 2015, Björk, 1969).
Exam night review
Features of low angle cases
• Short square-shaped face.
• Hypertrophic masseters (type II collagen fibers)
(Hunt et al., 2006).
• Skin folds can be seen lateral to oral commissure.
• Reduced incisor show on a smile.
• Deep overbite (Ingervall and Thilander, 1974).
• Lower incisors are typically proclined and crowded.
• The upper arch is broad, and the palatal vault is flat
often.
• Increased interocclusal space.
Bjork’s 7 structural signs of low angle (Björk, 1969)
• Increased interincisal angle.
• Decreased lower AFH.
• Forward inclination of mental symphysis with a
prominent chin.
• Forward inclination of the condylar head.
• Curvature of the mandibular canal is greater than
the mandibular contour.
• Absence of antegonial notch.
Treatment options
• Posterior extrusion.
• Incisor intrusion.
• Incisor proclination.
• Backward rotation of the mandible.
Method to reduce overbite
• Upper removable appliance with anterior bite plane/
turbos.
• Upper fixed bite plane (bite turbo).
• Low pull headgear.
• Dahl appliance.
• Functional appliances.
• Lingual brackets.
• Begg or Tip-Edge appliances.
• Lower archwire with the reverse curve of Spee.
• Upper archwire with an increased curve of Spee.
• Segmental archwires or intrusion arches, i.e. Rickets
& Burstones utility arch.
• Intermaxillary elastics.
• Banding/bonding of 2nd molars can also be done to
extrude first molars and second premolars (Eberhart
et al., 1990).
• Anchor bends.
• TADs (Clifford et al., 1999).
• Combined orthodontic-surgical approach.

Low Angle 209
References
BJO¨RK, A. & SKIELLER, V. 1972. Facial development and tooth
eruption: An implant study at the age of puberty. American Journal
BJÖRK, A. 1969. Prediction of mandibular growth rotation. Ameri-
can Journal of Orthodontics, 55, 585-599.
CLIFFORD, P. M., ORR, J. F. & BURDEN, D. J. 1999. The effects of
increasing the reverse curve of Spee in a lower archwire examined
using a dynamic photo-elastic gelatine model. Eur J Orthod, 21,
213-22.
EBERHART, B. B., KUFTINEC, M. M. & BAKER, I. M. 1990. The
relationship between bite depth and incisor angular change. Angle
Orthod, 60, 55-8.
HUNT, N., SHAH, R., SINANAN, A. & LEWIS, M. 2006. North-
croft Memorial Lecture 2005: muscling in on malocclusions: cur-
rent concepts on the role of muscles in the aetiology and treatment
of malocclusion. J Orthod, 33, 187-97.
bil, 1, 131-47.
IRELAND, A. J., SONGRA, G., CLOVER, M., ATACK, N. E.,
SHERRIFF, M. & SANDY, J. R. 2016. Effect of gender and Frankfort
mandibular plane angle on orthodontic space closure: a random-
ized controlled trial. Orthod Craniofac Res, 19, 74-82.
NANDA, S. K. 1990. Growth patterns in subjects with long and
short faces. Am J Orthod Dentofacial Orthop, 98, 247-58.
PROFFIT, W., FIELDS, H. & SARVER, D. 2006. Contemporary
Orthodontics 4th Edition. Mosby, USA, 411.

HYPODONTIA
210
21
1. Classification of hypodontia
2. Candidate genes in hypodontia
3. Incidence of hypodontia
4. Aetiology and theories of hypodontia
5. Clinical presentation of hypodontia
6. Malocclusion features of hypodontia patients
7. Indications for treatment
8. General treatment principles
9. Options for treatment
10. Auto-transplantation
11. Space closure
12. Problems and solutions of cuspid substitution
13. Benefits of cuspid substitution
14. Points to consider during space closure
15. Reopen or redistribute space
16. Space opening and prosthetic replacement
17. Interim prosthesis of a space of a missing tooth
18. Types of final restorations
19. Criteria for implant placement
20. Success of dental implants
21. Treatment options for absent premolars
22. Evidence summary
In this Chapter
Hypodontia
Written by: Mohammed Almuzian, Haris Khan, Maham Batool,Taimoor Khan, Rim Fathalla, Lubna
Almuzian, Dalia El-Bokle

HYPODONTIA 211
Hypodontia is the developmental absence of one or more
teeth, excluding third molars (Goodman et al., 1994), also
known as selective tooth agenesis.
Classification of hypodontia
These include:
1. According to the severity of missing teeth (Hobkirk et al.,
1995)
• Mild: 1 to 2 missing teeth, also called Hypodontia.
• Moderate: 3 to 6 missing teeth.
• Severe: more than 6 missing teeth.
Mild forms of hypodontia are more common (81.6%) than
moderate (14.3%) and severe (3.1%) (Khalaf et al., 2014).
2. According to the number of missing teeth (Hobkirk et
al., 1994)
• Hypodontia: Agenesis of 1-6 teeth excluding third
molars.
• Oligodontia: Agenesis of more than six teeth, ex-
cluding the third molars.
• Anodontia: complete absence of teeth.
3. According to inheritance pattern
A. Non-syndromic: It can be sub-classified according to the
method of occurrence (Burzynski and Escobar, 1983).
• Sporadic hypodontia: This involves 33% of hy-
podontia cases.
• Familial or inherited: This form follows autosomal
dominant, autosomal recessive or autosomal sex-
linked patterns of inheritance, with considerable
variation in both penetrance and expressivity.
Non-syndromic hypodontia can also be sub-classified ac-
cording to the teeth involved and their numbers:
• Localized incisor–premolar hypodontia (OMIM
106600), which affects only one or some of these
teeth. This is the most common form and seen in
around 8% of Caucasians (Nieminen et al., 1995).
• Oligodontia (OMIM 604625) occurs in around
0.25% of Caucasians and can involve all classes of
teeth (Sarnas and Rune, 1983).
B. Syndromic: Hypodontia can be associated with an un-
derlying genetic disorder. Hypodontia has been reported in
more than 50 syndromes, some of them are given in Table 1.
Table 1: Syndromes associates with hypodontia
Syndrome Associated gene(s)
Anhidrotic ectodermal
dysplasia(Visinoni et al.,
2009)
EDA
Ehlers–Danlos syndrome ADAMTS2
Incontinentia pigmenti NEMO
Limb mammary TP63
Reiger syndrome PITX2
Witkop (Jumlongras et al.,
2001)
MSX1
Ellis–van Creveld syndrome EVC or EVC2
Cleft lip and palate and Van de Wound syndrome
Candidate genes
These include:
Generally, MSX1 represents a candidate gene for both syn-
dromic and non-syndromic hypodontia.
1. Candidate genes for non-syndromic hypodontia (Vas-
tardis et al., 1996, Lammi et al., 2004, Cobourne, 2007b)
are:
• MSX1 and MSX2: they are expressed in regions of
condensing mesenchyme of tooth germ and associ-
ated with premolars and lateral incisors and some-
time associated with severe hypodontia.
• EDA gene mutations usually includes the loss of
mandibular and/or maxillary incisors and canines.
• PAX9 is a transcription factor during tooth mor-
phogenesis and is associated with molar hypodontia.
• AXIN2 is involved in cell growth proliferation and
differentiation and it is mainly associated with Finn-
ish family hypodontia.
Incidence of hypodontia
In summary:
1. Type of dentition: In Caucasians, localized incisor–pre-
molar hypodontia has been reported to be 8%, whilst oligo-
dontia occurs in around 0.25% (Nieminen et al., 1995, Sarnas
and Rune, 1983). Prevalence of hypodontia is high in Africa
(13.4%), followed by Europe (7%). Asians and Australians
have a similar prevalence of 6.3%. The lowest prevalence of
4% was reported in Latin America and the Caribbean (Khalaf
et al., 2014). However, another systematic review and meta-
analysis found no difference in prevalence among popula-
tions of various ethnicities and geographic locations (Rakh-
shan and Rakhshan, 2016).
2. Ethnicity variation: In Caucasians, localized incisor–pre-
molar hypodontia has been reported to be 8%, whist oligo-

HYPODONTIA
212
dontia occurs in around 0.25% (Nieminen et al., 1995, Sarnas
and Rune, 1983). Prevalence of hypodontia is high in Africa
13.4% followed by Europe 7%. Asian and Australians have
a similar prevalence at 6.3%. The lowest prevalence of 4%
was reported in Latin America and Caribbean (Khalaf et al.,
2014). However, another systematic review and meta-anal-
ysis found no difference in prevalence among population of
various ethnicities and geographic location (Rakhshan and
Rakhshan, 2016). In the UK population, the incidence of hy-
podontia is 5.3-5.6% (Polder et al., 2004).
3. Gender variation: Hypodontia is more frequently report-
ed in females (Fekonja, 2005b, Khalaf et al., 2014). Females
to male ratio has been reported as F:M = 3:2 (Larmour et al.,
2005, Rolling, 1980). The incidence in males is 4.6%, and in
females 6.4% (Polder et al., 2004).
4. Jaw and side of occurrence: Increased incidence of miss-
ing teeth has also been reported in the maxilla (Sisman et al.,
2007) and in the mandible (Kirzioglu et al., 2005, Rolling,
1980). No difference in right or left side predilection has been
found (Sisman et al., 2007), but some studies reported an in-
creased incidence on the left side (Wisth et al., 1974, Roll-
ing, 1980), while others found a right sided predominance
(Fekonja, 2005b).
5. Unilateral vs bilateral hypodontia: Overall, unilateral
missing teeth are more common, however, upper lateral in-
cisors are more commonly missing bilaterally (Chung et
al.,2008, Polder et al.,2004). Unilateral missing teeth are more
common in the case of the upper and lower second premolars
(Polder et al.,2004)
6. Sequence of hypodontia: Teeth that are present at the end
of each series are more susceptible to agenesis. It has been
hypothesized that terminal teeth form at last in each tooth
series; thus, they can fall below the threshold that is required
for normal dental development (Thesleff, 1996). Mesial teeth
are more developmentally stable than teeth at the distal end
of a series (Hobkirk et al., 2010). Some believe that these teeth
develop from two embryological origins, hence, they are at
high risk of being missing (Al-Ani et al., 2017a). In summary:
• Third molars are the most commonly absent teeth
with an incidence of 25-35% (Peck et al., 1996).
• Premolars can form as late as 9 years of age. Lower
5s are the most commonly absent (2.6%), followed
by upper 5s then 4s (Wisth et al., 1974). Peck has re-
ported a 3% incidence of missing second premolars
• Canines, first and second molars are rarely missing
(Symons et al., 1993)
• Absent maxillary lateral incisors occur in 2% of the
population (Peck et al., 1996). Familial tendency has
been found for both diminutive and missing later-
als (Zilberman et al., 1990). Diminutive laterals are
often present in cases of palatally impacted canines
(Brin et al., 1986). A meta-analysis found that pa-
tients with unilateral diminutive shaped incisors
have a high chance of agenesis (55%) of the lateral
incisor on the opposing side (Hua et al., 2013).
• Lower incisors more commonly absent in the Asian
population, whilst the incidence among Caucasians
is 0.2% (J Neal and E Bowden, 1988).
In Caucasians, the most commonly missing teeth after third
molars are lower second premolars > upper lateral incisors >
upper second premolars > lower central incisors (Larmour et
al., 2005). In some Asian populations, lower central incisors
are reported to be commonly missing.
Aetiology and theories of hypodontia
A series of molecular regulatory factors and pathways are in-
volved in tooth development. Factors such as FGF, BMP and
Wnt signaling pathway take part in epithelial-mesenchymal
interactions that are required for normal development of
teeth. Any disturbance in these pathways may lead to tooth
agenesis (Zhu et al., 1996). Several theories have been pro-
posed including:
1. Evolutional theory: Evolution of humans has resulted in a
decrease in size of jaws and number of teeth present in these
jaws (Vastardis, 2000). Generally, mesial teeth are more de-
velopmentally stable than teeth at distal end of series (Hob-
kirk et al., 2010)
2. Anatomical theory: Dental lamina of teeth that are pres-
ent at fusion regions of jaw bones or embryological processes
(Al-Ani et al., 2017a), are more susceptible to environmental
defects (Svinhufvud et al., 1988). Another theory is that the
areas which developed at a later stage are more susceptible to
tooth developmental disturbances (Kjær et al., 1994).
3. Environmental theory includes (Al-Ani et al., 2017b):
i. Systemic disruption of dental lamina by:
• Chemotherapy and radiotherapy in infancy (Parkin
et al., 2009, Näsman et al., 1997).
• Infection e.g. rubella infection (Cameron and Samp-
son, 1996).
• Drug interaction e.g. thalidomide (Gilbert-Barness,
2010).
• Toxin (Brook, 2009)
ii. Localised disruption of dental lamina by:
• Trauma, such as fracture of alveolar process (Brook,
2009)
• Cleft of alveolus resulting in transection of dental
lamina

HYPODONTIA 213
• Nutritional deprivation e.g. insufficient calcium in
diet.
4. Genetic factors: Polygenic multifactorial model of aetiol-
ogy has been proposed as an aetiology for hypodontia, with
many studies reporting a strong influence of genetic factors
on hypodontia. Twin studies demonstrated the autosomal
dominant inheritance with incomplete penetrance and vari-
able level of expressivity (Cobourne, 2007a). Non-syndromic
hypodontia has a variable mode of inheritance, and can be
autosomal dominant, autosomal recessive or autosomal sex
linked (Cobourne et al., 2012). Almost 300 genes are involved
in the development of the dentition. Some of the genes most
frequently associated with non-syndromic hypodontia are
presented in table 1.
Clinical presentation of hypodontia
Clinically, patients with hypodontia may present with (Gill
and Barker, 2015):
• Retained primary teeth,
• Infra-occluded primary teeth,
• Ankylosed primary teeth,
• Absent primary tooth,
• Delayed / asymmetric eruption of permanent teeth,
• Conical / reduced crown morphology of permanent
teeth present, and
• Lack of alveolar bone growth in three planes of
space.
Malocclusion features of hypodontia patients
The dental, occlusal, alveolar and skeletal features of patients
with hypodontia include:
A. Skeletal features (depending on the severity of maloc-
clusion) such as:
• Retrognathic and hypoplastic maxilla (Wisth et al.,
1974, Hobkirk et al., 1995).
• Reduced MMPA and reduced vertical dimensions.
(Taju et al., 2018).
• Low mandibular plane angle associated with re-
duced lower anterior facial height and protrusive
lips (Chung et al., 2000).
B. Alveolar features (Cobourne and DiBiase, 2015) such
as:
• Lack of alveolar bone
• Fairly flat palatal vault which results in reduced
anchorage capacity of upper removable appliances,
Nance palatal arch or implant placement.
C. Occlusal features (Fekonja, 2005b) such as:
• Upright incisors
• Generalized spacing and rotation of teeth adjacent
to the missing teeth.
• Over-erupted incisors
• Increased overbite
D. Dental features such as:
• Enamel hypoplasia
• Microdontia (Graber, 1978) or conical / reduced
crown morphology of permanent teeth present
(Brook, 1984)
• Molar taurodontism
• Short rooted teeth.
• Absent primary tooth
• Prolonged retention of primary teeth (Kurol and
Thilander, 1984).
• Ankylosed primary teeth,
• Infra-occlusion of primary teeth (Kurol and Thilan-
der, 1984).
• Ectopic eruption or impaction of the adjacent teeth,
particularly maxillary canines. Up to 5% of those
with absent lateral incisors may present with maxil-
lary canine impaction. (Brin et al., 1986)
• Transposition (Peck et al., 1996)
• Delayed and asymmetric eruption of permanent
teeth. The second premolars are particularly prone
to a delay in dental development, and may not be
visible radiographically until the age of 9 years.
Hence, a diagnosis of their absence should be made
with caution before this age. (Wisth et al., 1974)
• Lack of alveolar bone growth in three planes of
space.
Indications for treatment
Several indications were proposed for treating hypodontia
including (Shaw et al., 1980):
• Functional needs: Hypodontia has an adverse im-
pact on quality of life measures (Akram et al., 2011,
Akram et al., 2013, Wong et al., 2006)
• Aesthetic needs
• Dental health problems including food impaction
due to tipped or drifted teeth, traumatic over bite
and infraoccluded primary teeth
General treatment principles
Inter-disciplinary treatment involving orthodontist, prosth-

HYPODONTIA
214
odontist, oral surgeon and restorative dentist is necessary
(Stevenson et al., 2013, Hobkirk et al., 2010), taking into con-
sideration several factors such as:
A. Complications /difficulties with treatment: The follow-
ing complications are encountered while treating cases with
hypodontia (Grahnén, 1956b):
• Aesthetic impact of treatment
• Increased overall cost of treatment
• Increased treatment time
• Anchorage difficulties
• Poor root parallelism for implants
• Risk of relapse e.g. spaces reopening
• Atrophy and loss of bone
• Compromised treatment outcome: Common issues
faced in treating these patients include space man-
agement, uprighting and aligning teeth, manage-
ment of the deep overbite, and retention (Carter et
al., 2003).
B. Treatment factors: The following factors should be con-
sidered (Hobkirk et al., 1995):
• Age
• Medical history
• Patient’s opinion and co-operation
• Facial profile
• Smile line
• Gingival line
• Malocclusion and extent of hypodontia
• Intra- and inter-arch relationships
• Dental features size, shape, colour of the adjacent
teeth
• Clinical situation of retained teeth.
C. Sequence of treatment
Both orthodontists and restorative dentists should estab-
lish realistic objectives rather than idealistic, which include
(Spear et al., 1997):
1. Create a diagnostic set-up (set up of current dentition) or
Kesling set up (repositioning of dentition).
2. Determine the sequence of orthodontic treatment.
3. Building-up malformed teeth and answering the follow-
ing questions:
• Where should the maxillary lateral incisor (U2) be
positioned mesiodistally relative to the central inci-
sor (U1) and canine (U3). Commonly, restorative
dentists prefer to have more space between U2 and
U3.
• Where should U2 be positioned bucco-lingually: to-
ward the labial, in the centre of the ridge, or toward
the lingual? Depend on the type and thickness of fi-
nal restoration.
• Where should U2 be positioned inciso-gingivally?
This relationship is determined by the position of
the gingival margins.
4. Evaluate gingival aesthetics.
5. Determine space required by golden proportion, universal
mesio-distal width, contra lateral-tooth size or Bolton analy-
sis (Bolton, 1958).
6. Provision of space to facilitate restorative treatment.
7. Take progress radiographs, and measure the space with
the implant T ruler.
8. Occlusal adjustment.
9. Interact with restorative dentists during finishing.
Options for treatment
These include (Gill and Barker, 2015):
A. No active treatment: No treatment is necessary if there is
no malocclusion associated and the patient is satisfied with
his/her dentition, or unwilling to commit to lengthy and
costly treatment (Kokich and Kinzer, 2005).
B. Interceptive treatment: General dentists play an important
role in early detection of developmentally missing incisors.
Early extraction of primary canine to prevent / intercept
the associated impaction of the maxillary canine has been
advocated in many studies (Parkin et al., 2017). Intercep-
tive extractions of primary teeth are advised in the mixed
dentition stage for maximum space to be closed spontane-
ously (Lindqvist, 1980), maintaining alveolar bone for future
implant placement (Kokich et al., 2011, Fekonja, 2005a).
However, retention of the primary incisor or canine can be
of functional benefit as the primary teeth will maintain the
alveolar bone for orthodontic treatment and future implant
placement (Carter et al., 2003).
C. Auto-transplantation: It can be recommended if a donor
premolar is available, to transplant to the recipient (hy-
podontia) site, especially in cases of multiple missing maxil-
lary incisors (Zachrisson et al,2004). Criteria for auto-trans-
plantation of premolars to missing incisors site (Andreasen
et al., 1990b) are:
• Roots of the donor premolars should be less than ¾
formed.
• Multiple missing incisors.

HYPODONTIA 215
• Procedure is undertaken by skilled surgeons.
• Adequate space in the arch (Zachrisson et al., 2004).
• No jiggling contacts between donor tooth and op-
posing teeth during post-surgical recovery phase
(Andreasen et al., 1990a).
• Use of 3D printed donor tooth to facilitate surgical
procedure.
Advantages of auto-transplantation (Aslan et al., 2010)
These include:
• In growing children, the transplanted tooth main-
tains growth and development of the alveolar ridge,
and also provides a permanent solution to agenesis
of teeth.
Successfully transplanted premolars appear to
continue erupting and aesthetics is good when restored with
porcelain veneer crowns or full porcelain coverage.
D. Space closure: Factors favouring the decision to close the
space when upper lateral incisors are missing are listed in
table 2.
Table 2: Factors favouring the decision to close the space of missing upper lateral incisor
Factors Examples
General factors Patients willing to undergo a possibly longer treatment duration and enameloplasty of the canine
and premolar.
Patients refusing artificial teeth/prosthetic restorations; bridges or partial denture, or implants.
Macro-aesthetic factors Convex facial profile or Class II skeletal and dental relationships.
Bimaxillary protrusion requiring extraction for profile improvement.
Class II malocclusion with redundant overjet.
Mini-aesthetic factors Normal or increased tooth-gingival display during smiling.
Micro-aesthetic factors Small or average sized canine.
Favorable light color of canine.
Adequate attached gingiva on the canine.
Optimum alveolar bone width for canine mesialization.
Intra- and inter-maxillary
factors
Bilateral absence of lateral incisors.
Unilateral agenesis of lateral incisor with a contralateral peg-shaped tooth.
Crowding requiring lower premolar extraction.
Minimal space left for the missing lateral incisors.
Proclined or normally-inclined upper incisors.
Problems and solutions of cuspid substitution
Although cuspid substitution offers several advantages over
space opening, it is associated with some obstacles (Table 3).
Benefits of cuspid substitution
These include:
• Cuspid substitution is considered the least invasive
option when compared to tooth-supported restora-
tions or implant replacement.
• Evidence has shown that implant-supported re-
placement is not immune to complications such as
progressive resorption of the labial cortical plate,
progressive infraocclusion secondary to long-term
facial growth, gingival darkening, gingival recession
as well as the possible need for several years of post-
treatment maintenance and probably bone augmen-
tation (Thilander, 2000, Robertsson and Mohlin,
2000).
• Also, the difficulty of matching natural tooth color
and translucency with an implant-supported pros-
thesis has been reported (Zachrisson et al., 2004,
Kokich and Kinzer, 2005).

HYPODONTIA
216
Table 3: List of potential problems and solutions during canine substitution
Problems Solutions
Size mismatch due to large substituting canines and small premolars. Selective reduction and/or addition
Occlusal interference of the upper canine’s cingulum and the upper
premolar’s palatal cusp with opposing teeth.
Interarch tooth size discrepancy
Lack of canine eminence Hybrid bracket prescription
Wire bending and detailing
Lack of root parallelism between the adjacent teeth subsequent to
space closure
Root resorption subsequent to the contact between the buccal roots
of the premolars and the buccal cortical bone
Improper gingival margin levels of the canines and premolars Hybrid bracket positioning
Wire bending and detailing
Gingivoplasty
Space reopening (relapse) Long-term bonded retainer
Extending retainer from first premolar to first premolar
and supplement with a removable night time retainer
(Zachrisson et al., 2011)
Dark color of the canine Vital bleaching
Thin porcelain veneer
High anterior anchorage demand, especially in Class III cases Protraction facemask
Temporary anchorage devices either alone or as part
of an auxiliary appliance system such as Benefit system
(Wilmes et al., 2015, Amm et al., 2019)
Hybrid bracket prescription
Profile flattening due to excessive uprighting of upper incisors during
space closure
Pulp sensitivity/exposure due to reshaping Adequate cooling & incremental reduction
Fluoride varnish for sensitivity
• It has been proven that the alveolar bone height can
be preserved through the early mesial movement of
the canine (Zachrisson, 2007) with a minimal det-
rimental effect on occlusal function (Nordquist and
McNeill, 1975).
• Not only can cuspid substitution avoid possible im-
plant failures and complications, but it can also re-
duce treatment time and cost with higher patient
• satisfaction compared to prosthetic replacement
(Robertsson and Mohlin, 2000).
• According to Schneider et al. (Schneider et al.,
2016), orthodontists and dentists rank cuspid sub-
stitution and implant-supported replacement as
equally pleasing esthetically, while laypeople prefer
canine substitution (Kokich and Kinzer, 2005).
*Compensated bracket positioning for space closure treat-
ment option
These include:
Compensated occlusal-gingival position of brack-
ets: Two factors affect the choice for vertical canine and
premolar bracket positioning in canine substitution cases;
these are the lip line and the gingival condition (biotype &
probing depth). In cases of a high upper lip line or gummy
smile, the canine can be bonded more gingival to allow its
extrusion, bringing its gingival margin 0.5mm incisal to the
upper central’s, and its reduced incisal edge 0.5-1mm cervi-
cal to that of the central. The first premolar can be bonded
as usual occlusogingivally. A gingivectomy or surgical crown
lengthening is performed to simulate the longer cuspid
crown and provide ideal gingival aesthetics of high, low,
high from central incisors to canine, respectively (Zachris-
son, 2007).

HYPODONTIA 217
Canine and premolar brackets prescription for space closure treatment option
Options for Canines
Bracket* (Torque ˚ / Tip˚) Advantages Disadvantages
Ipsilateral U1 bracket
OTT=ETT (+17˚/+4o)
1. Adequate palatal root torque.
2. Suitable if no mesialization is required.
3. Good control of tip and rotation due to wide
bracket
1. Labial enameloplasty is required
2. Labial offset bend may be required to compensate for
reduced first order depth.
3. Reduced interbracket span; stiffer wire during level-
ing.
4. Unsuitable tip if canine requires mesialization
Swapped U1 bracket
OTT=ETT (+17˚/-4o)
1. Adequate palatal root torque
2. Suitable for moderate bodily mesialization
3. Wide; good rotation & tip control during slid-
ing due to a reduced contact angle.
1. Labial enameloplasty is required
2. Labial offset bend may be required to compensate for
reduced first order depth.
3. Reduced interbracket span; stiffer wire during level-
ing.
Ipsilateral U2 bracket
OTT=ETT (+10˚/ +8˚)
1. Moderate palatal root torque
2. Adequate crown tip if no mesial movement is
required.
3. Adequate bracket offset
1. Additional palatal root torque may be required
2. Labial enameloplasty is required.
3. Unsuitable if canine requires mesialization.
Swapped U2 bracket
OTT (+10˚/ +8˚)
ETT (+10˚/ -8˚)
2. Adequate crown tip if significant mesialization
is required.
3. Adequate bracket offset
2. Labial enameloplasty is required.
Inverted ipsilateral U3
bracket
OTT (-7o /+8o)
ETT (+7o /+8o)
1. Labial enameloplasty is not required before
bonding
2. Adequate tip if no mesial movement is re-
quired.
2. Unsuitable for canine requiring mesialization.
Inverted contralateral
“swapped” U3 bracket
OTT (-7o /+8o)
ETT (+7o /-8o)
bonding
2. Adequate tip if significant mesial movement is
required.
3. The integral hook can be used during mesial-
ization
Inverted ipsilateral U4/5
bracket
OTT (-7˚/0˚)
ETT (+7˚/0˚)
bonding.
2. The integral hook can be used during mesial-
ization
2. Unsuitable tip for canine requiring mesialization or
none.
Ipsilateral L3 brackets
OTT (-6˚/ +3˚)
ETT (+6˚/-3˚)
bonding
2. Adequate tip if slight mesial movement is
required.
2. Unsuitable for canine requiring significant mesializa-
tion or none.
Contralteral L3 bracket
OTT (-6˚/+3˚)
ETT (+6˚/+3˚)
bonding
tion or none.

HYPODONTIA
218
tute the lateral incisors. In this situation, the vertical posi-
tion of brackets should be such that after final reshaping,
the substituted lateral incisors are 0.5 mm shorter than the
substituted central incisors (McDowall et al., 2012).
• Compensated mesiodistal position of brackets for
space closure treatment option: If both the canine
and premolar are to be relocated mesially, a slight
alteration in mesiodistal bracket position may be
necessary; this can be achieved through bonding the
be bonded at the same level as the second premolar
brackets more distally, especially for first premolars
with divergent roots to prevent the buccal root from
moving into the cortical plate, which may slow down
Ipsilateral L4s bracket
OTT (-12˚/+2˚)
ETT (+12˚/-2˚)
required.
bonding
tion or none.
Ipsilateral L5s brackets
OTT (-17˚/+2˚)
ETT (+17˚/-2˚)
required.
bonding
Contralateral L4 bracket
OTT (-12˚/+2˚)
ETT (+12˚/+2˚)
bonding
2. Unsuitable tip for canine requiring mesialization or
none.
Contralateral L5 bracket
OTT (-17˚/+2˚)
ETT (+17˚/+2˚)
bonding
Options for first premolars
Bracket Advantages Disadvantages
Ipsilateral U3s brackets
OTT=ETT (-7˚/+8˚)
1. Adequate buccal root torque
2. Optimum tip if no mesialization required
1. Torque is insufficient if premolar requires intrusion
2. Tip is unsuitable for mesialization.
Ipsilateral U4s brackets
OTT=ETT (-7˚/+0˚)
Adequate buccal root torque 1. Torque is insufficient if premolar requires intrusion
2. Unsuitable tip for premolar requiring mesialization
or not.
Inverted ipsilateral L4s
brackets
OTT (-12˚/+2˚)
ETT (-12˚/-2˚)
1. Adequate buccal root for intrusion cases
required.
1. Excessive buccal root torque (risk of root resorption/
fenestration) if premolar is not intruded.
2. Insufficient tip if significant mesialisation is required
Original Torque and Tip= OTT, Expressed Torque and Tip=ETT; the Torque and Tip is based on MBT prescription.
**In cases where a bracket with an integral hook is used and inverted, undesirable tipping may be expected during mesialization
because the point of force application is further away from the centre of resistance.
Associated side effects include increased tooth sensitivity,
regrowth of part of the excised gums, and gingival recession.
Suppose the probing depth of the first premolar is normal in
the presence of a thin gingival biotype. In that case, it is best
to bond it more occlusal for intrusion and normalisation of
gingival margins. Whereas in case of a low upper lip line or
lack of gingival margin display, the canine bracket can also
be bonded more gingival to bring its reduced incisal edge
0.5mm cervical to the central incisor’s edge, or normally
if a composite build-up or veneer is planned for. The first
premolar should for a group functional occlusion. Another
clinical situation is when central incisors are missin g; lateral
incisors substitute the central incisors, and canines substi-

HYPODONTIA 219
tooth movement and lead to periodontal breakdown
and root resorption. This off-set positioning of the
premolar bracket also helps move its palatal cusp
distally, reducing cuspal interference and improving
aesthetic outcomes. Moreover, the upper first molar
tube is positioned more distally to bring the mesial
cusp inwards for a solid Class II interdigitation if no
extractions are planned in the lower arch.
Compensated axial tip of brackets for space closure treat-
ment option
To achieve proper root parallelism at the agenesis site, the
axial positions of the canine and premolar brackets may also
be modified to produce geometry VI forces that allow appro-
priate final root approximation.
Figure 1: Altering tooth size and shape for optimal canine
substitution
Camouflaging the size and shape of teeth for space closure
treatment option
Agenesis of maxillary lateral incisors may present with nor-
mal or under-sized canines (Mirabella et al., 2012, Bozkaya
et al., 2018). Therefore, the substituted laterals’ optimal size
should be evaluated carefully before and during treatment
to determine the need for and amount of reduction or ad-
dition (Figure 1). Several methods are available, such as the
golden proportions in which the lateral incisor’s mesiodistal
dimension represents 61.8% of the central incisor (Kokich
and Kinzer, 2005). Moreover, if not diminutive, the mesiodis-
tal dimension of the contralateral lateral incisor can also be
used to determine the optimal size of the substituted laterals
supplemented with Bolton’s equation and a diagnostic set-up.
E. Reopen or redistribute space
In summary:
• cent teeth (Asher and Lewis, 1986).
• Consider retaining the primary teeth for preserving
alveolar bone for future placement of implants (Thi-
lander et al., 1994).
• Before the advances in 3D printing and the use of
skeletal anchorage devices, space opening was rec-
ommended in (Paduano et al., 2014):
1. Retruded profiles to improve labial sagittal relationships.
2. Class 3 skeletal cases to prevent reverse overjet.
3. Low angle subjects.
4. Unilateral tooth agenesis to improve the aesthetics of pa-
tients and preserve smile symmetry.
5. Molar Class 1 or class 3 tendency to preserve ideal oc-
clusal anterior and posterior relationships (canine and molar
relationships) so that an Angle Class 1 relationship can be
obtained.
6. Reduced overjet.
7. Increased overbite.

HYPODONTIA
220
8. Cases with large canines.
• The main disadvantage of space opening is the
commitment of a dental prosthesis throughout life
(Carter et al., 2003).
• The benefits of space opening are:
1. Good interocclusal interdigitation can be achieved (Balshi,
1993).
2. Some suggest that the space opening approach is func-
tionally more stable and Ffaster treatment than space closure,
but with no string evidence.
Space opening and prosthetic replacement
Interim prosthesis of a space of a missing tooth
These include:
• During treatment and once the required space has
been achieved, a space maintainer such as an open
coil spring or artificial denture tooth is attached to
the orthodontic archwire. (Savarrio and McIntyre,
2005).
• Thermoplastic retainers or Hawley-type retainers
incorporating prosthetic teeth and wire stops should
be used (Richardson and Russell, 2001).
• Removable partial dentures or bridges: They may be
the final long-term restoration if the patient chooses
not to have a dental implant in the long-term (Rada
et al., 2015).
• Conventional porcelain fused to metal bridges: It
is not recommended in young patients due to the
large amount of tooth reduction required in teeth
with large pulps, so it is only placed after complete
growth. In young patients, the anterior spaces may
be closed and redistributed posteriorly for implant
placement later; in the meanwhile, the posterior
space might be restored with interim bridges or
bonded retainers (Kinzer and Kokich Jr, 2005).
• Bonded orthodontic retainers, fixed resin bonded,
or laboratory composite with fibre-reinforced bridg-
es are recommended for longer interim periods to
reduce root approximation.
• TADs supported prosthesis (Ciarlantini, 2019)
Types of final restorations
1. Removable partial dentures: It is the restoration of choice
if the patient is unwilling to undergo lengthy and costly treat-
ment.
2. Bridges
• It includes adhesive or resin-bonded bridges (RBB),
fibre-reinforced composite bridges (FRCB) and por-
celain fused to metal bridges (PFB).
• The 5 and 10-year survival rate of resin-bonded
bridges (RBB) is 91% and 83%, respectively though
RBBs with zirconia framework or that involving one
tooth showed the greatest survival rate (Thoma et al.,
2017).
• Survival of cantilevered RBB is at least as good as a
fixed design (Spear et al., 1997, Creugers et al., 1992,
Hussey and Linden, 1996, Pröbsfer and Henrich,
1997).
• Survival rate of FRCB was 64% after 5 years, irre-
spective of surface or hybrid retainer. Most failures
were due to fracture of the framework and delami-
nation (van Heumen et al., 2009).
• Porcelain-fused-to-gold bridges have a favourable
long-term survival rate of 68.3% after 20 years. Vi-
tal teeth had about three times higher survival rates
than endodontically treated teeth.
• The main reason for these failures was caries (30%)
(De Backer et al., 2008).
• Osseointegrated dental implants: If a dental implant
is placed in the lateral incisor region, it should be
placed in the correct restoratively determining 3D
position (Yang et al., 2015).
Criteria for implant placement
These include:
• Mesial distal distance: At least 1.5 mm away from
the roots of adjacent teeth. Therefore, a minimum
space of 6 mm mesiodistally is required for implants
of 3.0 mm, as 1.5 mm space should be present on
either side of the dental implant (Kokich, 2004).
• Vertical position: 2 and 3 mm (depending upon the
design of the implant) apical to the anticipated gin-
gival margin of the implant restoration.
• Labio-lingual position: At least 1.5 - 2 mm palatal
to the facial curvature of the arch, or point of emer-
gence at the level of mucosal margin. A space of
1.5mm between the facial surface of the implant and
the buccal cortex
• Before debonding the fixed appliance, an appropri-
ate measure of the inter-coronal/inter-radicular dis-
tances is essential.
Success of dental implants
A systematic review found success of dental implants after 5
years is 95.2%, and after 10yrs is 80%, though complications
occur in 24% of patients; mainly due to biological and techni-
cal factors (Pjetursson et al., 2012b). Clinical presentation of
failed implants are:

HYPODONTIA 221
• Infraposition of single implant restorations
• Peri-implant mucosal recession
• Black triangles
• Marginal bone loss around adjacent teeth and bone
loss buccally to the implants.
• Alteration of the contact point.
Treatment options for absent premolars
Treatment options depend on the amount of crowding:
• If the arch is spaced or aligned, preserve the de-
ciduous teeth, mainly deciduous second molars. If
the second deciduous molar survives until 20 years,
they appear to have a good prognosis for long term
survival (Bjerklin and Bennett, 2000). If lower E is
maintained, its mesiodistal width should be reduced
for optimum occlusion (premolarise).
• In case of crowding, deciduous teeth should be ex-
tracted when appropriate. Extraction of upper E’s in
Class II malocclusion and lower E’s in class 3 mal-
occlusion helps correct the overjet. For maximum
spontaneous space closure, consider extraction of
E’s at 9 years (Lindqvist, 1980). Consider controlled
sectioning of lower E’s to allow bodily space closure
(Hemi-sectioning). It has better success in patients
less than 9 yrs of age. (Valencia et al., 2004)
Evidence summary
• As per the systematic review and meta-analysis,
the prevalence of hypodontia is 6.4%, and it varies
on different continents of the world. (Khalaf et al.,
2014)
• High chances of agenesis of lateral incisor in the
presence of peg laterals on contralateral side (Hua et
al., 2013)
• Space closure is a better option if aesthetics allows
(Qadri et al., 2016, McNeill and Joondeph, 1973)
• Frequent debonding of resin-bonded bridges for
the replacement of missing teeth has been reported
(Thoma et al., 2017)
• Failure of implant prosthesis can be reduced by con-
trolling biological and technical factors (Pjetursson
et al., 2012a).
Exam night review
Hypodontia is the developmental absence of one or more
teeth, excluding third molars (Goodman et al., 1994). Also,
known selective tooth agenesis (STHAG)
Classification
• Hypodontia
Agenesis of 1-6 teeth excluding third molars.
• Oligodontia
Agenesis of more than six teeth, excluding the third molars.
• Anodontia
Complete absence of teeth.
The candidate genes for non-syndromic hypodontia (Vas-
tardis et al., 1996, Lammi et al., 2004, Cobourne, 2007b)
MSX1 and MSX2: MSX1 represents a candidate gene for
both syndromic and non-syndromic hypodontia.
• EDA.
• PAX9.
• AXIN2
Incidence
Type of dentition: The incidence of hypodontia in decidu-
ous teeth is 0.1-0.9 %. In permanent dentition 4-6% exclud-
ing third molars (Grahnén, 1956a).
Ethnicity variation: highest in Africa 13.4%, followed by
Europe 7%. Asian and Australians have the same prevalence
of 6.3%. Gender variation: The incidence is 4.6% in males
and 6.4% in females (Polder et al., 2004). Hypodontia is
more frequently reported in females.
Sequence of hypodontia: The common missing tooth types
in Caucasians are: lower second premolars > upper lateral
incisors > upper second premolars > lower central incisors
(Larmour et al., 2005).
Third molars: These are the most commonly absent teeth
with an incidence of 25-35% (Peck et al., 1996).
Premolars: Premolars can form as late as 9 years of age.
Lower 5’s are the most commonly absent (2.6%), followed
by upper 5’s then 4’s (Wisth et al., 1974). Peck has reported
a 3% incidence of missing second premolars (Peck et al.,
1996).
Maxillary lateral incisors: Absent maxillary lateral incisors
constitute 2% of the population (Peck et al., 1996).
Lower incisors: Caucasians is 0.2% (J Neal and E Bowden,
1988).
Aetiology and theories of hypodontia

HYPODONTIA
222
• Evolutional theory: Decrease ins jaw size and tooth
number
• Anatomical theory: Dental lamina in certain areas
susceptible to environmental factors
• Environmental theory: Chemotherapy, infections,
drugs, toxins, trauma, nutrition
• Genetic factors: Polygenic multifactorial
Features of malocclusion
Skeletal features (depending on the severity of malocclusion)
• Retrognathic and hypoplastic maxilla (Wisth et al.,
1974, Hobkirk et al., 1995).
• Small MMPA and reduced vertical dimensions.
(Taju et al., 2018).
• Low mandibular plane angle is associated with re-
duced lower anterior facial height and protrusive
lips (Chung et al., 2000).
Alveolar features
• Lack of alveolar bone
• There is often a fairly flat palatal vault, resulting in
reduced anchorage capacity of upper removable ap-
pliances, Nance palatal arch, or implant placement.
Occlusal features (Fekonja, 2005b)
• Upright incisors.
• Over-erupted incisors.
• Increased overbite
Dental features
• Delayed and asymmetric eruption of permanent
teeth.
• Prolonged retention of primary teeth (Kurol and
Thilander, 1984).
• Infra-occlusion of primary teeth (Kurol and Thilan-
der, 1984).
• Ectopic eruption or impaction of the adjacent teeth,
particularly maxillary canines.
• Microdontia (Graber, 1978)
• Conical crown. (Brook, 1984)
• Transposition (Peck et al., 1996)
• Enamel hypoplasia.
• Molar taurodontism
• Short roots
• Enamel hypoplasia
• Generalised spacing and rotation of teeth adjacent
to the missing teeth
Complications/difficulties with treatment (Grahnén,
1956b)
• Anchorage difficulties
• Atrophy and loss of bone
• Root parallelism for implants
• Aesthetics
• Risk of relapse, e.g. spaces reopening
• Cost of treatment
• Treatment time may be increased
• Treatment outcome may be compromised
• Common issues faced in treating these patients in-
clude: space management, uprighting and aligning
teeth, management of the deep overbite, and reten-
tion (Carter et al., 2003).
Treatment factors (Hobkirk et al., 1995)
• Age.
• Medical history.
• Patient’s opinion and co-operation.
• Facial profile.
• Smile line.
• Gingival line.
• Malocclusion and extent of hypodontia.
• Intra- and inter-arch relationships
• Dental features size, shape, the colour of the adja-
cent teeth.
• Clinical situation of retained teeth.
Sequence of treatment (Spear et al., 1997)
• Create a diagnostic set-up and Kesling set-up.
• Determine the sequence of orthodontic treatment.
• Building-up malformed teeth and answering the
following questions:
• Where should the maxillary lateral incisor (U2) be
positioned mesiodistally
• Where should U2 be positioned buccolingual:
• Where should U2 be positioned inciso-gingivally?
• Evaluate gingival aesthetic.
• Determine space required by golden proportion,
universal mesiodistal width, contra-lateral tooth size

HYPODONTIA 223
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22
1. Incidence of supernumerary teeth
2. Aetiology of supernumerary teeth
3. Genetic influences
4. Clinical features of supernumerary
teeth
5. Classification of supernumerary teeth
6. Examination of supernumerary tooth
7. Management of supernumerary tooth
8. Detailed management of each type of supernu
merary
9. The recommendations of the Royal College of
Surgeon of England
In this Chapter
Supernumerary Teeth
Written by: Mohammed Almuzian, Haris Khan, Eesha Najam, Lubna Almuzian , Abbas Naseem

SUPERNUMERARY TEETH 229
Supernumerary is ‘tooth’ or a ‘tooth-like’ structure which
develops in addition to the normal number of teeth, also
known as hyperdontia
Incidence of supernumerary teeth
In summary:
• The male to female ratio was found to be 2:1 up to
3:1 in the permanent dentition (Shah et al., 2008,
Fleming et al., 2010).
• There is no sexual dimorphism in primary dentition
(Shah et al., 2008, Fleming et al., 2010).
• Supernumerary teeth are 5-10 times more common
in the maxilla than in the mandible (Alvira-Gonza-
lez and Gay-Escoda, Ata-Ali et al., 2014, Scheiner
and Sampson, 1997).
• The incidence of supernumerary teeth in primary
dentition is 0.06% to 0.8% (Cobourne et al., 2012,
Brook, 1974).
• Supernumerary in the primary dentition is often fol-
lowed by a supernumerary in the permanent denti-
tion (Littlewood and Mitchell, 2019, Lu et al., 2017).
• The incidence of supernumerary teeth in the perma-
nent dentition in the Caucasian population is 1-2%
(Garvey et al., 1999, Shah et al., 2008) of which 80
% are present in the anterior maxilla, mostly in the
central incisor region 51.2% (Di Biase, 1969, Mc-
Beain and Miloro, 2018).
• Supernumerary teeth in the premolar and molar re-
gions occur at the incidence of 10% of all supernu-
merary cases (Hyun et al., 2008).
• Supernumerary teeth can be presented unilater-
ally or bilaterally and can occur individually or in
groups. A meta-analysis found bilateral occurrence
more common in non-syndromic multiple super-
numerary teeth (Alvira-Gonzalez and Gay-Escoda,
2012) however, multiple supernumerary teeth could
be an indicator of an underlying medical disorder
(Subasioglu et al., 2015).
• Supernumerary teeth can occur either as an isolated
trait or as a manifestation of a clinical syndrome
(Shah et al., 2008) Table 1
• In the CLP cases, the prevalence of supernumeraries
is as high as 1.9 to 10%, due to the disruption of the
dental lamina during cleft formation. (Akcam et al.,
2010).
Aetiology of supernumerary teeth
Different theories have been suggested for the aetiology of su-
pernumerary teeth (Garvey et al., 1999). These are:
• Dichotomy: Dichotomy of tooth bud and fragmen-
tation of dental lamina e.g. during cleft formation
(Amarlal and Muthu, 2013).
• Atavistic theory: Supernumerary teeth can also be
the result of the reversion or atavism phenomenon.
Atavism is the reappearance of an ancestral condi-
tion or type or a long-distance heredity or phyloge-
netic reversion. Phylogenetic evolution has resulted
in a reduction in the number and size of teeth. Su-
pernumerary teeth may be an atavistic appearance
of extinct primate teeth in the premolar and incisor
region. (Mallineni, 2014, Primosch, 1981).
• Local, independent or conditioned hyperactivity of
dental lamina: Supernumerary can also result from
disturbances during the initiation and proliferation
stages of dental development and, like tooth agen-
esis, can occur as part of a larger disease process,
syndrome or as an idiopathic finding. (Proffit et al.,
2018).
Genetic influences in the development of supernumerary
teeth
Genetic influence can be appreciated by the fact that:
• 20.5% of patient also had first-degree relatives with
a supernumerary teeth (McBeain and Miloro, 2018),
• Association with specific medical and dental disor-
ders (Rajab and Hamdan, 2002),
• Ethnic variations,
• Sexual dimorphism (Rajab and Hamdan, 2002)
Following patterns of inheritance may be observed: (Fleming
et al., 2010)
• Autosomal dominant with incomplete penetrance
• Sex linked trait
• Autosomal recessive trait with lesser penetrance in
females
Table 1: Syndromes associated with supernumerary teeth
Syndrome
Cleft lip and palate
Cleidocranial dyplasia (gene RUNX2)
Gardner syndrome (gene APC)
Ellis–van Creveld (gene EVC; EVC2)
Incontinentia pigmenti (gene NEMO)
Down’s syndrome and its association with Cleft lip and pal-
ate
Ehlers-Danlos syndrome

SUPERNUMERARY TEETH
230
Clinical features and effects of supernumerary teeth
These include:
• Asymptomatic: supernumerary teeth may remain
unerupted and asymptomatic in the permanent den-
tition, usually detected as a chance finding during
routine radiographic screening.
• Failure of eruption of adjacent permanent teeth:
This is the most common cause of unerupted per-
manent central incisors (Seehra et al.) According to
He et al., 23.1% of patients in the mixed dentition
with supernumerary teeth also have impacted inci-
sors (He et al., 2017). For every increase in one su-
pernumerary tooth, the risk of an impacted incisor
increases by more than double.
• Localised crowding/irregularity or displacement:
This can be caused directly due to the eruption of
a supplemental tooth or indirectly by causing dis-
placements or rotations of adjacent erupted teeth.
• Spacing between erupted teeth: 10% of midline
diastemas are due to supernumeraries. Mesiodens
produces a maxillary midline diastema between the
central incisors.
• Resorption of the roots of teeth adjacent to a super-
numerary tooth, though it is very rare (Hogstrom
and Andersson, 1987)
• Aesthetic impact if the supernumerary teeth erupt.
Supernumerary primary teeth may erupt into good
alignment due to the spaced dentition (Fleming et
al., 2010).
Classification of supernumerary teeth
Supernumerary teeth have been classified in the literature
according to location and morphology, shape, position and
number form. Less common classifications include chronol-
ogy and topography, clinical status, sagittal/vertical positions,
developmental stage, clinical complication and surgical ap-
proach (Amarlal and Muthu, 2013). Different parameters
used to classify supernumerary teeth are as follows (Mal-
lineni, 2014) :
1. Location
• Mesiodens
• Paramolar
• Distomolar
• Parapremolar
2. Morphology
• Conical
• Tuberculate
• Supplemental
• Odontomes
Supplemental supernumerary teeth are further classified into
(Primosch, 1981):
• Supplemental: This may also be termed incisiform
or eumorphic. In this form, shape and size is normal.
• Rudimentary or dysmorphic: There is an abnormal
shape and smaller size in this type. These include
conical, tuberculate, and molariform.
Kalra also classified supernumerary teeth according to mor-
phology and number as an accessory (with abnormal mor-
phology) and supplemental (with morphology similar to nor-
mal teeth) (Kalra et al., 2005)
3. Position
• Buccal
• Palatal
• Transverse
4. Numbers (Garvey et al., 1999)
• Single
• Multiple.
5. Orientation
• Vertical
• Horizontal
• Inverted
Examination of supernumerary tooth
It involves:
1. Visual examination of the sign of a supernumerary tooth,
which includes but is not limited to:
• Erupted supernumerary
• Delayed tooth eruption and asymmetric eruption
• Diastema
• Rotation or abnormal inclination of the adjacent
• Colour change or mobility of the adjacent teeth
2. Clinical examination includes:
• Mobility
• Vitality
• Palpation
3. Radiographic examination
• Occlusal and/or periapical radiographs can be used
to detect the position of an unerupted or supernu-

merary tooth (Garvey et al., 1999, Tsai, 2002, An-
thonappa et al., 2012)
• Parallax technique is used to determine the bucco-
lingual position of unerupted supernumerary teeth.
Parallax techniques include vertical parallax using
an OPG with periapical/ occlusal and horizontal
parallax with two periapical radiographs.
• If calcification is under 30%, the supernumerary
tooth will not be seen on a radiograph. (Southall and
Gravely, 1989)
Management of supernumerary tooth
Treatment depends on several factors, such as the age of the
patient, position of the supernumerary tooth, the potential
effect on adjacent teeth, and the type of the supernumerary
tooth. Treatment options (Chawla and Atack, 2012) are:
1. Extraction of supernumerary teeth is recom-
mended in the following cases:
• Delayed/failure of eruption of central incisors. If suf-
ficient space is available in the arch, removing super-
numerary tooth overlying permanent incisor causes
spontaneous eruption within 16 months in 54-78%
of cases (Mitchell and Bennett, 1992, Witsenburg
and Boering, 1981). Permanent incisors were more
likely to erupt without orthodontic treatment when
the supernumerary teeth were extracted from the
primary dentition than from mixed dentition (Jung
et al., 2016). Maxillary incisors which have been im-
pacted due to obstruction caused by supernumerary
tooth have a better prognosis than the failure of the
eruption caused by other causes. (Betts and Camil-
leri, 1999).
• Altered eruption or displacement of central incisors.
• Associated pathology; follicular enlargement, cystic
formation or root resorption of adjacent teeth.
• Localised crowding.
• Spacing produced between erupted teeth due to su-
pernumerary tooth removal must be performed be-
fore orthodontic alignment to avoid root resorption
of adjacent teeth.
• Presence of supernumerary teeth could compromise
secondary alveolar bone grafting in cleft palate pa-
tients, so their extraction is advised at least a month
before alveolar bone grafting.
• Presence of supernumerary in a potential implant
site may compromise implant placement.
2. Monitoring with a periodic radiographic review (radio-
graph examination should be undertaken 6-9 months apart
following the ALARP rule) is recommended in the following
scenarios:
• Asymptomatic tooth not affecting occlusal relation-
ships of erupted dentition.
• Not associated with pathology.
• No active orthodontic treatment is needed or if
orthodontic treatment is required and supernumer-
ary teeth do not interfere with tooth movement.
• Extraction would compromise the vitality of adja-
cent teeth.
Detailed management of each type of supernumerary
Conical supernumerary
Conical supernumeraries are the most common type of su-
pernumerary tooth in the permanent dentition and consti-
tute 75% of all supernumerary teeth.
In terms of morphology, conical supernumeraries are small
peg-shaped teeth with normal, well-developed roots. They
are occasionally located high and inverted into the palate or
positioned horizontally. Usually, the long axis of the tooth is
normally inclined. May erupt or stay remain impacted.
There are three types of conical supernumeraries according
to the location of the conical supernumerary tooth:
• Mesiodens: Located in the midline of the anterior
maxilla, may cause median diastema. (Primosch,
1981). Prevalence of conical mesiodens ranges from
8 to 34%. (Tay et al., 1984, Bodin et al., 1981)
• Paramolar: Present in the maxillary molar region
and can be buccal, lingual or interproximal to the
second and third molars.
• Distomolar: Located distal to the third molar.
The effect of conical supernumerary on permanent incisors
are:
• Rotation or displacement.
• Little effect on the eruption.
• Risk of cystic formation/resorption is very low (Ty-
rologou et al., 2005).
• Spacing: According to a study by Jung et al., super-
numerary teeth were most frequently observed in
the central incisor region, in the palatal position,
and are inverted. Most commonly conical in shape,
median diastema was the most common complica-
tion. (Jung et al., 2016)
Treatment of conical supernumerary include extraction of
conical supernumeraries (>8 years).
Tuberculate supernumerary
Tuberculate supernumeraries constitute 12% of all super-
numeraries. They usually presented as multicusped, barrel-

SUPERNUMERARY TEETH
232
shaped tooth, with possible invaginations which lack full root
development. These mostly remain unerupted and often oc-
cur in pairs. Usually, any supernumerary that does not fall
into the conical or supplemental supernumerary classifica-
tion is included in this category. (Littlewood and Mitchell,
2019)
Tuberculate supernumeraries are mostly present on the pala-
tal aspect of maxillary permanent central incisors, if the cen-
tral incisor is unerupted, the tuberculate supernumerary is
close / associated with the cingulum of the incisor tooth.
The effect of Tuberculate supernumeraries on permanent in-
cisors are:
• Rotation.
• Frequently associated with delayed eruption or ob-
struction of permanent central incisors. (Foster and
Taylor, 1969).
• Tuberculate are more likely to obstruct than conical
(1:1 compared with 1:5). (Yaqoob et al., 2010).
Treatment of tuberculate supernumerary includes extrac-
tion of tuberculate supernumeraries should be done to allow
eruption of incisors. Spontaneous eruption of previously im-
pacted incisors occurs in only 50% of cases of the extraction
of these teeth.
Supplemental supernumerary teeth
They constitute 7% of all supernumerary teeth and are the
most common supernumerary tooth found in the primary
dentition. They are a duplication of a tooth within a series.
Supplemental supernumerary teeth resemble crown mor-
phology of adjacent tooth, challenging to differentiate from
the normal tooth. Usually, they erupt into the oral cavity
and cause crowding. Supplemental supernumerary teeth are
found at the end of a dental series, and they can be seen in
the incisor, premolar and molar region; for example, an ad-
ditional lateral incisor, second premolar, or fourth molar is a
supplemental tooth.
Treatment of supplemental supernumerary teeth include
extraction of most displaced or deformed tooth to relieve
crowding. Root form must be assessed radiographically be-
fore extraction. 90.4% of supernumerary premolars included
in a study by Martínez-González had a supplementary mor-
phology. (Martinez-Gonzalez et al., 2010). Supernumerary
premolars are usually diagnosed as a chance in radiographic
finding without an associated pathology. However, this study
states mechanical or obstructive pathology was associated
with 2.7% of the premolars and enlargement of the follicular
sac more significant than 3 millimetres was present in 26% of
the sample. In a study by Jung et al., displacement of incisors
was more frequently observed in association with the tuber-
culate or supplemental type of premaxillary supernumerary
teeth. (Jung et al., 2016) The decision to extract a tooth in
the presence of supplemental teeth is made on the best size,
colour, morphologic characteristics, and position related to
the other teeth. The tooth nearest to the planned final posi-
tion should be retained without pathology or differences in
morphology. (Proffit et al., 2018)
Odontomes supernumerary
Odontomes constitute 6% of supernumerary teeth and ac-
count for 65% of all odontogenic tumours in the Caucasian
population. Odontomes are more common in permanent
dentition and are rarely found in the primary dentition (Katz,
1989). They are hamartomatous or developmental malfor-
mations containing enamel, dentine and pulp. There are two
types of Odontomas:
a. Complex Odontomes are large disorganised rounded
masses of dentine, pulp and enamel. They are found in the
posterior jaw, and 50% of complex odontomas interfere with
the eruption of adjacent teeth.
b. Compound Odontoma contain many small separate tooth-
like structures (discrete denticles), each having dentine, pulp
and enamel. They are mostly found in the anterior jaw.
Compound odontomas are four times more common than
complex odontomas. But only 1/3rd of compound odonto-
mas prevent the eruption of adjacent teeth. 71.4% of odon-
tomas in the premaxillary region showed delayed eruption of
the adjacent incisors (Jung et al., 2016).
Evidence summary
In a literature review (Ata-Ali et al., 2014), it is reported that
supernumerary teeth are:
• More frequently found in males in the permeant
dentition.
• More common in anterior maxilla
• More prevalent in the permanent dentition
• Treatment depends upon types, age and associated
complications, like ectopic and delayed eruption,
dental impactions, crowding, spacing and follicular
cyst formation.
A meta-analysis on non-syndromic multiple supernumerary
teeth found: (Alvira-Gonzalez and Gay-Escoda, 2012)
• More often bilateral than unilateral.
• More common in the mandible (The evidence is
multiple supernumeraries).

Exam night review
Tooth/ Tooth-like’ structure develops in addition to the
normal number of teeth.
Incidence
• 5-10 times more common in the maxilla
• Primary dentition → 0.06% to 0.8%
• Permanent dentition → 1-2%
• CLP → 1.9 to 10%
Aetiology
• Dichotomy: Dichotomy of tooth bud and fragmen-
tation of dental lamina.
• Atavistic theory:
• Local, independent or conditioned hyperactivity of
dental lamina.
Clinical features and effect of Supernumerary teeth on
permanent incisors
• Asymptomatic
• Failure of eruption of adjacent permanent teeth.
• Localised crowding/irregularity or displacement
• Spacing between erupted teethResorption of roots
• Aesthetic impact if supernumerary erupts.
Classification of supernumerary teeth
Location
• Mesiodens
• Paramolar
• Distomolar
• Parapremolar
Morphology
• Conical
• Tuberculate
• Supplemental
• Odontomes
Indications for extraction
• Supernumerary tooth overlying permanent incisor
• Associated pathology
• Localised crowding.
• Supernumerary tooth causing Spacing.
• Supernumerary that compromises secondary alveo-
lar bone grafting
• Potential implant site.
Indications for monitoring
• Asymptomatic →not affecting occlusal relationships.
• No pathology.
• No interference in Orthodontic tooth movement.
• Extraction →compromises the vitality of adjacents.

SUPERNUMERARY TEETH
234
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WITSENBURG, B. & BOERING, G. 1981. Eruption of impacted
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ManMaxIncisors2010. pdf.[Accessed June 2012].

23
1. Incidence of unerupted central incisor
2. Aetiology of unerupted central incisor
3. Effects of unerupted central incisor
4. Diagnosis of unerupted central incisor
5. Considerations during treatment planning
6. The correlation between dilacerated and impac
tion of incisors
7. Types of tooth dilacerations
8. Methods for space creation to allow spontane
ous eruption
9. Extraction/removal of physical obstruction
10. Watchful waiting or mechanical traction?
11. Open surgical exposure techniques
12. Closed surgical exposure techniques
13. Open versus closed exposure techniques
14. Surgical extraction and coronectomy
15. Auto-transplantation
16. Advantage of autotransplantation
17. Risks and disadvantage of autotransplantation
18. Factors effecting success of autotransplantation
19. Success rate of autotransplantation
20. Prognosis of autotransplantation
21. Management of ankylosed maxillary incisors
In this Chapter
Impacted Maxillary
Central Incisor
Written by: Mohammed Almuzian, Haris Khan, Abbas Naseem, Lubna Almuzian

IMPACTED MAXILLARY CENTRAL INCISOR 237
Delayed eruption of permanent maxillary incisors can be
defined if any of the following conditions are met (Seehra et
al., 2018a):
• The contralateral maxillary central incisor is delayed
by more than 6 months
• Maxillary incisors remain unerupted more than 1
year, after the lower incisors have erupted.
• Unerupted central incisor with closed root apex.
• Normal teeth eruption sequence is disturbed, for
example lateral incisor have erupted before central
incisor
Incidence of unerupted central incisor
In summary:
• Permanent maxillary central incisors are the third
most commonly impacted tooth after the third per-
manent molars and maxillary canines.
• The incidence of unerupted central incisor is 0.04
-2.6 % (Grover and Lorton, 1985, MacPhee, 1935, Di
Biase, 1969).
• Male to female ratio is 2.7:1 (Bartolo et al., 2010).
• There is frequent association of unerupted central
incisors with other dental anomalies, such as ectopic
teeth, supernumerary teeth and enamel hypoplasia
(Bartolo et al., 2010).
Aetiology of unerupted central incisor
Aetiology is multifactorial with both hereditary and environ-
mental factors involved:
A. Environmental factors
• Early loss of primary teeth with or without loss of
space in the arch.
• Over-retained primary teeth.
• History of previous trauma and subsequent dilac-
eration of permanent incisor, usually labial crown
dilacerations of the incisors.
• Localized pathology (cyst formation)
B. Hereditary factors
• Physical obstruction due to supernumerary teeth
(28-60%) (Tay et al., 1984),
• Cleft lip and palate (Paradowska-Stolarz et al., 2014),
• Association with other syndromes i.e. Cleidocranial
dysplasia (CCD), Gardner’s syndrome (Suri et al.,
2004)
• Abnormal tooth/tissue ratio.
• Gingival fibromatosis.
According to Becker, the aetiology of impacted maxillary
central incisors can also be divided into obstructive or trau-
matic causes (Becker, 2013):
A. Obstructive causes
• Supernumerary teeth
• Odontomas
• Ectopic position of the tooth bud
B. Traumatic causes
• Obstruction due to soft tissue repair and scaring
• Dilaceration
• Arrested root development
• Acute traumatic intrusion (intrusive luxation)
Effects of unerupted central incisor
These include:
• Compromised dentofacial appearance, difficulty in
social interaction and low self-esteem (Shaw et al.,
1991).
• Functional problems including incising food and
speech difficulties, particularly in the pronunciation
of sound ‘s’ (Weinberg, 1968).
Diagnosis of unerupted central incisor
These include:
A. Comprehensive medical and dental history (Seehra et al.,
2018b) is crucial especially for:
• Cleft lip and palate patients,
• Patients with craniofacial syndrome (e.g. Cleidocra-
nial dysostosis (CCD) and Gardner’s syndrome).
• Patient with a history of trauma to primary teeth
B. Clinical examination such as:
1. Palpation to assess the presence of labial or palatal bulgi-
ness and
2. Visual clinical assessment to determine:
• Clinical condition of the retained primary teeth and
the adjacent teeth (colour and mobility)
• Position of adjacent teeth (angulation and inclina-
tion) (Tay et al., 1984)
• Presence of arch length discrepancy, spacing, rota-
tions in the labial segment (Moyers, 1976).
C. Radiographic examination such as:
• Panoramic radiograph.

IMPACTED MAXILLARY CENTRAL INCISOR
238
• Long beam periapical radiograph and/ or upper
standard occlusal (Jacobs, 1999). Most of the cases
require horizontal or vertical parallax to determine
the bucco-lingual position of the unerupted tooth.
• Lateral cephalogram.
• CBCT: If conventional radiographs fail to provide
the required information (root resorption, rota-
tion of teeth), CBCT might be prescribed (Grauwe,
2018).
Considerations during treatment planning
These include:
A. Patient-related factors such as:
• Medical history: Medical conditions can potentially
impact orthodontic and/or surgical treatment plans,
for example, bleeding disorders.
• Age and patients’ compliance: The optimal timing
for intervention is not precise; some recommend an
intervention at the period between 8-9 years (Ley-
land et al., 2006). For cases in which a supernumer-
ary tooth caused an impaction of the maxillary inci-
sors, it is believed that too early intervention might
affect the tooth development (Seehra et al., 2018a).
On the other hand, delayed interception might re-
duce the chance for the spontaneous eruption of the
incisor (Leyland et al., 2006). Some report patient
age as a non-significant factor in determining spon-
taneous eruption (Di Biase, 1971).
• Local factors such as the amount of keratinised gin-
giva
B. Local related factors such as:
• Retained primary teeth: Any retained primary tooth
should be extracted during the surgical exposure of
the impacted tooth.
• Arch length discrepancy, spacing, rotations in the
labial segment (Moyers, 1976)
• Position of the impacted incisor in three planes of
space influences both successful spontaneous erup-
tion and overall treatment duration (Chaushu et al.,
2015). The higher the vertical position, the less likely
the tooth to erupt spontaneously after the obstruc-
tion is removed
• Nature/type of physical obstruction (hard tissue or
soft tissue obstruction) including:
1. Tuberculate supernumerary teeth and odontomas are
more likely to obstruct permanent maxillary incisor eruption
than conical supernumerary teeth (Leyland et al., 2006).
2. One-third of compound and one-half of complex odonto-
mas are associated with failure of eruption of the associated
teeth (Katz, 1989).
• Root formation stage of impacted central incisor:
This factor has a controversial effect but is mainly
related to root dilaceration (Foley, 2004, Di Biase,
1971), (Seehra et al., 2018a) (Leyland et al., 2006)
The correlation between dilacerated and impaction of inci-
sors
These include:
• Mildly dilacerated incisors may be brought into the
line of the arch following exposure and application
of orthodontic traction.
• Potential benefits of aligning an impacted and dilac-
erated incisors are improved dental aesthetics and
psychosocial benefits, and the preservation of the
alveolar bone (Sandler and Reed, 1988).
• It has also been reported that dilacerated permanent
maxillary incisors take a longer time to align suc-
cessfully and have a poorer prognosis for a success-
ful eruption (Becker and Chaushu, 2015).
• The success rate of an impacted dilacerated tooth
alignment mainly depends on the following factors
(Topouzelis et al., 2010):
1. The position and direction of the impacted tooth
2. The degree of root formation
3. The degree and position of dilaceration
4. The availability of space for the impacted tooth.
Types of tooth dilacerations
There are two types of dilacerations, coronal or radicular
(root); the former has a better prognosis than the radicular
type. A tooth with radicular dilacerations, at the cervical
third of the root, close to the alveolar crest combined with
an incomplete root formation, has a good prognosis for orth-
odontic traction. Similarly, radicular dilacerations situated in
the apical third of the root should have a good prognosis; it
may require an apicectomy. The most critical type of dilacera-
tion is one close to the CEJ; the prognosis of the aligned tooth
is extremely poor, which may require extraction.
Methods for space creation to allow spontaneous eruption
According to RCT (Pavoni et al., 2013a), rapid maxillary ex-
pansion following surgical removal of the obstruction is an
effective interceptive method in 82% of the cases. In 39% of
the controlled group, removal of the obstruction alone re-
sulted in an eruption of the impacted incisor. The concern
in this study is the controversial use of rapid expansion at an
early age in the absence of crossbite. In a cohort study by Pa-
voni (Pavoni et al., 2013b), it was reported that teeth erupt

spontaneously after removal of the obstruction when the im-
pacted incisor is at a 30° angle to the midsagittal plane, or
when it is located at the gingival third of the root of the con-
tralaterally erupted tooth. But when the angulation is 30-60°,
and the vertical level is at the middle third of the root of the
contralateral tooth, it is recommended that rapid maxillary
expansion is used to aid spontaneous eruption. On the other
hand, spontaneous eruption chances are minimal once the
angulation exceeds 60° and the tooth is in the apical third of
the adjacent erupted tooth. In such cases, surgical exposure,
removal of obstruction and orthodontic traction are needed.
Extraction/removal of physical obstruction
Extraction of supernumerary teeth is associated with 49-
91% of the spontaneous eruption of the impacted maxillary
incisor (Leyland et al., 2006, Foley, 2004). However, 30-54%
still require surgical intervention (Seehra et al., 2018b). For
patients younger than 9 years with a developing permanent
maxillary incisor, their spontaneous eruption on average can
take up to 9–12 months after the removal of an obstruction
(Pavoni et al., 2013a). Spontaneous eruption time can even
take up to 18 months. For patients younger than 9 years, it is
important to avoid surgical traumatising of the tooth follicle
of the impacted incisor.
There is a lack of evidence whether, at the time of obstruc-
tion removal, the incisor should be exposed or left as such to
allow for spontaneous eruption (Chaushu et al., 2015). For
simplicity, it is possible to summarise the intervention using
two acronyms (Seehra et al., 2018a):
• SET for patient older than 9 years: Space creation,
Extraction of obstruction, and Traction of the im-
pacted tooth mechanically, or
• SEWT for under the age of 9 years: Space creation,
Extraction of obstruction, Watchful waiting for
spontaneous eruption, and Traction of the impacted
tooth mechanically, if fails to erupt spontaneously).
Watchful waiting or mechanical traction?
Recent guidelines recommend watchful waiting for the
spontaneous eruption of the impacted tooth after surgical
removal of the physical obstruction for patients younger
than 9 years of age with under-developed/immature teeth
(Seehra et al., 2018a). Some consider it efficient to bond an
attachment on the impacted tooth at the time of surgical
intervention and obstruction removal even if the root still
developing (under the age of 9 years); the attachment can be
used for orthodontic traction at a later stage if spontaneous
eruption fails, thus avoiding the need for a second surgical
intervention (Seehra et al., 2018b). Surgical exposure and
orthodontic traction of unerupted incisors have a success
rate greater than 90% (Davies et al., 2008).
Open surgical exposure techniques (open eruption)
It involves:
• Simple elliptical incision is rarely used but valuable
in soft tissue impaction
• Surgical window/gingivectomy: A surgical window
or gingivectomy is suggested for shallow, labially po-
sitioned maxillary incisor impactions, close to the
alveolar crest, or a broadband of keratinised tissue
is present (Kokich and Mathews, 1993). A gingivec-
tomy procedure is indicated when one half to 2/3rd
of the crown can be uncovered, leaving at least 3 mm
of an attached gingival collar. In most instances, the
tip of the impacted tooth is near the cementoenamel
junction of the adjacent tooth. This technique is sim-
ple, but it sacrifices the attached gingiva (Kokich and
Mathews, 1993). Gingivectomy is contraindicated if
the cervical-enamel junction of the impacted tooth
is within alveolar mucosa
• Apically repositioning flap is used when there is
a risk of gingival attachment loss (Chaushu et al.,
2009). The main indication for this procedure is
when a labially impacted tooth is situated above the
level of the mucogingival junction but not displaced
mesially or distally. It is used primarily for labial
impactions due to the inability to apically reposi-
tion the palatal field (Vanarsdall and Corn, 1977). It
involves raising a labial mucogingival flap from the
crest of the ridge and re-suturing it at the cervical
aspect, leaving the crown exposed. Mostly a partial
thickness flap is used.
• One of the advantages of apically repositioning flap
is that it increases the amount of attached gingiva
Field (Seehra et al., 2018b). However, it might in-
crease incisor clinical crown length and poor soft
tissue aesthetics (Chaushu et al., 2009).
Closed surgical exposure techniques
It involves:
1. Technique and attachments: In this technique, a full-
thickness (mucoperiosteal) flap is raised with avoidance of
incisor follicle removal, and attachment is bonded on the
exposed incisor, then the flap is sutured into the original
position. Low profile attachment is preferred, which can be
bonded to the palatal surface of the impacted incisor (Seehra
et al., 2018b). An impacted incisor with a thin cortical bone
or bone dehiscence has a high potential for gingival recession
(Vandenberghe et al., 2007)(Almuzian et al., 2015).
2. Mechanical traction: As a general principle, no physi-
cal obstruction by the adjacent root should be present in the
direction of traction; otherwise resorption of the adjacent
roots and/or failure of eruption can occur. For adults or ad-
olescents, mechanical traction to the tooth should be com-

240
menced on the day of surgery. Traction forces should be low
and should not exceed more than 2 ounces or 60 grams (Sukh
et al., 2014). Traction force can be applied through the use
of removable or fixed appliances. The removable appliance
might include magnets embedded in a Hawley appliance or
a modified Hawley appliance with anterior hooks and elas-
tics support. Fixed mechanics can be used such as piggyback
mechanics, TMA fishing rods, mini implants, TPA appliance
with ballista spring, intermaxillary elastics supported by
a lower arch, elastic thread extended to the main archwire,
slingshot mechanics using power chain supported by section-
al or full fixed appliance, etc.
Open versus closed exposure (eruption) techniques
The open exposure approach is associated with a 1.37mm lon-
ger clinical crown, abnormal gingival contour and decreased
bone support with 7.5% less bone support on the mesial side
of the affected tooth than with a closed technique (Chaushu
et al., 2003a, Chaushu et al., 2009). On the other hand, the
close eruption is perceived as better in gingival, periodontal
and pulpal status than open exposure. However, there is no
evidence comparing closed or open eruption techniques for
an impacted maxillary central incisor, though a systematic
review conducted for palatally impacted canine shows low-
quality evidence of no difference between the two techniques
(Parkin et al., 2017).
Surgical extraction of the impacted incisor and coronec-
tomy
Extraction and coronectomy of unerupted incisor can be
considered in the presence of:
• Severe dilaceration or coronal dilaceration
• Ankylosis
• Severe infra-occlusion
• Space closure in the mixed dentition, followed by
space reopening in the permanent dentition to gain
bone volume
Surgical extraction or auto-transplantation
Autotransplantation helps preserve the bone at the extraction
side and stimulate bone growth by the eruption of the trans-
planted tooth.
Autotransplantation of premolars is a viable method for re-
placing maxillary central incisors with an excellent long-term
survival (Stange et al., 2016). Ideally, the lower second pre-
molar can be auto-transplanted at the upper central incisors
position where extractions of the lower arch are indicated for
orthodontic reasons (Kvint et al., 2010). Premolars should be
rotated by 90° to increase the mesiodistal width and improve
gingival aesthetics.
Advantages of autotransplantation
These include:
• Physiological tooth (Czochrowska et al., 2000)
• Maintenance of alveolar bone
• Good long-term survival rates.
Risks and disadvantages of autotransplantation
These include:
• Ankylosis and eruption failure (Yaqoob et al., 2010,
Seehra et al., 2018b)
• Poor morphology
• Requirement of extensive reshaping and restorative
treatment
• Maxillary canine displacement is a common
(Chaushu et al., 2003b)
• Static and dynamic occlusal disturbance due to the
presence of palatal cusp,
• External root resorption.
• Premature loss of a transplanted tooth.
Factors affecting the success of autotransplantation
These include:
1. Root development and status such as:
• 1/3rd to 2/3rd of the root of the donor’s teeth should
be formed. If the root development of donor’s teeth
is more significant than 3/4rd, the root canal of the
teeth should be done within 10 days of transplanta-
tion.
• Atraumatic extraction of donor’s teeth
• Intact periodontium of the donor’s tooth
• Minimum invasive surgery for an impacted tooth
removal.
2. Post-transplantation splinting and stabilisation: After
transplantation, splinting of the transplanted teeth for 7-14
days using bonded flexible wire is essential. Splinting can also
be done with orthodontic brackets if other malocclusion fea-
tures need to be corrected, but appliances should be passive
on the transplanted tooth. If orthodontic brackets are bonded
for splinting, there should be enough gap between the gingiva
and bracket, so the patient can easily clean the area above the
bracket.
Success rate of autotransplantation
The success rate for premolar transplant has been reported
from 81-98% (Kvint et al., 2010, Kristerson and Lagerstrom,
1991, Czochrowska et al., 2000, Andreasen et al., 1990). Only
one study reported a 100% success rate, but only four premo-
lar cases were included in the study (Slagsvold and Bjercke,

1978).
Prognosis of autotransplantation
The prognosis of autotransplantated tooth depends upon:
• Root maturation status,
• Surgical exposure and skills of the surgeon
• Type and height of periodontal attachment
• Surgical treatment duration
• Relative crestal bone height of alveolus
• Preservation of vitality
• Oral hygiene
Management of ankylosed maxillary incisors
Although no evidence is available for ideal management of
ankylosed maxillary incisors, the available options are:
• Periodic follow up with or without build-ups for mi-
nor infra-occlusion
• Surgical luxation of the incisor combined with orth-
odontic traction
• Surgical repositioning (osteotomy of dentoalveolar
segment and repositioning or distraction osteogen-
esis of the segment)
• Extraction followed by space closure
• Extraction followed by prosthetic tooth (implant/
bridge)
• Extraction followed by reimplantation
• For growing patients, decoronation can be consid-
ered to preserve the alveolar bone (Malmgren, 2000)
The recommendations of the Royal College of Surgeon
of England for unerupted incisors with supernumerary
teeth impeding the eruption
Below is a summary of the guideline (Seehra et al., 2018):
a) Children younger than nine years (incomplete root de-
velopment of permanent incisor)
1. Create space if require
2. Maintain the space
3. Remove supernumerary tooth atraumatically
4. Monitor eruption for 18 months with or without mini-
mal soft tissue exposure. If exposed, wait 6 months
5. If spontaneous eruption fails, then expose, bond and
align.
b) Children aged nine years (complete or nearly complete
apex)
• Follow stages 1-3
• Monitor eruption for 12 months
• If spontaneous eruption fails, then expose, bond and
align.
c) Children older than 10 years)
• Follow stages 1-3 o
• Expose, bond, and align
Case Example
Diagnostic summary
H.A a 21 years old healthy male presented with missing up-
per right central incisor on permanent dentition with class
I incisors relationship, on Class I skeletal relationship on
average vertical proportions, complicated by impacted and
ankylosed right maxillary central incisor.
The patients has no facial asymmetry, competent lips, opti-
mal incisor show on smile and rest. Intraorally he had Class
I molars and canine relations bilaterally.
Variable Norms T0
SNA 83° ± 3 ° 80°
SNB 79°± 3 ° 77°
ANB 3°± 2 3°
MMPA 27+5° 24°
FACE HEIGHT
RATIO
55% + 2 56%
SN TO Maxillary
plane
8+3° 8°
Upper incisors to
maxillary plane
109± 5 92°
Lower incisors to
mandibular plane
96°± 5 105
Interincisal angle 135± 10 136°
Wits appraisal 0.mm -1mm
Lower incisor to
Apo line
0-2 mm 1 m m

242
What you would ask in the history assessment?
It is important to undertake a comprehensive history evalua-
tion of any dentofacial trauma along with a detailed descrip-
tion of nature of trauma if possible. Chronological age and
status of eruption at the time of trauma should be identified,
signs and symptom of pain, pus discharge should be noted
as well.
How does the information from the trauma history affect
the long term prognosis of the impacted tooth?
With positive history of intrusive dentoalveolar trauma,
moderate to severe intrusion and obliteration of PDL on
DPT (though poor representative) and/ or ankylosis is
highly likely.
What features you would like to screen using the DPT?
Morphology of the root, obliteration of PDL space, dilacera-
tions of root and proximity of the adjacent teeth and roots.
What other radiographical images might be required?
In addition to digital manual palpation, 2D or 3D radio-
graphical images might be required for localisation of tooth
and assessment of ankylosis.
How to diagnose ankylosis of root of central incisor?
Change in the colour of the tooth, metal sound on percus-
sion, obliteration of PDL space as seen on the radiograph
are suggestive ways of diagnosis, though some claimed that
ankylosis can be confirmed with the use of a high definition
CBCT. Ankylosis can be definitely confirmed at the time of
exposure with assessment of mobility and negative response
to mechanical traction. A recent technique involves the uses
of Doppler system.
How do you plan your anchorage demand in this cases?
Anchorage planning should be in 3 planes of spaces, in this
case, considering position of the impacted incisor, vertical
anchorage using heavy archwire for traction of the impacted
tooth (0.021” x 0.025” S/S, 0.019” x 0.025” S/S, transpalatal
appliance, Nance button appliance or TAD) are recommend-
ed, to avoid bowing of the occlusal plane,
Can the lower arch be utilised to provide vertical anchor-
age?
Yes, box elastics supported with heavy lower archwire
(0.019” x 0.025”) can be utilised to extrude the impacted
tooth. It is essential to bond the lower second molars to
increase vertical anchorage value of lower arch.
Why subluxation is the preferred option over distraction
osteogenesis for ankylosed teeth?
Surgical luxation is relatively less invasive and simple. How-
ever, one of the potential complications secondary to sublux-
ation or distraction osteogenesis are intrusion of adjacent
teeth, inflammation/infection, resorption, ankylosis and
poor gingival contour/margins.
What is the chance spontaneous eruption of central inci-
sor following space creation in this case?
Considering the history of dentoalveolar trauma, oblitera-
tion of PDL space and root developmental stage of the
impacted incisor, spontaneous eruption is highly unlikely.
Does extraction of impacted incisor and space closure an
option in this case?
As the case presented with Class I skeletal basis, Class I
molar and Class I canine relationships, reduced overjet and
in absence of crowding, space closure would be unfavour-
able option.
What type of surgical exposure would be recommended
in this case?
The relationship between the position of incisal edge of the
impacted tooth and the mucogingival junction is the key
variable for decision making, accordingly, closed eruption
technique would be the option of choice.
What retention regime would be suitable for this case?
Fixed flexible bonded retainer supported with night wear of
either Hawley or thermoplastic retainer are recommended.

Exam night review
Incidence: 3rd most commonly impacted tooth.
• Unerupted central incisor is 0.04 -2.6 % (Grover and
Lorton, 1985, MacPhee, 1935, Di Biase, 1969).
• Male to female ratio is 2.7:1 (Bartolo et al., 2010).
Aetiology (Becker, 2013).
• Supernumerary teeth
• Odontomas
• Ectopic position of the tooth bud.
• Obstruction due to soft tissue repair and scaring,
• Dilaceration,
• Arrested root development
• Acute traumatic intrusion (intrusive luxation)
Open surgical exposure techniques (open eruption)
• Simple elliptical incision
• Surgical window/ gingivectomy
• Apically repositioning flap
Advantage of autotransplantation (Czochrowska et al.,
2000):
• Physiological tooth
• Maintenance of alveolar bone
• Good long-term survival rates.
Risks and disadvantages of autotransplantation (Yaqoob
et al., 2010, Seehra et al., 2018b)
• Ankylosis and eruption failure
• Poor morphology
• Needs extensive reshaping and restorative work
• Maxillary canine displacement is a common
(Chaushu et al., 2003b)
• Problem with functional occlusion due to presence
of palatal cusp
• External root resorption
• Premature loss of a transplanted tooth.
Management of ankylosed maxillary incisors
• Periodic follow up with or without build-ups for mi-
nor infra-occlusion,
• Surgical laxation of the incisor combined with orth-
odontic traction,
• Surgical repositioning (osteotomy of dentoalveolar
segment and repositioning or distraction osteogen-
esis of the segment),
• Extraction followed by space closure,
• Extraction followed by Prosthesis (implants),
• Extraction followed by reimplantation, or
• For growing patients, decoronation can be con-
sidered to preserve the alveolar bone (Malmgren,
2000).

244
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24
1. Prevalence and Incidence
2. Development and eruption of maxillary canines
3. Aetiology of impacted canines
4. Recent classification
5. Theories of palatally impacted canines
6. Classification of impacted maxillary canines
7. Consequences of an impacted canine
8. Investigations and diagnosis
9. Magnification technique
10. Parallax Technique
11. Sectors classification
12. Risk factors for resorption of lateral roots
13. Management and treatment
14. Interceptive treatment
15. Guidelines for interceptive treatment
16. Surgical exposure and orthodontic alignment
17. Type of surgical exposure
18. Mechanical eruption of the impacted canine
19. Indications for surgical removal
20. Indication of transalveolar autotransplant
21. Indication of surgical repositioning
22. Causes of poor outcome
23. Impacted mandibular canine
In this Chapter
Impacted Canine
Written by: Mohammed Almuzian, Haris Khan,Maham Munir, Abbas Naseem

IMPACTED CANINE
248
Acanine is considered impacted if:
• It is unerupted after three quarters root develop-
ment (Litsas and Acar, 2011).
• The contralateral tooth has erupted for at least 6
months with complete root formation or
• The canine position is intraosseous at or beyond CS5
or 2 years after adolescent growth spurt or 6 month
after its root completion (Lindauer et al., 1992).
Ectopic or displaced canines (DCs) refers to intraosseous
or infraosseous position of the canine before the expect-
ed time of the eruption.
Prevalence and Incidence
In summary:
• Maxillary canines are developmentally absent in
0.3% of the population (Brin et al., 1986a).
• Mandibular canines are developmentally absent in
0.1% of the population (Littlewood and Mitchell,
2019)
• Maxillary canines are second most frequently im-
pacted teeth after mandibular third molar.
• Impacted canine has incidence of 1.7 to 2% (Ericson
and Kurol, 1988a, Ericson and Kurol, 1986b).
• Palatal impaction of canine is the most common
61%, followed by the impaction within the line of
the arch 34%. While buccal impaction contributes
to 4.5% of the total canine impactions (Stivaros and
Mandall, 2000).
• Unilateral impactions are 4 times more frequent
than bilateral impactions of the canines.
• Female to male ratio is 7:3 (Mossey et al., 1994).
• Dachi and Howell (Dachi and Howell, 1961) showed
that the majority of impacted maxillary canines are
unilateral (92%), and only 8% are bilateral while the
female to male ratio is 2:1.
• Impacted canines are more frequent in in Class II
div.2 malocclusion (Mossey et al., 1994).
Development and eruption of maxillary canines
The calcification of the canine commences at 4-5 months and
completes at 5−6 years of age. Canine development occurs
at high level in the maxilla, lateral to the piriform fossa, and
has the longest path of eruption (22 mm). Canine migrates
forward and downwards to lie buccal and mesial to the apex
of the deciduous canine, then continues to move down and
mesially pushes the distal aspect of the root of the upper lat-
eral incisor creating a physiological median diastema. As the
canine erupts into position, the physiological median dia-
stema closes (Becker, 1978). The maxillary canine should be
palpable in the buccal sulcus by the age of 10 years (Ferguson,
1990).
In general, maxillary canines erupt earlier in females than
in males (Wedl et al., 2004) usually at the age of 11-12 years
while the mandibular canine erupts at the age of 10-11 years
(Littlewood and Mitchell, 2019) (Brin et al., 1986b). It has
been suggested that ectopic canines are associated with de-
layed dental development (Becker and Chaushu, 2000).
Aetiology of impacted canines
The aetiology of impacted canines is multifactorial, both envi-
ronmental and genetic factors are purposed for this anomaly.
• Path of eruption: The long tortuous path of eruption
of upper canine, which is about 22mm, increases the
probability of impaction. Some experts (absence of
strong evidence) stated that impacted canines are
more common in patient with long face.
• Obstruction of the path of eruption: Deciduous ca-
nines can be slightly resistant to resorption prevent-
ing the eruption of permanent canines. The presence
of supernumerary teeth, cyst, fibrous tissue or dense
bone can also obstruct the eruption of the canine
leading to impaction.
• Arch length discrepancy: Crowding or shortening
of the length of the arch can lead to buccal impac-
tion (Jacoby, 1983). Also, in buccal impacted ca-
nines, there is usually reduced maxillary intercanine
width and hyperdivergent skeletal relationships.
• Dental anomalies and canine guidance: The canine,
during its eruption takes guidance from the roots of
lateral incisors. Maxillary lateral incisor anomalies
such as ectopic eruption/ inclination and hypodon-
tia or microdontia increases the chances of deviation
of the canine from its path. A study found that the
incidence of canine impaction is increased to 42.6%
if lateral incisors are small or developmentally ab-
sent (Brin et al., 1986b).
• Genetic background: Palatal impactions are mostly
due to genetic reasons, this is why it is more com-
mon among some ethnic patient’s, females, twins
and in certain families (Jacobs, 1996).
Recent classification of aetiology of maxillary canine im-
paction
These include (Becker and Chaushu, 2015):
1. Local hard tissue obstruction
• Lappin’s theory of over-retained deciduous canine
• Supernumerary teeth and odontoma

IMPACTED CANINE 249
• Abnormal orientation or abnormal root form of the
adjacent first premolar
2. Local pathology
• Chronic periapical granuloma associated with over-
retained deciduous canines
• Displacement of unerupted teeth by radicular cyst
formation
• Hydrostatic pressure provided by dentigerous cyst
• Dentoalveolar trauma
3. Disturbance of the normal development of the incisors.
4. Genetic or hereditary factors
Theories of palatally impacted canines
The guidance theory as described by Dr Becker: It suggests
that the distal aspect of the lateral incisor is the guide for the
canine eruption. Hence, palatally impacted canines were very
closely associated with spaced dentitions, peg -shaped lateral
incisors, microdontia, or congenitally absent lateral incisors.
Approximately half of the cases of palatal impactions that
were diagnosed were associated with anomalous lateral inci-
sors (Becker et al., 1981).
The genetic theory as described by Peck et al in 1994: Accord-
ing to this theory, palatally impacted canines are concomi-
tant with other dental anomalies, such as lateral premolar
hypodontia and peg laterals with strong gender, familial and
population association. However, this theory is not fully clear
in explaining the following controversies:
• Right-left equivalence is the rule in genetics, yet
unilateral canine impaction outnumbers bilateral
occurrence by 2 or 3 to 1.
• The parity of its prevalence in monozygous vs dizy-
gous twins is difficult to explain in genetic terms.
Based on the evidence quoted above, it seems clear that the
determination of the eruption path of the palatal canine is,
for the most part, not under genetic control only. The guid-
ance theory and the genetic theory share the belief that cer-
tain genetic features occur in association with the cause of
palatal displacement of the maxillary canine. These include
small, peg-shaped, and missing lateral incisors, spaced denti-
tions, and late-developing dentitions.
Classification of impacted maxillary canines
These include:
1. Archer classfication
Class I: Impacted canines in the palate which is either hori-
zontal, vertical or semi-vertical.
Class II: Impacted canines located on the labial surface which
is either horizontal, vertical or semi-vertical.
Class III: Impacted canine located labially and palatally with
the crown on one side and the root on the other side
Class IV: Impacted canine located within the alveolar process.
It is usually vertically between the incisor and first premolar
Class V: Impacted canine in edentulous maxilla.
2. Becker Classification (Becker, 2007)
This classification is based on two variables:
• The transverse relationship of the crown of the tooth
to the line of the dental arch, which may be close or
distant (nearer the midline).
• The height of the crown of the tooth in relation to
the occlusal plane, which may be defined as high or
low.
Group Proximity to the
line of the arch
Position in the
maxilla
Group 1 Close Low
Group 2 Close Forward, low, and
mesial to lateral
incisor root.
Group 3 Close High
Group 4 Distant High
Group 5 Canine root apex mesial to that of
lateral incisor or distal to that of first
premolar.
Group 6 Erupting in the line of the arch, in
place of and resorbing the roots of the
incisors.
Sequelae (Consequences) of an impacted canine
These include:
• Labial or lingual mal-positioning of impacted tooth
• Migration of neighbouring teeth and resultant loss
of arch length
• External root resorption of the impacted and neigh-
bouring teeth
• Loss of vitality of the incisors can occur
• Infections and dentigerous cyst formation
• Referred pain
• Damage to adjacent teeth during surgery
• Poor esthetics associated with primary canines
• Ankylosis of impacted canine.

IMPACTED CANINE
250
• Rarely, internal resorption of the canine.
Investigations and diagnosis
It has been suggested that the following clinical signs might
be indicative of canine impaction:
• Delayed eruption of the permanent canine com-
pared to contralateral or the average dental age
• Retention of the deciduous canine beyond 14–15
years of age
• Absence of a normal labial canine bulge or a bulge in
the palatal region of the canine tooth.
• Delayed eruption, distal tipping, or migration
(splaying) of the lateral incisor (Bishara, 1992).
• Loss of vitality and increased mobility of the perma-
nent maxillary lateral incisor and central incisor.
Palpation of the buccal surface of the alveolar process distal
to the lateral incisor from 8 years of age may reveal the posi-
tion of the maxillary canine and has been recommended as
a diagnostic tool; however, lack of positive palpation is only
considered abnormal after the age of 10 years (Kettle, 1957).
Hence, practitioners should suspect ectopia if the canine is
not palpable in the buccal sulcus by the age of 10‑11 years
(Husain et al., 2012). If the canine is not palpable buccally by
9-10 years, then the following investigations should be un-
dertaken (Mittal et al., 2017):
1. Visual clinical assessment inspection of the canine bulge
in which distopalatally inclined lateral incisors may indicate
palatal impaction while mesiolabially inclined lateral incisors
may indicate labial impaction. The colour and mobility of the
deciduous canine should also be assessed.
2. Radiographic assessment using one or a combination of
the following imaging
• Panoramic radiograph (OPG).
• Periapical radiograph.
• Lateral cephalometric radiograph.
• Upper standard occlusal radiograph.
• CBCT or medical CT scans.
Magnification technique
Palatal canines often appear magnified on OPG as the palatal
canine is nearer to the x-ray source and away from the sen-
sor/film (Chaushu et al., 1999). To localise impacted canines
on a single OPG, certain indexes are used:
• Canine-to-incisor index: When the mesiodistal
width of the crown of an unerupted canine (as it
appears and is measured directly on the OPG film)
is 1.15 times larger (i.e., 15% greater) than that of
the adjacent central incisor (the canine-to-incisor
index), then the canine is palatally displaced. This
approach was very reliable in which the canine was
seen on the film to be superimposed on the coronal
or middle portions of the root of the adjacent incisor
(Chaushu et al., 2005).
• Canine-Canine index (CCI): The ratio of the wid-
est mesiodistal dimension of the impacted canine to
that erupted canine (Nagpal et al., 2009). If the im-
pacted canine is palatal, it would be larger than the
erupted contralateral canine.
The problem for diagnosing the buccolingual position of the
impacted canine using a single OPG is that OPG overesti-
mates the angulation and underestimates the proximity to the
midline (Ferguson, 1990). Therefore, the preferred means of
localisation is the parallax technique.
Parallax Technique
Parallax is the apparent displacement of an image of an object
of interest relative to the image of a reference object second-
ary to an actual change in the angulation of the X-ray beam
(Jacobs, 1999). Parallax technique depends on the principle
of tube-shift technique or Clark’s rule or (SLOB) rule: Same
Lingual Opposite Buccal. The image of the tooth that is fur-
ther away from the X-ray tube moves in the same direction
as the tube, whereas that of the tooth closer to the X-ray tube
moves in the opposite direction. There are two types of paral-
lax techniques, horizontal and vertical.
Horizontal parallax can be achieved using:
• Upper standard occlusal and one periapical radio-
graph or
• Two periapical radiographs: It was reported that
92% of the palatal canines could be localised using
two periapical (Ericson S & Kurol J 1987).
Vertical parallax can be obtained using:
• upper standard occlusal radiograph and OPT/ DPT/
OPG
• The upper standard occlusal radiograph has an an-
gulation of 70°‑75° and OPG. OPG and anterior oc-
clusal radiograph are commonly used, giving a 60°
tube shift approximately as the angulation of the X-
ray beam changes in the vertical plane from 8°, for
an OPG, to 60° for an anterior occlusal (Southall and
Gravely, 1987). It has been reported that an increase
in the vertical angulation of the X-ray tube from 60-
65° to 70-75° could increase the effectiveness of the
vertical parallax technique (Jacobs, 1999).
Armstrong and colleagues (Armstrong et al., 2003) showed
that the diagnostic sensitivity for palatally placed canines was
significantly greater using horizontal parallax (88%) com-
pared to vertical parallax (69%). Hence, horizontal parallax is

IMPACTED CANINE 251
superior to vertical parallax in diagnostic accuracy.
Ericson and Kurol sectors’ classification as predictors of
severity of impacted canine
Dr Ericson and Dr Kurol (Ericson and Kurol, 1988b, Ericson
and Kurol, 1988a) were the first to provide a classification for
the position of the canine in both frontal and transverse sec-
tions, utilising both OPG and axial vertex views, to assess the
severity of impaction.
• Sector 1: Medial aspect of the impacted canine
crown in the primary canine region.
• Sector 2: Medial aspect of impacted canine crown
overlapping distal half of the lateral incisor root.
overlapping mesial half of the lateral incisor root.
overlapping distal half of the central incisor root.
overlapping mesial half of the central incisor root or
greater.
Four sector classification by Lindauer (Lindauer et al.,
1992)
These include:
• Sector I: this represents the area distal to the line
tangential to the distal heights of the lateral incisor
crown and root contour.
• Sector II: mesial to the sector I, but distal to the line
bisecting the lateral incisor’s long axis.
• Sector III: mesial to sector II, but distal to the mesial
heights of the contour of the lateral incisor crown
and root.
• Sector IV: all areas mesial to sector III.
based on Lindauer’s method, if the impacted canine
passes the dental midline, it is termed transmigration.
Lindauer’s method reportedly identifies up to 78% of
the impacted canines in sectors II, III, and IV. (Lindau-
er et al., 1992). Dr Olive (Olive, 2005) used Lindauer’s
four sector classification and found that the severity of
impaction by sector was predictive of treatment dura-
tion. According to this study, canines in sectors II and III
emerged after 8 months without any surgical interven-
tion, while those impacted in sector IV emerged after 21
months of treatment.
The three-sector classification by Dr Crescini (Crescini et
al., 2007)
These include:
• Sector I lies between the dental midline and the long
axis of the root of the central incisors.
• Sector II lies distal to sector I and mesial to the long
axis of the root of the lateral incisors.
• Sector III: lies distal to sector II and mesial to the
long axis of the root of the first premolar
It was found that sector 1 required approximately 6 more
weeks of active orthodontic traction than sector 3 impaction.
Sector classification by Stivaros and Mandall
These include :
• Grade 1: No horizontal overlap of the canine crown
with adjacent root. These canines have a good prog-
nosis of treatment, especially for interceptive ortho-
dontics.
• Grade 2: Less than half of the root width of horizon-
tal overlap. Usually, canine horizontal overlap up to
half of the width with the adjacent root generally has
an average prognosis for interceptive orthodontics.
• Grade 3: More than half, but less than the whole root
width
• Grade 4: complete overlap of root width or more.
This grade is usually considered too poor a progno-
sis for interceptive orthodontics.
Alpha angle as predictors of severity of impacted canine
It is the angulation of the long axis of the canine to the upper
midline or midsagittal plane. It is graded as:
• Grade 1: 0–15° (good prognosis for interceptive or-
thodontics)
• Grade 2: 16–30° (average prognosis for interceptive
orthodontics)
• Grade 3: >31° (poor prognosis for interceptive or-
thodontics)
Impacted canine with an alpha angle above 55° is almost al-
ways considered extractions. According to Ericson (Ericson
and Kurol, 1988b), the risk of resorption of the root of the
lateral incisor increases by 50% if the α angle is greater than
25°. Crescini (Crescini et al., 2007) found that an extra week
of active orthodontic traction was required for every 5° of
α-angulation opening. According to a study by Stivaros and
Mandall (Stivaros and Mandall, 2000), orthodontists’ deci-
sions to mechanically erupt or extract an impacted canine,
using radiographic information, depends upon labio-palatal
crown position and angulation to the midline. According to
Bonetti et al. (Alessandri Bonetti et al., 2009), the necessity of
treatment and the degree of treatment difficulty increases as
this angle increases.
β- and Gamma angle as predictors of severity of impacted
canine

IMPACTED CANINE
252
β-angle is the angle between the long axis of the impacted
maxillary canine and the long axis of the adjacent lateral
incisor. According to Ericson (Ericson and Kurol, 1988b),
the difficulty of impacted canine increases when the β angle
is more than 54°. According to Guarnieri (Guarnieri et al.,
2016), the β angle has the most significant influence on the
prediction of root resorption. If the β angle is more than 54°,
the probability of having root resorption is greater than 61%.
On the other hand, the Gamma angle measures the canine
angulation to the occlusal plane (Alqerban et al., 2016).
Distance of the canine’s crown from the occlusal plane as
predictors of severity of impacted canine
The distance (d) represents the distance measured on OPG in
millimetres perpendicularly from the canine cusp tip to the
occlusal plane. The severity of impaction, according to d, was
classified by Vermette (Vermette et al., 1995) into:
• Mild impaction: distance of canine tip to the occlu-
sal plane is less than 12 mm.
• Moderate impaction: distance of canine tip to the
occlusal plane is between 12-15 mm
• Severe impaction: distance of canine tip to the oc-
clusal plane is greater than 15 mm.
Another grading for the vertical canine crown height was
provided by Stivaros and Mandall (Stivaros and Mandall,
2000). The crown of the impacted canine is graded relative to
the adjacent incisor.
• Grade 1: Below the level of the cementoenamel
junction (CEJ).
• Grade 2: Above the CEJ, but less than halfway up the
root. (good prognosis for interceptive orthodontics)
• Grade 3: More than halfway up the root, but less
than the full root length. (Average prognosis for in-
terceptive orthodontics)
• Grade 4: Above the full length of the root. (Poor
prognosis for interceptive orthodontics)
Position of canine root apex anteroposteriorly as predic-
tors of severity of impacted canine
The root apex of canine is graded into (Stivaros and Mandall,
2000):
• Grade 1: Above the region of the canine position
(good prognosis for interceptive orthodontics)
• Grade 2: Above the upper first premolar region (av-
erage prognosis for interceptive orthodontics)
• Grade 3: Above the upper second premolar region
(poor prognosis for interceptive orthodontics)
Incidence of root resorption (RR)
Impaction of canine is associated with a 12% chance of lat-
eral incisors as estimated using plain radiographs (Ericson
and Kurol, 1987). CT (48%) and CBCT (66%) studies showed
a higher value of root resorption (Ericson and Kurol, 2000)
(Walker et al., 2005).
11% of the diagnoses based on OPG images were true posi-
tive, whereas the rest (89%) were false positive. Thus, root
contacts are overestimated when evaluated by OPG (Leuzing-
er et al., 2010). CBCT is more effective in evaluating the cases
that are difficult to diagnose in the initial evaluation using
conventional radiography. According to a systematic review
(Eslami et al., 2017), there is no robust evidence to support
the uses of CBCT as a first-line imaging method for impacted
maxillary canine evaluation. Still, it is indicated that 2D ra-
diography does not provide sufficient information for clini-
cal decision-making, which might change the treatment plan
(Alqerban et al., 2011).
Early radiographic monitoring of patients with aberrant
maxillary canine eruption is needed to detect resorption as
early as possible (Becker and Chaushu, 2005). Root resorp-
tion rarely compromises the longevity of maxillary lateral
incisor (Parker, 1997) despite the increased mobility of teeth
with age (Jonsson et al., 2007).
Risk factors for resorption of lateral roots (Ericson and
Kurol, 1988a)
These include:
• Female to male (5:1 ratio)
• Age less than 14 years: It has been stated that root
resorption of incisors by palatally ectopic canines
rarely starts after 14 years of age, and it occurs most
frequently between 11 and 12 years (Ericson and
Kurol, 1988a)
• Horizontal impaction
• Advanced canine root development
• Dental follicles are wider than 2 mm. However, it
was found that the width of the dental follicle does
not correlate with the resorption (Ericson and Kurol,
1988a, Brusveen et al., 2012).
• The pattern for root resorption associated with im-
pacted maxillary canines is mostly oblique rather
than horizontal (Chaushu et al., 2015).
Management and treatment options for impacted canines
These include:
• No active treatment, only periodic radiographic
monitoring.
• Interceptive treatment by extraction of deciduous
canine.

IMPACTED CANINE 253
• Surgical exposure and orthodontic alignment.
• Surgical removal of the permanent ectopic canine
with orthodontic space closure or prosthetic re-
placement.
• Autotransplantation
Indication for no active treatment
Factors that determine when to consider this option are:
• Satisfactory aesthetics
• Absence of root resorption of adjacent teeth/pathol-
ogy
• Good contact between the lateral incisor and first
premolar
• Deciduous canine has a good prognosis
• Unfavourably impacted canine in sector 4 or 5
However, it is essential to biannually monitor the root resorp-
tion of the lateral incisor, cyst formation and transmigration
using radiographs (Ericson and Kurol, 1988a). There is no
evidence currently available regarding the frequency of ra-
diographic review required in the long-term (Husain et al.,
2010).
Interceptive treatment
Interceptive treatment approaches are indicated in the late
mixed dentition, before CS4, and before the apex of the
displaced canine is completely formed. If not intercepted
with early treatment modalities, palatally displaced canines
(PDCs) progress into palatally impacted canines (PICs) in
two out of three cases.
Interceptive options are:
a. Extraction of deciduous canine
If PDC is present, deciduous canine extraction is usually rec-
ommended to create space or for the displaced canine. Ac-
cording to systematic reviews (Almasoud, 2017, Alyammahi
et al., 2018), the eruption of PDCs can be facilitated by the
extraction of primary canines.
According to Ericson (Ericson and Kurol, 1988a), after ex-
tracting deciduous canines, 78% of palatal canines show nor-
malisation within 1 year (64% in 6 months) in uncrowded
mouths.
Similar findings were reported by Power (Power and Short,
1993), where after extraction of canine, 62% PDC nor-
malised, while 19% showed improvement. If PDC is present,
deciduous canine extraction should be performed as early as
possible (Parkin et al., 2019). The recommended extraction
age of deciduous canine is 10-13 years in uncrowded patients
(Parkin et al., 2012a).
In a prospective RCT, Bazargani (Bazargani et al., 2013)
reported that deciduous canine extraction at the age of 10-
11 years resulted in 67% successful eruption of PDC. This
improvement was shown to be 69% in PDC in another trial
(Naoumova et al., 2014). According to several trials published
by Naoumova and team (Naoumova et al., 2014, Naoumova
et al., 2015, Kjellberg et al., 2015, Naoumova and Kjellberg,
2018), extraction of deciduous canine is the most viable op-
tion for spontaneous correction of PDC.
Guidelines for interceptive extraction of deciduous canine
Ericson and Kurol (Ericson and Kurol, 1986a) suggested that
removing the deciduous canine before the age of 11 years will
normalise the position of the ectopically erupting perma-
nent canines in 91% of the cases if the canine crown is distal
to the midline of the lateral incisor. On the other hand, the
success rate is only 64% if the canine crown is mesial to the
midline of the lateral incisor. According to Naoumova’s trial
(Naoumova, 2014), the points that dictate successful inter-
ceptive treatment for PDCs were the distance of the canine
cusp tip to occlusal plane and distance of the canine cusp
tip-midline while patient age should be less than 11 years.
According to another trial by Naoumova & Kjellberg (Naou-
mova and Kjellberg, 2018), PDC with an alpha angle less than
20 degrees and located in sector 2 can be observed without
prior interceptive extraction. Interceptive extraction should
be done if PDC is located in sector 3 with an alpha angle be-
tween 20 and 30 degrees.
According to the Royal College of Surgeons of England
guidelines on impacted canines (Husain et al., 2012), factors
that determine whether to consider providing interceptive
treatment by removal of the deciduous canine are as follows:
• Age 10‑13 years,
• Absence of crowding.
• The need to maintain space (or even create addi-
tional space) requires consideration. Space mainte-
nance of primary canine (or even additional space
creation) requires careful assessment of the case.
• If radiographic examination reveals no improve-
ment in the ectopic canine’s position 12 months after
extraction of the deciduous canine, alternative treat-
ments should be considered.
b. Other interceptive techniques for impacted or displayed
canine
A longitudinal study by Leonardi showed a 50% success rate
with deciduous canine extraction versus an 80% rate when
headgear was combined with the deciduous canine extrac-
tion (Leonardi et al., 2010). A trial by Baccetti and colleagues
reported 65.2%, 88% and 36% success rates with deciduous
canine extraction, extraction along with cervical pull head-
gear and control (no treatment) respectively (Baccetti et al.,
2008).

IMPACTED CANINE
254
Another trial by Baccetti and colleagues reported 80 % suc-
cess for the rapid maxillary expansion (RME)/transpalatal
arch (TPA)/extraction of primary canine (EC) therapy, 79%
for the TPA/EC therapy, 62.5% for the EC therapy and 28 %
in the control group (Baccetti et al., 2011). Another trial re-
ported 85.7% success when RME was combined with head-
gear, while with headgear alone, the success rate was 82.3%.
The control showed a similar success rate of 36%. Deciduous
canine extraction was not undertaken in this RCT in either
group (Armi et al., 2011).
Surgical exposure and orthodontic alignment
The criteria for surgical exposure are:
• If the canine fails to erupt within 12 months after in-
terceptive treatment or interceptive treatment would
not give the desired results, surgical exposure and
orthodontic alignment is indicated.
• According to Parkin (Parkin et al., 2019), surgical
exposure should be done if the PDC is in medial sec-
tors 3 and 4.
• According to the RCT of Naoumova (Naoumova
and Kjellberg, 2018), a PDC located in sector 4 with
an alpha angle >30 degrees should have immediate
surgical exposure.
• According to another RCT by Naoumova, if the
distance of the canine tip from the occlusal plane ex-
ceeds 5mm and from the midline, it exceeds 6 mm
with patient age greater than 11-12 years, surgical
exposure is desirable (Naoumova, 2014).
Type of surgical exposure
There are two types of surgical exposure for palatal and buc-
cal impacted canines. Still, mainly, the surgical exposure is
usually dictated by the amount of keratinised tissue present
in the impacted area.
Open exposure
This is further subdivided into three subtypes, gingivectomy
(window or open exposure technique) and apical reposition-
ing flap (Warford et al.)(Parkin et al., 2019). In the former
technique, the canine is surgically exposed, a periodontal
dressing (COE-PAK™, GC Corporation, Tokyo, Japan) is
placed for 1 to 2 weeks (without sutures) on the exposed ca-
nine. After 7 days, the dressing is removed, and an attach-
ment is placed on the impacted canine; mechanical traction
is then initiated. Some clinicians prefer spontaneous autocor-
rection of impacted canine after removal of the dressing.
Advantages of open exposure
These include:
• If the tooth is exposed correctly, there is lesser/no
need for re-exposure.
• Easy visualisation enables reasonable control of
force vectors
• Immediate enucleation of the tooth follicle to mini-
mise the risk of root resorption of incisors if present.
Disadvantages of open exposure
These include:
• Possibility of infection and inflammation due to its
invasiveness
• Open exposures cause discomfort (Björksved et al.,
2018). However, the RCT by Dr Parkin (Parkin et
al., 2012b) did not report a significant difference in
patient discomfort between the open and closed sur-
gical techniques.
• Some claimed that this technique is associated with
periodontal problems, gingival rescission and po-
tentially bone loss.
• Re-exposure might be needed if there is inadequate
bone removal at the time of surgery, which will pre-
vent autonomous eruption (Mathews and Kokich,
2013).
• There are always chances (9.6%) of mucosa recover-
ing, especially for deeply placed canines (Parkin et
al., 2019). Naoumova (Naoumova et al., 2018) sug-
gested glass ionomer cement as dressing to avoid
this issue, while Mathews and Kokich (Mathews and
Kokich, 2013) advocated the use of light-cured peri-
odontal dressing (Barricaid™, Dentsply Sirona, PA,
USA).
• A common problem with open exposure is the
bunching of mucosa as the canine is pulled. This re-
sults in a shortening of the clinical crown and makes
extrusion of the canine slow, thus increasing the
treatment time. In such cases, it is recommended to
allow sufficient time for autonomous eruption be-
fore placing an appliance (Parkin et al., 2012b).
Closed surgical exposure
This technique involves the elevation of a mucoperiosteal flap,
removal of sufficient bone to allow exposure of the canine
and its tooth movement, placement of attachment (usually
a bondable attachment with a gold chain), and reposition-
ing the flap often through suturing. A minimum reasonable
amount of dental follicle should be removed to allow place-
ment of attachment. In both open and closed surgical pro-
cedures, bone removal should not be done beyond the CEJ
as it will increase the chances of ankylosis of the impacted
tooth. The close technique is preferred in high impacted ca-
nines, avoiding periodontal packing and open wounds. Trac-
tion should be performed as early as possible (Becker and
Chaushu, 2005).

IMPACTED CANINE 255
Advantages of closed exposure
These include:
(Parkin et al., 2019)
• Minimal chance of infection compared to open ex-
posure technique
• Less bone removal compared to open exposure
technique
• Rapid healing
• Good aesthetic
• No mucosal bunching
Disadvantages of closed exposure
These include:
• There may be some discomfort while applying trac-
tion forces post-surgically.
• As canine is not visualised, there is always difficult
deciding the right direction of traction forces.
• Chances of canine rotation if the attachment is
placed on the palatal surface. Hence, correction of
this rotation can increase the treatment time.
• There would be even chances of pseudo-ankylosis
if the canine moved against the cortical bone. Even
true ankylosis can occur if prolonged forces are ap-
plied.
• Overeruption of canine can result from unsuper-
vised treatment mechanics.
Crescini’s tunnel technique
This technique can be used for both palatal and buccal im-
pacted canines (Crescini et al., 1994). In the “tunnel tech-
nique”, after the extraction of the primary canine, a muco-
periosteal flap is raised on the buccal or palatal aspect to
expose the cusp of the impacted tooth. The empty socket of
the primary tooth is extended to reach the impacted canine
cusp and form an osseous tunnel. A chain is passed through
the tunnel and fixed to a bonded device on the impacted cusp.
The flap is sutured back into its original position. The chain
is used to traction the impacted canine toward the centre of
the alveolar ridge.
Evidence showed that no attachment loss and no recession
were observed at the end of the active therapy (Crescini et
al., 1994) with no significant differences in keratinised tissue
width between test and control teeth at the follow-up exami-
nation (Crescini et al., 1994)
Vestibular incision subperiosteal tunnel access (VISTA) tech-
nique
VISTA technique was introduced by Dr. Zadeh and later
modified and improved by Dr. Chris Chang (Zadeh, 2011).
Two parallel vertical incisions are made to expose and re-
move enough bone to create a tunnel for traction of the tooth.
If necessary, the bone covering the crown of the impacted ca-
nine is removed. A button is bonded to the buccal aspect of
the crown, and elastic chains are connected from the button
to a stainless-steel TAD (2mm in diameter, 12mm in length)
inserted in the infra zygomatic crest (IZC). TAD location
ensures accurate orientation of the force system for optimal
canine traction.
The surgical site is then closed with mono-nylon 6.0 sutures.
After the impacted canine is sufficiently exposed, the chain is
removed, and orthodontic traction of the canine is initiated
(Bariani et al., 2017).
It is claimed that the VISTA technique is more conservative
because it allows horizontal movement of the canine, posi-
tioning it more favourably for traction without compromis-
ing the adjacent teeth (Zadeh, 2011). Space opening with
nickel-titanium coil springs before the initiation of traction
from a low-intensity force (no more than 150g), as well as the
use of a second-generation elastic chain, can provide quick
and efficient mechanics for the eruption of a buccally impact-
ed canine (Zadeh, 2011).
Choices of surgical exposure
Both open and close surgical techniques are usually used for
palatal impacted canines. Apical repositioning flap is rarely
used for palatal impacted canines as there is no deficiency of
keratinised gingiva on the palatal side. There is no reported
difference in aesthetics, cost, periodontal health or patient
satisfaction between the two methods of exposure (Parkin
et al., 2015, Parkin et al., 2013). Similar findings were made
in Cochrane review (Parkin et al., 2017) with low quality of
evidence. According to a systematic review of Sampaziotis
(Sampaziotis et al., 2018), postoperative pain during the first
day is similar between the open and closed surgical exposure
patients. According to a systematic review of Cassina (Cas-
sina et al., 2018), there were no significant differences in ad-
verse effects or patient-oriented outcomes between the two
exposure techniques. Parkin (Parkin et al., 2019) stated that
an open surgical procedure is more beneficial as it helps make
the duration of treatment more predictable and decreases the
time of active traction.
For Buccal impacted canine, both open and closed surgical
procedures can be used depending upon the height of im-
pacted canines. Close surgical technique used mainly for
high impacted canines when the tooth is close to the centre of
the alveolus and crown is apical to the mucogingival junction
(MGJ) (Kokich and Orthopedics, 2004). This technique pro-
vides good aesthetic results for these high canines. Window
technique or gingivectomy is used when the canine crown
is not covered by a significant amount of bone and gingivae.
Also, an adequate amount of keratinised gingival should be

IMPACTED CANINE
256
present. This technique is feasible when after exposing one-
half to two-thirds of the crown, at least 3 mm of attached gin-
giva should be present apical to the exposure; this technique
though simple sacrifices, attached gingiva. Apical reposition-
ing Flap/ ARF (Warford et al.) is used when canine crown is
apical to MGJ and less than 3 mm of attached gingival is pres-
ent. If the canine is overlapping lateral incisor than partial
thickness, ARF should be raised.
Mechanical eruption of the impacted canine
Various techniques can be used for the mechanical eruption
of the impacted canine. These techniques apply an average
force of 20 -70 grams during impacted canine traction (Rob-
erts-Harry and Harradine, 1995, Sange and Thilander, 1990).
Usually, A TPA is used to maintain a transverse dimension,
but other mechanics can be used which do not put a strain on
molars, such as:
• Ballista spring (Jacoby, 1979): The ballista spring is
0.014, 0.016, or 0.018-inch round S/S wire, but TMA
wire can also be used.
• Attraction magnets: One magnet is bonded to ca-
nine while the other magnet can be a part of an up-
per or lower removable appliance. However, there is
toxicity risk due to corrosion, and the force increases
over time as the magnet follow inverse square law
with distance.
• Stainless steel archwire auxiliary: Mostly used for bi-
lateral palatal impacted canine and made from 0.16
SS.
• Cantilever spring or fishing rod: It is mainly made
of 0.017” × 0.025” TMA wire. It can be used for both
buccal and palatal impacted canines.
• TMA box loop: This is made from 0.017” × 0.025”
TMA wire. They are mostly used for buccal impact-
ed canines.
• Removable appliances: Both upper and lower re-
movable appliances can be used for traction of im-
pacted canines. Traction can be done by elastics or
magnets.
• Two archwire techniques or Piggyback mechanics
(Samuels and Rudge, 1997): In this technique, the
main archwire and a lighter auxiliary wire are used
to traction the impacted canine. The main archwire
is usually rectangular and made of stainless steel
0.018-inch or 0.019*0.025-inch, while the lighter
wire is flexible 0.014-inch and made of nickel-titani-
um.
• Nickel-titanium closed-coil spring (Ross, 1999)
• Mandibular or maxillary skeletal anchorage with an
attached elastic or spring (Sinha and Nanda, 1999)
• The K-9 spring (Park et al., 2004) is fabricated from
0.017” × 0.025” TMA wire and engaged in the buccal
segment.
• The monkey hook (Bowman and Carano, 2002):
Monkey hook has an S-shaped design with an open-
loop at both ends.
• Cantilever system (Fischer et al., 2000)
• Double-archwire mechanics using temporary an-
chorage devices (Kim and Gianelly, 2003)
• Auxiliary arm from transpalatal arch (Tausche and
Harzer, 2008)
• Kilroy Spring- Kilroy II Spring (Bowman and Cara-
no, 2003): They are used to apply vertical and lateral
eruptive forces. This spring is given with a fixed ap-
pliance in place.
• Easy-Way-Coil (EWC) system (Schubert, 2008)
Indications for surgical removal of the palatally ectopic
permanent canine
These include:
• If the patient declines active treatment and/or is
happy with their dental appearance.
• The case is not suitable for interceptive orthodon-
tics, and the patient is willing to wear fixed braces
and have good motivation and oral health (Husain
et al., 2012).
• If the canine has close proximity to the midline, has
roots above the apices of neighbouring incisors, or
are horizontally impacted, they are unfavourable for
orthodontic alignment, increasing age chances of
orthodontic alignment decrease as there is increased
risk of ankylosis of the canine(Husain et al., 2012).
• It is usually required when the canine position of
the impacted canine is unfavourable (sector 5 or in-
creased alpha angle or above the apices of the adja-
cent teeth) (Parkin et al., 2019).
• Also, if the canine is rotated, ankylosed or associ-
ated with some pathology, extraction of canine can
be considered instead of extracting other teeth in the
arch.
If the first premolar is considered as a replacement for perma-
nent maxillary canine, then it is recommended to:
• Rotate the premolar mesiopalatally
• Apply buccal root torque to premolar
• Intrude the premolar to match the gingival margins
of the canine followed by occlusal buildup (Thomas
Set al 1998).

IMPACTED CANINE 257
• Grind the palatal cusp of the first premolar
• Aim for group function rather than canine guided
occlusion.
• Veneering the premolar
Indication of transalveolar autotransplant
These include:
• The interceptive option has failed, and the canine
is grossly malposition (Thomas Set al 1998, Moss,
1975).
• When prolonged orthodontic treatment is unac-
ceptable to the patient.
• Ideally, with the open apex at 13-14 years to aid in
maintaining vitality. The optimal development stage
for autotransplantation is when the root is 50-75%
formed (Kristerson, 1985).
• There should be adequate space available for the
canine and sufficient alveolar bone to accept the
transplanted tooth (Husain et al 2016, Husain et al.,
2012).
a. The prognosis should be good for the canine tooth to
be transplanted with no evidence of ankylosis (Husain et al
2016, Husain et al., 2012).
Depending on the stage of root formation (that is, greater
than 3/4 of the root formed), the transplanted canine may
require root canal therapy to be commenced within 10 days
following transplantation (Husain et al., 2012).
Indication of surgical repositioning (McKay, 1978)
These include:
• If the patient is unwilling for complex treatment
• Apex of the canine needs to be in a favourable posi-
tion
• Extensive alveolar and palatal bone is removed, and
canine swung into place about fixed apex.
Causes of poor outcome
These include:
1. Patient-dependent factors such as:
• Abnormal morphology of the impacted tooth and
root
• Dental health and periodontal status of dentition
(Woloshyn et al., 1994)
• Increased Age
• Pathology of the impacted tooth
• Unfavourably impacted tooth position
• Resorption of the root of an adjacent tooth
• Availability of space
• Lack of compliance (e.g., missed appointments, in-
adequate oral hygiene).
2. Orthodontist-dependent factors such as:
• Error in diagnosis in position of canine
• Miss-diagnosis of resorption of the root of an adja-
cent tooth
• Poor anchorage control
• Inefficient biomechanics
3. Surgeon-dependent factors such as:
• Error in diagnosis
• Exposure on the wrong side, or rummaging expo-
sure
• Injury to the impacted tooth
• Injury to the root of an adjacent tooth
• Soft-tissue damage
• Surgery without orthodontic planning.
Impacted mandibular canine
A systematic review (Dalessandri et al., 2017) found the in-
cidence of mandibular canine’s impaction ranges between
0.92 and 5.1%, while that of transmigration ranges from 0.1
to 0.31%.
Although the precise aetiology remains unknown, odon-
tomas (20%), cysts, and lateral incisor anomalies (16%) are
more likely to play a role. The most common treatment strat-
egies are orthodontic traction for if the severity of impaction
is minor or surgical extraction if the impaction is severe. For
transmigrant mandibular canines, if there are no hinders
tooth movement, they can be left with radiographic moni-
toring; otherwise, they need to be extracted in most cases.
According to a systematic review (Dalessandri et al., 2017),
surgical extraction for mandibular impacted canine was the
most favoured option (89 % ), while orthodontic traction is
favored in 20-32 % of the cases with a 17 % failure rate.

IMPACTED CANINE
258
Exam Night Review
Intraosseous position at CS5 or beyond, 2 or more years
after the adolescent growth spurt or 6M after completion.
Prevalence and Incidence:
Incidence of 1.7 to 2%, Palatal impaction 61% followed
by the impaction within the line of the arch 34% while
buccal impaction only contributes 4.5%, Unilateral im-
pactions are 4 times. Female to male ratio 7:3
Aetiology
• Long tortuous path of eruption and developmental-
ly absent/ small lateral incisors (Brin et al., 1986b).
• Deciduous canines are slightly resistant to resorp-
tion.
• Crowding leads to buccal impaction, while palatal
impactions are genetic.
Theories that explain the aetiology of palatally impacted
canines:
• The guidance theory, as described by Becker et al. in
1981.
• The genetic theory, as defined by Peck et al. in 1994
Predictors of severity of impacted canine
Four sector classification of Lindauer (Lindauer et al., 1992)
include:
• Sector I represents the area distal to the line tangen-
tial to the distal heights of the lateral incisor crown
and root contour.
• Sector II: mesial to the sector I, but distal to the line
bisecting the lateral incisor’s long axis.
• Sector III: mesial to sector II, but distal to the mesial
heights of the contour of the lateral incisor crown
and root.
• Sector IV: all areas mesial to sector III.
The three-sector classification by Dr Crescini (Crescini et
al., 2007) are:
• Sector I lies between the dental midline and the long
axis of the toot of the central incisors
• Sector II lies distal to sector I and mesial to the long
axis of the root of the lateral incisors
• Sector III: lies distal to sector II and mesial to the
long axis of the toot of the first premolar
Root resorption of adjacent teeth
• 12% and 48% of lateral incisors as detected using
plain radiographs and CT scan, respectively
• Risk factors for resorption of lateral roots: (Ericson
and Kurol, 1988a)
• Female, age less than 14 years
• Horizontal palatal canines
• Advanced canine root development
• Canine crown medial to the midline of the lateral
incisor
• Size of the follicle
Management and Treatment options
• No active treatment/Leave and observe
• Interceptive treatment:
• Surgical Exposure and Orthodontic alignment
• Surgical removal of the palatally ectopic permanent
canine:
• Transalveolar transplant
• Surgical repositioning
Choices of surgical exposure
For palatal impacted canines
• Both open and closed surgical techniques are used.
• There is no reported difference in aesthetics, cost,
periodontal health or patient satisfaction between
the two methods of exposure (Parkin et al., 2015,
Parkin et al., 2013).
• Similar findings were made in Cochrane review
(Parkin et al., 2017) with low quality of evidence.
For Buccal impacted canine
• For buccal impacted canines, both open and closed
surgical procedures can be used depending upon the
height of impacted canines.
• Close surgical Technique: high impacted canines
when the tooth is close to the centre of alveolus, and
crown is apical to the mucogingival junction (MGJ)
(Kokich and Orthopedics, 2004).
Open Surgical technique (gingivectomy) This technique is
used when the canine crown is not covered by a significant
amount of bone and is apical to MGJ.

IMPACTED CANINE 259
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25
1. Classification of failure of eruption
2. Incidence of PFE
3. Aetiology of PFE
4. Features of PFE
5. Treatment options of the PFE
6. Aetiology of the mechanical failure of eruption
In this Chapter
Primary Failure Of
Eruptions
Written by: Mohammed Almuzian, Haris Khan, Ahmed El-Shanawany, Maha Urooj, Abbas Naseem

PRIMARY FAILURE OF ERUPTION
264
Primary failure of eruption (PFE) is defined as the failure of
a permanent tooth to erupt in the absence of any mechanical
obstruction or systemic condition (OMIM 125350) (Proffit
and Vig, 1981). PFE is attributed to a disturbance in the erup-
tion mechanism, which results in complete failure of erup-
tion (primary retention PFE) or partial failure of eruption
(secondary retention PFE) of a non-ankylosed tooth (Rhoads
et al., 2013).
Classification of failure of eruption
These include (Frazier-Bowers et al., 2007):
1. Primary failure of eruption which is subdivided into two
types, depending on the clinical gradient of the open bite se-
verity:
• Type 1: Progressive anterior to posterior lateral open
bite with lack of all involved teeth eruption poten-
tial. Type 1 appears to occur at a certain chronologi-
cal age.
• Type 2: Teeth distal to the affected tooth have a
smaller lateral open bite but still inadequate erup-
tion. Type 2 correlates to the root developmental
stage.
2. Secondary failure of eruption is an unexplained cessation
in eruption after the tooth has penetrated the gingiva into the
oral cavity (Raghoebar et al., 1991a, Raghoebar et al., 1991b).
3. Mechanical failure of eruption (Schätzle et al.) due to ob-
structed path of eruption with an apparent obstruction.
4. Intermediate failure of eruption (IFE): Unclear if PFE or
MFE due to the patient being too young to diagnose.
Incidence of PFE
In summary:
• The incidence of PFE is 0.6% (Frazier-Bowers et al.,
2016).
• Familial predilection in PFE is found in 10% - 40%
of cases with females and permanent molars most
affected (Rhoads et al., 2013, Ahmad et al., 2006).
• PFE is usually found in Class 3 malocclusion cases.
• There is no difference between maxillary and man-
dibular involvement for PFE.
• PFE mainly occur bilaterally, affecting multiple
teeth.
Aetiology of PFE
These include:
• Mutation in parathyroid hormone receptor 1 gene
(PTH1R, 168468.0012) has been reported as the
main etiological of PFE (Frazier-Bowers et al., 2010).
• Positive family history of gene mutation. PFE is con-
sidered an idiopathic non-syndromic autosomal-
dominant condition (Decker et al., 2008).
Features of PFE
These include:
• Affected teeth are infra-occluded.
• Posterior open bite, however, average vertical pro-
portions.
• Affected teeth are non-responsive to orthodontic
traction after slight movement; affected teeth be-
come ankylosed.
• In PFE, the first permanent molars are constantly
involved with an increased second molar and second
premolar involvement (Rhoads et al., 2013).
• Teeth distally present to the affected tooth are usu-
ally involved.
• Affected teeth have a supracrestal presentation.
• Other dental anomalies can also be present.
• Radiographic features of ankylosis. It is essential to
notice that the sensitivity in diagnosing ankylosis
is 60-70% with CBCT and 30-50% with OPG. This
means that the chance of false-positive results with
OPG is almost 1 in 2 while 1 in 3 with the CBCT
(Ducommun et al., 2017).
Treatment options of the PFEc
These include:
• No treatment for mild cases
• Segmental osteotomy includes corticotomy and seg-
ment distraction to extrude the affected tooth and
alveolar bone to erupt. Some recommend using an
orthodontic bone stretching (Bousquet et al., 2016).
• Restoration of the occlusal table: This may involve
composite build-ups, prosthetic crowns, bridgework
or extraction and implants placement. Restoration of
occlusion need a multi-disciplinary approach, and a
definite treatment plan is based on several erupted
teeth and the vertical functional occlusal height to
be restored (Rhoads et al., 2013).
Aetiology of the mechanical failure of eruption
These include:
1. Local factors due to mucosal barrier such as supernumer-
ary or arch length deficiency as well as severe trauma
2. Systemic factors
• Genetic disorders

PRIMARY FAILURE OF ERUPTION 265
• Cleft lip/ palate
• Cleidocranial dysostosis
• Osteoporosis
• Gardner’s syndrome
• Endocrinal disorders (Hypopituitarism, Hypothy-
roidism and Hypoparathyroidism)
3. Environmental factors such as radiation, nutritional defi-
ciency or drugs therapy like phenytoin
4. Idiopathic factors (PFE, MFE and IFE).
Exam night review
Primary failure of eruption (PFE) is defined as the failure of
a permanent tooth to erupt in the absence of any mechanical
obstruction or systemic condition (OMIM 125350) (Proffit
and Vig, 1981).
Classification of failure of eruption Frazier-Bowers 2007
(Frazier-Bowers et al., 2007)
• Primary failure of eruption
• Secondary failure of eruption
• Mechanical failure of eruption (Schätzle et al.)
• Intermediate failure of eruption (IFE)
Incidence
• The incidence of PFE is 0.6% (Frazier-Bowers et al.,
2016).
• Familial predilection in PFE is found in 10% - 40%
of cases, primarily females and permanent molars
affected (Rhoads et al., 2013, Ahmad et al., 2006).
• PFE is usually found with class 3 malocclusion.
• No difference b/t maxillary and mandibular involve-
ment.
• Bilateral occurrence affecting multiple teeth.
Features of PFE
• Affected teeth are infra-occluded.
• Posterior openbite.
• Non-responsive to orthodontic traction.
• First permanent molars are constantly involved with
increased frequency of second molar and second
premolar involvement (Rhoads et al., 2013).
• Teeth distal to the affected tooth are usually in-
volved.
• Affected teeth have a supracrestal presentation.
• Other dental anomalies may also be present.
Treatment options of the PFE
1. No treatment,
2. Limited orthodontic treatment:
3. Segmental osteotomy.
4. Restoration of the occlusal table.

PRIMARY FAILURE OF ERUPTION
266
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brackets. The European Journal of Orthodontics, 31, 103-107.

26
1. Types of transposition
2. Aetiology of transposition
3. Prevalence of transposition
4. Classification of transposition
5. Treatment planning consideration
6. Maxillary canine and the first premolar
7. Maxillary canine-lateral incisor transposition
8. Maxillary canine-first molar transposition
9. Maxillary incisors transposition
10. Maxillary canine central incisor transposition
11. Mandibular canine lateral incisor transposition
12. Mandibular canine central incisor transposition
13. Intraosseous migration
14. Clinical signs of intraosseous migration
15. Classification of intraosseous migration
In this Chapter
Transposition of teeth
Written by: Mohammed Almuzian, Haris Khan, Abbas Naseem, Muhammad Qasim Saeed

TRANSPOSITION OF TEETH
268
Tooth transposition is the positional interchange of two
adjacent teeth or the eruption of a tooth in a position usu-
ally occupied by a nonadjacent tooth. Transposition is also
known as ‘Transversion’ (Lischer, 1912).
Types of transposition
These include:
• Complete transposition or true transposition in
which both the crown and roots of adjacent teeth
are completely transposed (Shapira and Kuftinec,
1989b).
• Incomplete or pseudo-or partial transposition in-
volves interchange in the positions of adjacent
crowns only, with the roots remaining in their cor-
rect position (Shapira and Kuftinec, 1989b).
Aetiology of transposition
These include:
• Multifactorial, both genetic and environmental
components are involved (Shapira and Kuftinec,
1989b, Peck et al., 1993).
• Strong association with tooth agenesis and peg-
shaped upper lateral incisor teeth.
Prevalence of transposition
According to a meta-analysis, the overall prevalence of trans-
position is 0.33% (Papadopoulos et al., 2010). transposition
mostly affecting upper teeth, 68.5%-76% (Papadopoulos et
al., 2010). Canines are involved in 90% of transposition cases
(Ely et al., 2006b), mostly (88%) unilateral (Ely et al., 2006a).
There is left-sided dominance of transposition though trans-
position has never been reported in both arches simultane-
ously (Shapira and Kuftinec, 1989a) or in deciduous dentition.
Some studies reported female predilection of transposition
though a meta-analysis reported no specific gender predilec-
tion (Papadopoulos et al., 2010).
Classification
Three-part coding was purposed to classify transpositions
(Favot et al., 1986, Peck and Peck, 1995) including:
• Part 1: Jaw of occurrence, coded as either Mx = Maxilla
or Mn = Mandible.
• Part 2: Transposed tooth, coded as - I1 = central incisor,
I2 = lateral incisor, C = canine, P1 = first premolar, P2 =
second premolar, M1 = first molar, M2 = second molar.
• Part 3: Site of transposition, same coding as part 2.
Example: Mx.C.P1 represents transposition of the maxillary
canine to the first premolar position.
The five common types of transpositions which are found in
the upper arch (Peck and Peck, 1995) are:
• Canine–first premolar (Mx.C.P1).
• Canine–lateral incisor (Mx.C.I2).
• Canine on the site of first molar (Mx.C.M1).
• Lateral incisor–central incisor (Mx.I2.I1).
• Canine on the site of the central incisor (Mx.IC.I1).
While the commonest types of transposition which are found
in the lower arch are (Aydin et al., 2004):
• Mandibular lateral incisor-canine transposition (Mn.
I2.C).
• Mandibular canine transmigrated/erupted (Mn.C. tran-
serupted).
Maxillary canine and the first premolar (Mx.C.P1) (Pair,
2011, Peck et al., 1993)
The overall prevalence of Mx.C.P1 is 55%-70%. Bilateral oc-
currence occur in 27% of the cases. The familial occurrence is
11% while the male to female ratio is 1:1.55. The clinical signs
of of Mx.C.P1 (Filhoa et al., 2007) are:
• Canine is usually displaced between the first and
second premolars in a mesiobuccal direction.
• First premolar is frequently distally tipped and dis-
placed in a mesio-palatal direction.
• The primary canine is often present, creating local-
ised crowding.
Treatment options of of Mx.C.P1 are:
1. Interceptive treatment (Peck and Peck, 1995): This in-
volves the extraction of the retained primary tooth between
six and eight years of age. Interceptive treatment can be ad-
opted before transposition is complete, usually around 10
years of age.
2. Definitive treatment such as (Shapira and Kuftinec,
1989a):
• Accepting the transposition.
• Extraction of one of the transposed teeth followed
by orthodontic alignment after opting for either ac-
cepting or correcting the transposition (Filhoa et al.,
2007).
• Correcting the transposition: When repositioning
the transposed teeth, care should be taken to avoid
occlusal interference and root resorption, as well as
bone loss of the buccal bone plate. The palatally dis-
placed premolar should be initially moved palatally
‘palatal parking’ to allow unrestricted buccal move-
ment of the canine toward its normal position. Af-
ter repositioning the canine, the premolar may be

TRANSPOSITION OF TEETH 269
moved back to its normal bucco-palatal work.
Factors affecting treatment decision
These include:
• Facial aesthetics.
• Duration of orthodontic treatment.
• Patient socioeconomic status.
• Risk of caries.
• Root and crown position as they are related to the
risk of root resorption.
• Gingival quality and gingival level of the transposed
teeth.
• Dental morphology and the need for dental reshap-
ing.
• Occlusal and dental crowding.
Maxillary canine-lateral incisor transposition (Mx.C. I2)
(Pair, 2011)
Prevalence of Mx.C. I2: Overall, it ranges from 20%-42%. Bi-
lateral occurrence is 5%. Pseudo-transposition of this type is
more common than true transposition.
Aetiology of of Mx.C. I2: It is usually due to trauma in the
primary dentition and subsequent permanent tooth drift. A
genetic basis for some occurrences cannot be excluded but
is rare (Maia, 2000). Mx.C.I2 is associated with incisor root
dysmorphism (Ghosh, 2018).
Treatment options of of Mx.C. I2 (Lorente et al., 2016) in-
clude:
• Interceptive treatment: Extraction retained primary
tooth.
• Definitive treatment: Accept transposition if com-
plete; correction may involve iatrogenic loss of buc-
cal periodontal attachment of the canine, leading to
a long clinical crown.
Maxillary canine-first molar transposition (Mx.C.M1)
The aetiology of Mx.C.M1 is a rare event usually associat-
ed with the early loss of first or second primary molars. The
clinical sign of of Mx.C.M1 is that the upper canine erupts in
the first permanent molar space, with a mesiopalatal rotation
and palatal displacement. Treatment option of of Mx.C.M1 is
usually accepting the transposition.
Maxillary incisors transposition (Mx.I2.I1)
It is usually due to early life trauma in the incisor region.
Treatment option is accepting the transpositions, with re-
storative camouflage treatment.
Maxillary canine central incisor transposition (Mx.C.I1)
It is a rare type of transpositions (2% of maxillary canine
transpositions) (Ali et al., 2014). Mx.C.I1 develops secondary
to early loss of central incisor (trauma/caries).
Mandibular canine lateral incisor transposition (Mn.I2.C)
It has a significant association with other dental anomalies
cited as evidence for genetic control (Peck et al., 1998).
Mn.I2.C is frequently pseudo-transposed (Brezniak et al.,
1993) and usually associated with peg laterals, hypodontia
and bilateral occurrence.
Treatment options of Mn.I2.C are:
• Extraction of primary teeth.
• Accept transposition.
• Extraction of lateral incisor if crowding is present.
• Restorative camouflage.
Mandibular canine central incisor transposition (Mn.C.I1)
It is a rare type of transposition with uncertain aetiology.
Treatment involves removal of the primary tooth, accept
transposition or de-rotation of the transposed canine and
periodontal surgery.
Intraosseous migration
Ando was the first to use the term transmigration (ANDO et
al., 1964) and defined it as intraosseous migration of a tooth
crossing the midline. Transmigration of unerupted teeth is a
rare phenomenon and occurs more commonly in the lower
jaw (Tarsitano et al., 1971). Transmigration in the upper arch
is considered extremely rare and reported in the form of a few
case reports (Shapira and Kuftinec, 2005, Mittal et al., 2017).
The teeth most commonly involved are canines and second
premolars—the incidence of Mn. C. transerupted is 0.02%
Aetiology of intraosseous migration (Shapira and Kuft-
inec, 2005)
A genetic aetiology is usually cited for this type of transpo-
sition. Other factors cited to contribute to transmigration
are: Trauma, cyst, premature loss of canine, hypodontia,
proclination of the lower incisors, increased axial inclination
of the unerupted canine more than 50 degrees an enlarged
symphyseal cross-sectional area of the chin.
Clinical signs of intraosseous migration
These include:
• Absence of mandibular canines in the dental arch.
• Delayed retention of the mandibular primary ca-
nine.
• Treatment is primarily surgical extraction of the
transmigrated canine.

270
Mupparapu classification for transmigrated mandibular
canine (Mupparapu, 2002)
These include:
• Type 1: Canine positioned mesioangular across the
midline within the jaw bone, labial or lingual to an-
terior teeth, and the crown crossing the midline.
• Type 2: Canine horizontally impacted near the in-
ferior border of the mandible, below the incisor api-
ces.
• Type 3: Canine erupting either mesial or distal to the
opposite canine.
• Type 4: Canine horizontally impacted near the in-
ferior border of the mandible, below the apices of
either premolars or molars on the opposite side.
• Type 5: Canine positioned vertically in the midline
(the long axis of the tooth crossing the midline) ir-
respective of eruption status.
Exam night review
Definition
• Tooth transposition / Transversion is the positional
interchange of two adjacent teeth or the eruption of
a tooth in a position usually occupied by a nonadja-
cent tooth.
• Types of transposition Complete transposition/
true transposition: Crown and roots of adjacent
teeth are completely transposed
• Incomplete or pseudo-or partial transposition: In-
terchange in the positions of adjacent crowns.
Aetiology
• Unclear.
• Multifactorial, both genetic and environmental
components are involved (Shapira and Kuftinec,
1989b, Peck et al., 1993).
• Female predilection (controversial).
• Tooth agenesis.
• Peg-shaped upper lateral incisor teeth.
Prevalence
• According to a meta-analysis, the overall preva-
lence of transposition is 0.33% (Papadopoulos et al.,
2010).
• It mainly affects upper teeth, 68.5%-76% (Papado-
poulos et al., 2010).
• Canines are involved in 90% of transpositions (Ely
et al., 2006b)
• Mostly unilateral, 88% (Ely et al., 2006a).
• Left-sided dominance.
Classification
• Three-part coding was purposed to classify transpo-
sitions (Favot et al., 1986, Peck and Peck, 1995):
Part 1: Jaw of occurrence
Part 2: Transposed tooth
Part 3: Site of transposition
Maxilla / upper arch: In order of most frequent to less
frequent (Peck and Peck, 1995).
• (Mx.C.P1).
• (Mx.C.I2).
• (Mx.C.M1).
• (Mx.I2.I1).
• (Mx.IC.I1).
Maxillary canine and the first premolar (Mx.C.P1) (Pair,
2011, Peck et al., 1993)
Prevalence
• Overall 55%-70%.
• Bilateral occurrence 27%.
Clinical signs (Filhoa et al., 2007)
• Canine is usually displaced between the first and
second premolars in a mesiobuccal direction.
• First premolar is frequently distally tipped and dis-
placed in a mesio-palatal direction.
• The primary canine is often present, creating local-
ised crowding.
Maxillary canine-lateral incisor transposition (Mx.C. I2)
(Pair, 2011)
Prevalence
• 20%-42%.
• Bilateral occurrence: 5%.
Aetiology
• It is usually due to trauma in the primary dentition
and subsequent permanent tooth drift. A genetic ba-
sis for some occurrences cannot be excluded but is
rare (Maia, 2000).
• Mx.C.I2 is associated with incisor root dysmor-
phism (Ghosh, 2018).

TRANSPOSITION OF TEETH 271
References
ALI, Z., JAISINGHANI, A. C., WARING, D. & MALIK, O. 2014.
Transposition of maxillary canine to central incisor site: aetiology,
treatment options and case report. Journal of orthodontics, 41,
233-244.
ANDO, S., AIZAWA, K., NAKASHIMA, T., SANKA, Y., SHIMBO,
K. & KIYOKAWA, K. 1964. Transmigration process of the im-
pacted mandibular cuspid. The Journal of Nihon University School
of Dentistry, 6, 66-71.
AYDIN, U., YILMAZ, H. H. & YILDIRIM, D. 2004. Incidence
of canine impaction and transmigration in a patient population.
Dentomaxillofac Radiol, 33, 164-9.
BREZNIAK, N., BEN-YEHUDA, A. & SHAPIRA, Y. 1993. Unusual
mandibular canine transposition: a case report. American Journal
DE GRAUWE, A., AYAZ, I., SHUJAAT, S., DIMITROV, S., GBA-
DEGBEGNON, L., VANDE VANNET, B. & JACOBS, R. 2019.
CBCT in orthodontics: a systematic review on justification of
CBCT in a paediatric population prior to orthodontic treatment.
Eur J Orthod, 41, 381-389.
ELY, N. J., SHERRIFF, M. & COBOURNE, M. T. 2006a. Dental
transposition as a disorder of genetic origin. Eur J Orthod, 28,
145-51.
ELY, N. J., SHERRIFF, M. & COBOURNE, M. T. 2006b. Dental
transposition as a disorder of genetic origin. The European Journal
FILHOA, L. C., DE ALMEIDA CARDOSOB, M., ANC, T. L. &
BERTOZD, F. A. 2007. Maxillary Canine—First Premolar Transpo-
sition. Angle Orthodontist, 77, 167.
GHOSH, A. 2018. Orthodontic management of maxillary canine
and lateral incisor pseudo-transposition: A 4-year follow-up. Jour-
nal of Indian Orthodontic Society, 52, 137.
LISCHER, B. E. 1912. Principles and methods of orthodontics:
An introductory study of the art for students and practitioners of
dentistry, Lea & Febiger.
LORENTE, T., LORENTE, C., MURRAY, P. G. & LORENTE, P.
2016. Surgical and orthodontic management of maxillary canine-
lateral incisor transpositions. Am J Orthod Dentofacial Orthop,
150, 876-885.
MITTAL, T. K., ATACK, N. E., WILLIAMS, J. C., PURYER, J. S.,
SANDY, J. R. & IRELAND, A. J. 2017. The aberrant second premo-
lar. Orthodontic Update, 10, 96-101.
MUPPARAPU, M. 2002. Patterns of intra-osseous transmigration
and ectopic eruption of mandibular canines: review of literature
and report of nine additional cases. Dentomaxillofacial Radiology,
31, 355-360.
PAIR, J. 2011. Transposition of a maxillary canine and a lateral
incisor and use of cone-beam computed tomography for treat-
ment planning. American Journal of Orthodontics and Dentofacial
PAPADOPOULOS, M. A., CHATZOUDI, M. & KAKLAMANOS,
E. G. 2010. Prevalence of tooth transposition: a meta-analysis. The
Maxillary canine-first molar transposition (Mx.C.M1)
Aetiology
• It is a rare event, usually associated with the early
loss of first or second primary molars.
Clinical signs
• Upper canine erupts in the first permanent molar
space, with a mesiopalatal rotation and palatal dis-
placement.
• Treatment options
• Accept transposition.
intraosseous migration
• Transmigration is defined as the intraosseous mi-
gration of a tooth crossing the midline.
Prevalence
• Mn. C. transerupted is 0.02% (Peck et al., 1998), a
rare phenomenon and occurs more commonly in
the lower jaw (Tarsitano et al., 1971).

272
PAPADOPOULOS, M. A., CHATZOUDI, M. & KARAGIANNIS,
V. 2009. Assessment of characteristic features and dental anomalies
accompanying tooth transposition: a meta-analysis. Am J Orthod
Dentofacial Orthop, 136, 308.e1-10; discussion 308-9.
PECK, L., PECK, S. & ATTIA, Y. 1993. Maxillary canine-first pre-
molar transposition, associated dental anomalies and genetic basis.
PECK, S. & PECK, L. 1995. Classification of maxillary tooth trans-
positions. Am J Orthod Dentofacial Orthop, 107, 505-17.
PECK, S., PECK, L. & KATAJA, M. 1998. Mandibular lateral
incisor-canine transposition, concomitant dental anomalies, and
genetic control. Angle Orthod, 68, 455-66.
SHAPIRA, Y. & KUFTINEC, M. M. 1989a. Maxillary canine-lateral
incisor transposition—orthodontic management. American Jour-
nal of Orthodontics and Dentofacial Orthopedics, 95, 439-444.
SHAPIRA, Y. & KUFTINEC, M. M. 1989b. Tooth transpositions-
-a review of the literature and treatment considerations. Angle
Orthod, 59, 271-6.
SHAPIRA, Y. & KUFTINEC, M. M. 2005. Unusual intraosseous
transmigration of a palatally impacted canine. American journal of
orthodontics and dentofacial orthopedics, 127, 360-363.
TARSITANO, J. J., WOOTEN, J. W. & BURDITT, J. T. 1971. Trans-
migration of nonerupted mandibular canines: report of cases. The
Journal of the American Dental Association, 82, 1395-1397.

27
1. Prevalence of third molar impaction and hy
podontia
2. Aetiology of third molar impaction
3. Classification of third molar impaction
4. Lower incisor crowding and third molar debate
5. Research recommendations
In this Chapter
Third molar and its
impaction
Written by: Mohammed Almuzian, Haris Khan, Muhammad Qasim Saeed

Third molar and its impaction
274
Tooth impaction is a tooth whose root is developed more
than three-quarters of the final root length and whose spon-
taneous eruption is not expected in a reasonable time in its
normal functional position due to the bone, tooth, or fibrous
tissue considered to be an impacted tooth.
Prevalence of third molar impaction and hypodontia
Third molars hypodontia are common among more females;
the females to males ratio are 3:2 (Richardson, 1979). Third
molars impaction is the most among all the teeth. An inci-
dence of 16.7% to 68.6%% has been reported in the literature
(Hashemipour et al., 2013; Bishara and Andreasen, 1983).
Aetiology of third molar impaction
These include:
• Systemic causes include endocranial dysfunction,
developmental diseases and genetic disorders such
as cleidocranial dysostosis and cleft lip/ palate.
• Local causes such as lack of space due to macordon-
tia or under-development mandible (micrognathia),
the excessive density of the bone or the soft tissues
overlying the tooth and ectopic position of the third
molars.
Classification of third molar impaction
These include:
A. According to the available space between the distal
surface of the second molar and the anterior border of the
ascending ramus of the mandible
• Class I: There is sufficient space to accommodate the
mesiodistal diameter of the crown of the third mo-
lar.
• Class II: There is insufficient space to accommodate
the entire mesiodistal dimension, i.e., part of the
crown of the lower third molar is located within the
ramus.
• Class III: There is no space for the third molar to
erupt, i.e. the whole crown of the third molar is lo-
cated within the ramus.
B. According to the relative depth of the tooth within the
bony mandible
• Position A: The highest point of the tooth is at or
above the occlusal plane level of the adjacent tooth.
• Position B: The highest point of the tooth is below
the occlusal plane of the adjacent tooth but above
the cervical margin of the adjacent tooth.
Position C: The highest point of the tooth is below the sec-
ond molar’s cervical margin.
C. According to the inclination of the long axis of the third
molar about the long axis of the second molar
• Vertical Impaction
• Horizontal impaction
• Mesio-angular impaction
• Disto-angular impaction
• Inverted impaction
Lower incisor crowding and third molar debate
Studies relating third molars impaction to lower incisors
crowding. Bergstrom and Jensen’s study (Bergstrom, 1960)
found a greater degree of crowding in both maxilla and
mandible on the side where the third molar was present.
Richardson and Mills(Richardson and Mills, 1990) sug-
gested that the presence of a developing third molar can, in
some cases, cause forward movement of buccal teeth with an
increase in crowding. They proposed that the second molar
extraction effectively reduces the incidence of late lower arch
crowding.
Studies refute the relationship between third molars impac-
tion and lower incisors crowding. Ades and Harradine (Ades
et al., 1990; Harradine et al., 1998) found a lack of corre-
lation between third molars and crowding. In their ran-
domised clinical trial, Harradine and team Field (Harradine
et al., 1998) concluded that the removal of third molars in an
attempt to reduce the degree of late lower incisor crowding
could not be justified.
Research recommendations
Bishara and Andreasen recommendations: Bishara and An-
dreasen (Bishara and Andreasen, 1983) suggest that if only
the mandibular premolars are either missing or extracted,
the lower third molar will, in the end, contact the upper 2nd
molar and prevent the over-eruption of the upper 3rd molar,
hence, lower third molar extraction should be avoided in
these cases for ideal occlusion. Extraction of the third molar
should be avoided in cases with first and second molars of
poor prognosis, particularly in non-growing persons with
Class II malocclusion or open-bite tendencies.
National Institute of Dental Research in 1979 and the
American Association of Oral and Maxillofacial Surgery in
1993 recommendation: There is no evidence to suggest that
a third molar is needed to develop the basal skeletal compo-
nents of the maxilla and mandible. For cases involving dis-
talization, third molar extraction can be considered. There is
little rationale for extracting the lower third solely to avoid
future lower incisor crowding. If adequate room is available
for a third molar eruption, every effort should be made to
bring these teeth into functional occlusion. If extraction of
third molars is indicated, it is preferable not to perform an

Third molar and its impaction 275
enculation (germectomy) procedure.
NICE guidelines for impacted third molar extraction are:
• Prophylactic removal of pathology free impacted
third molars should be avoided.
• Extraction should only be undertaken if there is evi-
dence of pathology. The pathologies of those neces-
sities extraction are similar to those mentioned in
SIGN guidelines.
• Extraction can be undertaken if the patient has se-
vere peritonitis or has more than one minor inci-
dence of pericoronitis.
Exam night review
Prevalence of third molar impaction and hypodontia
• Third molars hypodontia are common among more
females; females to males ratio is 3:2 (Richardson,
1979).
• An incidence of 16.7% to 68.6%% has been reported
in the literature (Hashemipour et al., 2013; Bishara
and Andreasen, 1983).
Classification of third molar impaction
• According to the available space between the distal
surface of the second molar and the anterior border
of the ascending ramus of the mandible
• According to the relative depth of the tooth within
the bony mandible
• According to the inclination of the long axis of the
third molar about the long axis of the second molar
Treatment of impacted third molars
• Observation
• Operculectomy/surgical periodontics
• Coronotomy, Partial excision to avoid damage to the
inferior alveolar nerve (IAN)
• Surgical exposure
• Surgical reimplantation/transplantation
• Surgical removal/excision of tooth/teeth
• In selected cases with the co-operation of experi-
enced orthodontic opinion, active orthodontic ex-
trusion before surgical treatment might be consid-
ered to minimise IAN damage.
Lower incisor crowding and third molar debate
Studies relating third molars impaction to lower incisors
crowding: Bergstrom and Jensen’s study (Bergstrom, 1960)
and Richardson and Mills (Richardson and Mills, 1990)
Studies refute the relationship between third molars impac-
tion and lower incisors crowding: Ades and Harradine (Ades
et al., 1990; Harradine et al., 1998)

Third molar and its impaction
276
References
Ades AG, Joondeph DR, Little RM, et al. (1990) A long-term study
of the relationship of third molars to changes in the mandibular
dental arch. Am J Orthod Dentofacial Orthop 97: 323-335.
Bergstrom KJEOS. (1960) The significance of third molars in the
aetiology of crowding. 84-96.
Bishara SE and Andreasen G. (1983) Third molars: a review. Am J
Orthod 83: 131-137.
Harradine NW, Pearson MH and Toth B. (1998) The effect of ex-
traction of third molars on late lower incisor crowding: a random-
ized controlled trial. Br J Orthod 25: 117-122.
Hashemipour MA, Tahmasbi-Arashlow M and Fahimi-Hanzaei
F. (2013) Incidence of impacted mandibular and maxillary third
molars: a radiographic study in a Southeast Iran population. Med
Oral Patol Oral Cir Bucal 18: e140-145.
Richardson M and Mills K. (1990) Late lower arch crowding: the
effect of second molar extraction. Am J Orthod Dentofacial Orthop
98: 242-246.
Richardson ME. (1979) Late lower arch crowding facial growth or
forward drift? Eur J Orthod 1: 219-225.
Robinson PD. (1994) The impacted lower wisdom tooth: to remove
or to leave alone? Dent Update 21: 245-248.

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