V4- PLANETS OF ORTHODONTICS- Orthodontic Appliances.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., MOrth.RCSEd., FDSRCSEd., MRACDS.Ortho. (Aus-
Dr. Haris Khan
Consultant Orthodontist (Pakistan)
Professor in Orthodontics (CMH Lahore Medical College)
BDS (Pakistan), FCPS Orthodontics (Pakistan), FFDRCS Ortho. (Ire.)
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 IV
Orthodontic Appliances
With

Acknowledgments
This book is the sum and distillate of work which would not have been possible without the support of our fam-
ilies and friends.
Additionally, we would like to thank the rest of contributors of this volume for their time and expertise in updat-
ing individual chapters.
Dedication
I would like to dedicate this book to my mother, Muneba, who was my biggest supporter throughout my
life.
She put me on the path to success and I am forever grateful to her.
Dr M. Almuzian

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 in Orthodontics (Malta)
Dr. Ahmed M. A. Mohamed/ / Specialist Orthodontist (UK/KSA)
Dr. Abu Bker Reda/ Specialist Orthodontist (Egypt)
Dr. Dalia El-Bokle/ Specialist Orthodontist (Egypt)
Dr Lubna Almuzian/ Specialist Paediatric Dentist (UK)
Dr. Muhammad Qasim Saeed / Specialist Orthodontist and Professor in Orthodontics (Pakistan)
Dr. Asma Rafi 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. Farhana Umer / Postgraduate Trainee in Orthodontics (Pakistan)

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: 9798430760410

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 describes briefly the most common orthodontic appliances and their applications in orthodontics.
The theme of this chapter is Mercury as it has been known for a long time because it is visible to the naked eye.
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, it organically grew with input from other authors who
helped in proofreading, summarising the key points of each chapter, and implementing the ‘exam night review’
section. There have been numerous contributors to this book, we seek to acknowledge them, as, without each
contributors efforts, this book would have been nothing more than an interesting idea and a ‘what if’.

Table of Contents
FIXED APPLIANCES IN ORTHODONTICS......... 1
History of orthodontic appliances ...................................... 2
Types of fixed appliances ...................................................... 2
Components of fixed appliances........................................... 2
Classification of the bracket system ..................................... 2
Metal Brackets....................................................................... 3
Stainless steel brackets .......................................................... 3
Titanium brackets................................................................. 4
Cobalt chromium.................................................................. 4
Types of the bracket base....................................................... 4
Bracket base surface area...................................................... 4
Orthodontic brackets recycling............................................ 4
Bracket configurations.......................................................... 5
Bracket prescriptions............................................................ 5
Begg appliance....................................................................... 5
Tip-Edge’ system.................................................................... 6
Self-ligating (SL) appliances.................................................. 6
Factors that have hindered the adoption of self-ligation..... 6
Commonly used SL system................................................... 6
Claimed advantages of SLB .................................................. 6
Disadvantages of SLB ........................................................... 7
Fully-customised brackets..................................................... 7
Aesthetic Brackets ................................................................ 7
Plastic brackets...................................................................... 7
Ceramic brackets................................................................... 7
Disadvantages of ceramic brackets....................................... 8
Types of ceramic brackets..................................................... 8
Polycrystalline brackets......................................................... 8
Monocrystalline brackets...................................................... 8
Table 4: Problems with ceramic brackets.............................. 9
EXAM NIGHT REVIEW...................................................... 10
BEGG ORTHODONTIC MECHANICS................ 13
Begg philosophy.................................................................... 14
Indication of Begg appliance ................................................ 14
Features of Begg appliance.................................................... 14
Begg appliance therapy’s stages and their objectives............ 15
EXAM NIGHT REVIEW ...................................................... 15
REMOVABLE ORTHODONTIC APPLIANCES.... 17
Indications of RAs (Reay and Stephens, 1993)..................... 18
Wires used to construct RAs ................................................ 18
Components of RAs.............................................................. 19
Anchorage component of RAs.............................................. 20
Baseplate................................................................................ 20
Designing RAs....................................................................... 20
Mode of action of RAs........................................................... 21
Checklist while fitting a new RA........................................... 21
Overview Of Clear Aligner Appliances................... 25
General indications of CAT.................................................. 26
General limitations of CAT................................................... 26
Claimed advantages of CAT.................................................. 26
Disadvantages of CAT........................................................... 27
Extraoral appliances ................................................ 31
Classification of Headgear.................................................... 32
Components of the headgear................................................ 32
Types of maxillary retraction headgear................................ 32
Clinical uses of retraction headgear..................................... 32
Factors influencing the effects of the maxillary
retraction headgear............................................................... 33
Fitting of the maxillary retraction headgear........................ 33
Problems and limitations of maxillary retraction
headgear................................................................................. 33
Classification of headgear injury.......................................... 34
Chin cup................................................................................ 34
REVERSE-PULL PROTRACTION FACEMASK
(PFM)..................................................................... 38
Components of PFM............................................................. 39
Types of PFM......................................................................... 39
Indications of PFM................................................................ 39
Effects of PFM........................................................................ 39
Treatment timing for PFM.................................................... 40
Factors influencing the effect of PFM................................... 40
Side effects of PFM therapy .................................................. 41

Predictors of failure of PFM therapy.................................... 41
Skeletal anchorage for maxillary protraction ...................... 41
Instructions to patients wearing PFM ................................. 41
Evidence summary regarding PFM...................................... 42
AUXILIARYARCHES............................................. 45
The Nance appliance.............................................................. 46
The lower lingual arch........................................................... 46
Clinical steps ......................................................................... 46
Indications for transpalatal, Nance and lingual arches........ 46
Applications in vertical direction such as:............................ 47
Common complications........................................................ 47
MOLAR DISTALIZATION APPLIANCES .......... 53
Indications............................................................................. 54
Limitations and contraindications....................................... 54
Decision making.................................................................... 54
Clinical Considerations........................................................ 54
Molar distalization techniques.............................................. 54
Molar distalization techniques.............................................. 58
FINISHING PHASE IN ORTHODONTICS ........ 61
Managing tooth-size discrepancies (TSD) during the
finishing phase ..................................................................... 62
Obtaining an ideal gingival level during the
finishing phase ...................................................................... 62
Assessing the gingival form during the finishing
phase ..................................................................................... 62
Assessing the first order bend during the finishing
phase...................................................................................... 62
Errors in second-order bend during the finishing
phase .................................................................................... 63
Errors in third-order bend during the finishing
phase .................................................................................... 63
Assessing root angulation during the finishing
phase..................................................................................... 63
Control of rebound and posturing during the finishing
phase...................................................................................... 63
Settling of the teeth during the finishing phase.................... 63
EXAM NIGHT REVIEW ...................................................... 63
RETENTION AND STABILITY .......................... 65
Principles of retention........................................................... 66
Factors related to retention................................................... 66
Retention requirements........................................................ 67
Types of orthodontic retainers ............................................. 68
B. Fixed retainers .................................................................. 69
Bonded retainer placement................................................... 70
Retention duration and regimen.......................................... 71
Evidence summary ............................................................... 71
FUNCTIONAL APPLIANCES ................................ 76
History of Functional Appliances......................................... 77
Theories on how functional appliances work....................... 77
Functional appliances and airway......................................... 77
Skeletal modifications by functional appliances.................. 77
Summary of evidence for the effect of functional
appliances.............................................................................. 78
Soft tissue effects of the functional appliance ..................... 78
Indications of a functional appliance ................................... 78
Classification of functional appliances................................. 78
Advantages of removable functional appliances.................. 79
Problems with functional appliances.................................... 79
Class II functional and orthopedic appliances..................... 79
Twin block therapy................................................................ 79
Advantages associated with the twin block ......................... 80
Short-term effects of twin block............................................ 80
Activators appliances............................................................. 80
Activators combined with headgear..................................... 80
Bass appliance........................................................................ 80
Medium opening activator.................................................... 81
Dynamax appliance............................................................... 81
Frankel appliance .................................................................. 81
Herbst Appliance................................................................... 81
Jasper Jumper appliance........................................................ 81
MARA (Mandibular anterior repositioning appliance) ...... 81
Sabbagh universal spring (SUS): .......................................... 82
Twin force bite corrector....................................................... 82
Forsus fatigue resistant device (FRD)................................... 82
Class III correction appliances.............................................. 82
Factors affecting the choice of functional appliances ......... 82
Recommended wear time of removable functional

appliances............................................................................. 83
Timing of intervention using functional appliance therapy
83
Success rates of functional appliances ................................. 83
Stability of treatment secondary to functional appliance
therapy.................................................................................. 83
Early versus late treatment ................................................... 83
Use of functionals in the UK................................................. 84

1
1. History of fixed appliances
2. Types of fixed appliances
3. Components of fixed appliances
4. Classification of the bracket system
5. Bracket base surface area
6. Bracket configurations
7. Standard edgewise and straight wire
8. Bracket prescriptions
9. Begg appliance
10. Tip-Edge’ system
11. Self-ligating (SL) appliances
12. Fully-customised brackets
13. Aesthetic brackets
14. Lingual brackets
15. Problems with ceramic brackets
16. Exam night review
In this chapter
FIXED
APPLIANCES IN
ORTHODONTICS
Written by: Mohammed Almuzian, Haris Khan and Dalia El-
Bokle

fixed appliance in orthodontics
2
Fixed orthodontic appliances are temporarily attached
to the teeth during orthodontic treatment and cannot be
removed by the patient. Fixed appliances apply forces to the
teeth or skeletal structures by interaction with the orthodon-
tic wires and/or auxiliaries.
History of orthodontic appliances
The origin of orthodontic brackets (fixed appliances) can be
matched with the birth of orthodontics and the human de-
sire to align crooked teeth. The first written record correct-
ing crowded or protruded teeth was found 3000 years ago.
Orthodontic appliances to correct malaligned teeth have
been found in Greek, Etruscan and Egyptian artefacts. These
range from crude metal wire loops to metal bands wrapped
around individual teeth in ancient Egyptian mummies.
Pliny the Elder (23-79 AD) was the first to align elongated
teeth mechanically. Pierre Fauchard (1678 –1761), a French
dentist, was the first to make a scientific attempt to align
irregular teeth by an appliance named Bandeau. Edward
Angle introduced a series of fixed appliances like E arch,
Pin and tube appliance, Ribbon arch, and eventually the
Edgewise appliance in 1928 (Angle, 1928). Raymond Begg,
a student of Angle, introduced the Begg appliance in the
1950s. A Straight wire appliance was then introduced by
Larry Andrew (Andrews, 1972). Ronald Roth (1933-2005)
refined Andrew’s straight wire appliance (SWA) in 1976 by
combining extraction and non-extraction series of brackets
to make what is called the “Roth setup.”
The MBT prescription was introduced by Richard McLaugh-
lin, John Bennett and Hugo Trevisi in 1997. The ‘Tip-Edge’
appliance was developed by Peter Kesling (Kesling, 1988)
while the lingual appliance was designed by Kurz in the
1970s (Proffit et al., 2012).
In terms of fixed functional appliances (Herbst appliance)
was first introduced in 1905 (Herbst, 1934) and reintro-
duced in 1979 by Pancherz (Pancherz, 1979). Jasper Jumper
was introduced by James Jasper in 1987.
Table 1 compares removable and fixed orthodontic appli-
ances.
Types of fixed appliances
Fixed appliances can be buccal or lingual. The advantages
and disadvantages of each system are listed in table 2.
Ideal properties of brackets
These include:
• Biocompatible
• Aesthetically pleasing
• Cost-effective
• High modulus of elasticity
• High corrosion resistance
• No magnetic properties
• No friction on bracket/wire interaction
• Correct strength and hardness.
• Resist staining and discoloration in the oral environ-
ment
• Resist plaque accumulation
Table 1: Comparison of fixed and removable appliances
Removable appliances Fixed appliances
Can only produce simple
type of tooth movements
like tipping.
All types of tooth move-
ment in three dimensions
can be achieved.
Root movements cannot be
controlled.
Root movements can be
controlled.
Greater patient compliance
is required.
Less patient compliance is
required.
Oral hygiene is easy to
maintain as the appliance
is removed at the time of
brushing and eating.
Difficult to maintain oral
hygiene.
Good intrinsic anchorage Poor intrinsic anchorage
Low cost Reasonably high cost
Components of fixed appliances
Bracket
Brackets are one of the main components of fixed orth-
odontic appliances that are attached to the crown of teeth,
through which forces are mediated to the teeth by archwires
and auxiliaries to achieve tooth movement.
The most commonly used labial brackets are preadjusted
Edgewise appliances. Customised brackets are primarily
used in lingual bracket system, such as Incognito, but non-
customised brackets like ALIAS by Ormco are also available.
Classification of the bracket system
1. On the basis of material type such as:
• Metal
• Plastic
• Ceramic
• Zirconium
2. On the basis of morphology such as:

fixed appliances in orthodontics 3
Table 2: The advantages and disadvantages of fixed appliance system.
Buccal fixed appliances
Advantages Disadvantages
• Easy access and work for the clinician.
• Reduced chair-side time.
• Excellent finishing and detailing.
• Poor aesthetics.
• Increased chances of visible decalcification.
Lingual fixed appliances
• Good aesthetics (Wiechmann D Nes-
bit L 2007, Russell, 2005).
• Less visible decalcification (Wiech-
mann D Nesbit L 2007, Russell, 2005).
• Upper lingual brackets act as bite
blocks and help in opening the bite
(Singh and Cox, 2011).
• Arch expansion is easier with lingual
appliances.
• Impact on speech
• Difficult to maintain good oral hygiene (Khattab et al., 2013).
• Difficult access for the orthodontist.
• Increased working time.
• Possible soft tissue trauma.
• Short inter-bracket span leading to high force.
• Customised appliances are needed, hence, they are more costly.
• Difficulty in finishing and detailing (Singh and Cox, 2011).
• Mostly do not work well with orthognathic surgical cases.
• Needs indirect bonding.
• Siamese.
• Mini-twin.
• Single-wing e.g., Attract.
• Self-ligating e.g., Damon, In-ovation R, Smartclip.
• Tip-edge.
3. Based on slot size such as:
• 0.018” x 0.028”
• 0.022” x 0.028”
• 0.022” x 0.030”
4. On the basis of method of manufacturing (Matasa,
1992) such as:
• Cast (soft) - may distort on debonding or in deep
bite cases.
• Milled (hard).
• Metal injection moulded (MIM).
• Sintered.
Metal Brackets
These include:
• Stainless steel brackets
• Titanium brackets
• Cobalt chromium brackets
• Precious metal brackets
Stainless steel brackets
Different stainless steel (SS) based orthodontic brackets are
used in contemporary orthodontics including:
1. Austenitic stainless-steel (300 series) is one of the most
popular types of SS alloy used in orthodontics as a bracket
and wire material due to its good corrosion resistance,
excellent formability and low cost compared to other types
of SS. The standard orthodontic twin brackets are usually
manufactured from austenitic type 302, 303SE ,303L ,304
,304L,316 ,316L and 318 with 304 L and 316 L are the mostly
used materials. The L designation refers to lower carbon
contents of steel. The lower carbon contents in SS eliminate
harmful carbide precipitation, thus, decreasing corrosion
susceptibility, but low carbon steel decreases strength. 316
SS and 316-L SS are used where higher corrosion resistance,
especially to chloride, is required. 316 SS is used more
commonly for making base components and, because of
increased corrosion resistance, has been shown to release
less nickel. Austenitic SS is given an AISI number (American

4
Iron and Steel Institute). Low numbers have little additional
alloy metal and are soft in nature. Most brackets are AISI
304 milled, having the following composition, Fe 71%, Ni
8%, Cr 18%, C<0.2%. Some brackets are also made from
AISI 316. These brackets are casted as AISI 316 as it is too
hard to be milled. The main disadvantage of SS is the poten-
tial to cause a nickel allergy (BOS 2012).
2. Super austenitic SS: Super SS is defined as SS with a pit-
ting resistance equivalent value of 40. Super-SS has higher
molybdenum and nitrogen content than conventional SS.
Super SS show good frictional properties, higher resistance
to chloride pitting and crevice corrosion. Super SS has only
been used for in-vitro studies.
3. Precipitation-hardening (PH) martensitic SS (17-4 PH
or S17400): This form of SS has corrosion resistance equal
to austenitic stainless 304 but has better strength than the
latter. 17-4 PH or S17400 precipitation– hardening alloy
type has lower nickel content but poor localised corrosion
resistance. 17-4 PH SS is usually used to manufacture wing
components of brackets or make mini-brackets due to its
higher hardness and strength.
Titanium brackets
Titanium as a metal has excellent biocompatibility and
increased corrosion-resistance. To overcome the release of
nickel from stainless steel brackets which may cause a nickel
allergy in some patients, titanium brackets were introduced
as nickel-free alternatives to SS in the mid-1990s. Con-
temporary titanium brackets are manufactured from alpha
titanium grade 2 and 4 or alpha-beta titanium (Ti-6Al-4V).
Grade 2 CP titanium is usually used to make the base com-
ponent of brackets due to its decreased strength, while the
wing component is made from much harder titanium alloy,
the alpha-beta titanium Ti-6Al -4V which is more wettable
than SS, so, it has a greater bond strength than SS. Also, ti-
tanium brackets are covered by a layer of titanium to reduce
friction.
Cobalt chromium
Cobalt-based wear-resistant alloys are used presently for
orthodontic brackets manufacturing. In cobalt-based, wear-
resistant alloys, CoCr brackets are made from ASTM F-75
CoCr where ASTM stands for American Society for Testing
and Materials. The amount of nickel in this alloy is kept low
and is up to 0.5 %. In theory, these brackets cause less nickel
sensitivity and less release of nickel. Also, these brackets are
harder but have less friction than SS brackets.
Types of the bracket base
These include:
• Perforated – obsolete
• Mesh- these are further subdivided into:
1. Foil mesh base
2. Gauze or woven mesh base
3. Mini-mesh base
4. Micro-mesh base
5. Optimesh base
6. Ormesh base
7. Laminated mesh base
8. Single mesh base
9. Double mesh base
10. Supermesh base
• Integral bases: Integral bases have furrows, pits and
undercut channels (Dynalok) for retention
• Photo-etched bases - microlock
• Laser structured bases
• Micro-etched bases
• Polymer-coated, e.g., Primekote (TP)
Bracket base surface area
An essential technical specification that affects the bond
strength of an orthodontic bracket is its base surface area.
Most orthodontists presently use twin brackets. The surface
area (Sorel et al., 2002, Haydar et al., 1999) of twin brackets
range from 12.5mm2
to 28.5 mm2
. The greater the retentive
bracket base area, the higher bond strength and vice versa
(Wang et al., 2004). But there are practical limitations of in-
creasing or decreasing the bracket base surface area though
the literature showed no direct relationship between bracket
base area and bond strength (Reynolds IR 1981). Clinically
acceptable bond strength (Reynolds, 1975) is around 5.9 to
7.8 Mpa but bond strength should not exceed than 13.5Mpa
(Retief, 1974) to avoid enamel damage.
Proffit (Proffit et al., 2018) proposed that the width of the
bracket should not be more than half of the width of the
tooth, while MacColl (MacColl et al., 1998) recommended
that bracket base surface area should be around 6.82 mm2
.
Usually, the manufacturers of orthodontic bracket keep
larger base area to give better bond strength and rotational
control.
Orthodontic brackets recycling
Although different commercial companies provide bracket
recycling services, brackets are routinely not recycled in the
UK (BOS 2011 Reuse of orthodontics devices, Coley-Smith
and Rock, 1997). Recycling has a negligible change in slot
size but decreases bond strength in the case of mesh type
brackets. However, in cases of recycling using chemical or
heating, the corrosion resistance of the brackets decreases.

Tooth number 1 2 3 4 5 6 7
TIP
MBT 4 8 8 0 0 5 5
UPPER
LOWER
Roth 5 9 11 0 0 0 0
Andrews 5 9 11 2 2 5 5
Andrews 2 2 5 2 2 2 2
Roth 0 0 6 0 0 -1 -1
MBT 0 0 3 2 2 2 2
TORQUE
UPPER
LOWER
MBT 17 10 -7 -7 -7 -14 -14
Roth 12 8 0 -7 -7 -14 -14
Andrews 7 3 -7 -7 -7 -9 -9
TEETH 1 2 3 4 5 6 7
Andrews -1 -1 -11 -17 -22 -30 -30
Roth -1 -1 -11 -17 -22 -30 -30
MBT -6 -6 -6 -12 -17 - 20 -10
Bracket configurations
Standard Edgewise and Straight wire
Standard edgewise brackets which were introduced by Angle
(Angle, 1928) are rarely used. Nowdays, the most common
appliance system used in the USA is a preadjusted edgewise
appliance (O’Connor, 1993). The philosophy of preadjusted
edgewise system based on Andrew six keys of occlusion
(Andrews, 1976).
Like conventional edgewise, the bracket slot height could be
0.022”, 0.018” or mixed system,. For example, torque control
with 0.018” labially and 022” buccally. The bracket slot depth
is usually 0.028” but it can be in 0.025” or 0.030”. Slot size
and shape vary among the manufacturer because of varia-
tions in the manufacturing processes (Brown et al., 2015).
In 0.018” x 0.028” brackets, the working archwire is 0.016” x
0.022” SS while in 0.022” slot brackets, the working archwire
is 0.019” x 0.025” SS. According to an RCTs (Yassir et al.,
2019a, Yassir et al., 2019b, El-Angbawi et al., 2019), there
is no difference in terms of the effectiveness between 018”
and 022”. Similar findings were made by a systematic review
(Vieira et al., 2018).
In preadjusted edgewise brackets, the molar tubes are usually
convertible and could be single, double, or triple tubes,
with/without HG tubes (Tidy DC & Coley-Smith A, Swartz,
1994).
Bracket prescriptions
In preadjusted edgewise brackets, three-dimensional tooth
movements are built in the brackets, which is called the pre-
scription of the brackets. The prescription of the preadjusted
edgewise brackets has effectively removed the three aspects
of wire bending:
• In - out bend which is also called 1st order bend.
• Tip bend which is also called 2nd order bend.
• Torque bend which is also called 3rd order bend.
A number of brackets prescriptions are available (Table 3)
such as Andrew’s (Andrews, 1976), Roth’s, Alexander and
MBT prescriptions (McLaughlin and Bennett, 1989)
Begg appliance
The Begg appliance was introduced by Dr. Begg and then
modified into ‘Tip-Edge’ appliance (Kesling, 1988). Treat-
ment using Begg appliance involves three stages:
• Stage I: Alignment of teeth, correction of incisor and
molar relationships, relief of crossbite and rotations.
• Stage II: Space closure and maintenance of stage I
corrections.

6
• Stage III: Correct inclinations of teeth.
For more details, please read the chapter on Begg
appliances.
Tip-Edge’ system
The Tip-Edge brackets were introduced by Peter Kesling
(Kesling, 1988) in late 1988. Tip-Edge brackets are a modi-
fication of edgewise brackets using the treatment mechanics
of light wire and differential anchorage of the Begg system.
The Tip-Edge bracket has a dynamic slot, opened and closed
slot. The open slot dimension is 0.028” x 0.028” while the
closed slot dimensions is 0.022” x 0.028”. A modification of
the Tip-Edge bracket was Tip Edge plus by Parkhouse (Park-
house, 2007) in 2007; it contains an auxiliary horizontal slot
beneath the main archwire slot. At the the final stages of the
treatment, round 0.14” superelastic NiTi wire is passed in
the auxiliary slot replacing the sidewinders of the original
Tip Edge brackets.
The tip edge and tip edge plus system allows low friction and
early space closure but they are highly reliant on patients’
compliance and are asscoiated with complex mechanics in
stage III. No significant difference was found between the
preadjusted edgewise and tip-edge appliances in a prospec-
tive study comparing canine retraction rates (Lotzof et al.,
1996), however, there was less anchorage loss in Tip-Edge
patients.
Self-ligating (SL) appliances
Self-ligating brackets have an in-built metal face, which can
be opened and closed. The Russell Lock edgewise attach-
ment described by Stolzenberg in 1935 is an early example
of self-ligating brackets, but they were prone to breakages
and inadvertent opening. The Russell bracket was active
in demand. New designs continue to appear, with at least
twenty-four new brackets since 2000.
Factors that have hindered the adoption of self-ligation
These include:
• Design and manufacture imperfection.
• An inherent conservatism amongst orthodontists
• Lack of evidence of what low friction, secure arch-
wire engagement and light forces can achieve
Commonly used SL system
These include:
1. Passive SLB brackets such as:
• Damon SL brackets
• Damon 2
• Damon MX brackets
• Damon Q brackets
• SmartClip bracket
2. Active SLB brackets such as:
• In-Ovation GAC
• SPEED bracket
• Activa
3. Aesthetic options in SLB such as:
• In-Ovation C
• Damon 3
• Damon Clear
4. Lingual SLB such as:
• Philippe brackets
• Adenta LT brackets
Claimed advantages of SLB
These include:
• Full archwire engagement.
• Less chair-side assistance is required (Turnbull and
Birnie, 2007).
• Less chair-side time is required (Chen et al., 2010).
• Reduced number of appointments (Eberting et al.,
2001).
• Short treatment span (4-6mths) (Harradine, 2001)
though there is no evidence regarding improved effi-
ciency, faster alignment, stable or superior aesthetic
results using Damon (Wright et al., 2011, Dehbi et
al., 2017).
• Minimal incisor proclination when compared to
conventional brackets (Chen et al., 2010).
• Better oral hygiene with minimal accumulation of
S. mutants when compared to conventional brackets
(Longoni et al., 2017, Huang et al., 2018).
• Decreased root resorption (Yi et al., 2016).
• Better torque expression when compared to conven-
tional brackets, however, this benefit was negated by
a Al-Thomali’s systematic review (Al-Thomali et al.,
2017).
• Reduced friction (Pizzoni et al., 1998, Thomas et al.,
1998). However, according to a systematic review
(Ehsani et al., 2009), there might be less friction with
self-ligating brackets on the round wire, but there is
no difference with rectangular wires where friction
has greater implications.
• Better canine retraction when compared to con-
ventional brackets, however, literature showed that

there is no difference between self-ligating brackets
and conventional brackets between canine retrac-
tion and loss of anteroposterior anchorage (Zhou et
al., 2015).
Disadvantages of SLB
These include:
• Requires expertise for better results.
• Clips may get fractured/opened between appoint-
ments.
• Not possible to apply partial ligation.
• Costly.
• No evidence of treatment efficacy compared to con-
ventional ligation (Dehbi et al., 2017).
Fully-customised brackets
Fully adjusted brakcets are specifically designed according to
the situation/patient’s malocclusion. Fully customised brack-
ets such as Incognito are mainly used for lingual orthodon-
tics and are bonded indirectly (Andreiko, 1994, Wiechmann
et al., 2003).
The advantage of a customised brackets system is minimal
chair-side time, good arch coordination and improved fit-
ting of the brackets. The main disadvantage of this system is
increased cost. Also, the patient has to wait for the brackets
to be manufactured, thus, increasing the overall treatment
time.
Aesthetic Brackets
Lingual brackets
Lingual brackets have a long development history, but they
were first reported in 1978 by Kinja Fujita (Fujita, 1978) in
Japan to avoid injury to lips and cheeks by labial brackets for
patients who practised martial arts. Later on, lingual brack-
ets were introduced in United States in1982 by Alexander
(Alexander et al., 1982). In the early 1990s, Craven Kurz
developed his lingual bracket series, the seventh generation.
As the lingual surface of the tooth has more variations in
anatomy, there has been increase in popularity of custom-
ised brackets to account for this variation. Customised lin-
gual brackets uses CAD/CAM technology for the accuracy
of customisation.
Lingual brackets can be either directly bonded, for example,
In-ovation L, (Singh and Cox, 2011, Auluck, 2013) or cus-
tom-made and indirectly bonded, for example, Incognito.
Plastic brackets
The first commercially available plastic brackets were intro-
duced in 1963 by Morton Cohen and Elliott Silverman (Sil-
verman et al., 1979). Plastic brackets are either translucent
or transparent to fulfill aesthetic demand during treatment
and to make the appliance less visible. Plastic brackets are
usually manufactured from plastic injection molding and are
a good alternative to metal brackets for patients with a nickel
allergy. Conventional plastic brackets were made of unfilled
polycarbonate. The drawbacks of plastic brackets
are:
• They undergo water absorption in the oral cavity.
Water absorption has plasticising effects on the brackets
with a resultant decrease in mechanical properties of the
brackets.
• Staining increased bacterial growth over the brack-
ets. A foul odour from the mouth are also reported with
unfilled polycarbonate plastic brackets.
• The unfilled polycarbonate plastic bracket has a
stiffness 60 times less than that of stainless-steel brackets.
This decreased strength is further aggravated by the plas-
ticising effect of water absorption. Applying torque using
rectangular wires engaged in plastic brackets is extremely
difficult if not impossible because deformation or creep of
the bracket slot.
• Wing’s fractures of plastic brackets are common
because of decreased strength and wear -resistance.
• Plastic brackets offer greater friction to wires on
sliding mechanics than SS brackets because of the rough sur-
faces of the bracket slot. Also, the bracket slot is softer than
SS wires, so there are greater ploughing effects on sliding
steel wires.
• Some conventional unfilled plastic brackets need an
application of a special primer for bonding. Plastic brackets
have been reported to have lower shear bond strength than
conventional brackets.
• Polycarbonate plastic brackets are produced by
bisphenol A and phosgene CoCl. There are biocompatibil-
ity issues with polycarbonate brackets due to bisphenol A
release.
To overcome the problems of conventional plastic brack-
ets, different materials were used to manufacture plastic
brackets; these materials include polyoxymethylene, filled
polycarbonate, polyurethane brackets, and hybrid polymers.
Ceramic brackets
Ceramic brackets were introduced in the early 1980s and
extensively marketed in the mid- 1980s as the “invisible
braces”. Ceramic is the third hardest material known and
is harder than stainless steel and enamel. Ceramics are a
broad class of inorganic materials that are neither metallic
nor polymer and includes glasses, clays, precious stones, and
metal oxides. As ceramic brackets are transparent or trans-
lucent, hence, they mask the appearance of fixed appliances.

8
Table 4: Comparison between Monocrystalline and Poly-
crystalline Bracket
Monocrystalline brackets Polycrystalline brackets
Transparent as they contain a single crystal of aluminum oxide. Decreased optical clarity due to the presence of the binder
during the manufacturing process. Also, multiple crystals in
a polycrystalline bracket mean increases in the number of
grain boundaries and decreases in optical clarity.
They resist staining They discolour over time if used with some specific diets.
They are expensive (Scott, 1988) because they require a delicate
process to shape a single crystal into a bracket by cutting tools.
They are inexpensive because the moulding process is sim-
ple, and large quantities of brackets can be manufactured.
They have high tensile strength up to 1800 MPa (Johnson et al.,
2005)
The tensile strength is 380 MP meaning multiple grain
boundaries and less resistance to crack propagation (Flores
et al., 1990, Viazis et al., 1990)
The fracture strength decreases with time (Flores et al., 1990). Bracket strength remains unchanged with time.
They have smoother surfaces than polycrystalline brackets but
have equivalent friction resistance (Cacciafesta et al., 2003)
They have a rough surface compared to monocrystalline
brackets.
The bonding strength of monocrystalline versus polycrystalline brackets are controversial in the literature (Viazis et al., 1990,
Klocke et al., 2003)
Advantages of ceramic brackets
These include:
• High bond strength.
• Superior aesthetic.
• High wear resistance.
• Good colour stability over the plastic brackets.
• Inert and can safely be bonded in patients with nick-
el and chromium allergies.
• Safely used in patients who require multiple MRI
images.
Disadvantages of ceramic brackets
These include:
• Cost.
• Due to increased hardness, there is difficulty in
debonding with high chances of enamel damage and
bracket fracture. Therefore, they are contraindicated
in patients with enamel cracks, restorations or de-
vitalised teeth, hypoplastic teeth and hypocalcified
teeth.
• Discolouration of ceramic brackets in cases with
longer treatment times.
• Being the third hardest material, ceramic is harder
than SS wires. So, they offer greater friction on slid-
ing mechanics. They also cause teeth abrasion when
they contact the opposing teeth.
• Ceramic brackets are radiolucent and so cannot be
detected by x-rays if accidentally aspired or swal-
lowed during debonding.
• Ceramic brackets are made bulkier to resist fracture.
Bulkier brackets are more conspicuous and may
cause soft tissue injury.
Types of ceramic brackets
These include:
• Multiple crystals or polycrystalline brackets.
• Single crystal or Monocrystalline brackets.
• Zirconia brackets.
• Metal reinforced polycrystalline brackets.
Polycrystalline brackets
These are tooth-coloured brackets, e.g., 3M Clarity. Poly-
crystalline brackets are made by ceramic injection moulding
so they can be produced in large quantities, hence, they are
inexpesive compared to other ceramic brackets. However,
polycrystalline brackets are opaque and suffer from structur-
al imperfections, high friction and low fracture toughness.
Monocrystalline brackets
These are transparent brackets, e.g., Inspire Ice. They are
machined by milling from synthetic sapphire and they are
heat-treated to relieve stress, followed by cooling and then
milling. Monocrystalline brackets are clear with fewer im-
perfections, impurities and low friction than polycrystalline
brackets, however, they are expensive with low toughness.
Problems with ceramic brackets and suggested solutions are

listed in table 5.
Table 4: Problems with ceramic brackets
Problems Solutions
Error in bracket placement • Visualise from different angles.
• Coloured adhesives.
• Using transfer gauge.
• Bracket markers, although it can make removing the excess bonding material
more difficult.
• Indirect bonding.
Ligation problems such as:
• Clear and tooth-coloured elastic ligatures tend to discolour.
• Metal ligatures are obvious under clear brackets.
• Ligature’s lockers can fracture the brackets.
• Using Polycrystalline brackets.
• Using Teflon coated ligatures or ‘white’ elastomeric modules.
• Using thin Quickligs must be fully tied in with the twisted tails tucked under
the archwires.
•Using Self-ligating ceramic brackets.
Bracket fracture due to:
• Fracture of tie-wings during ligation.
• Fracture of brackets on debonding (if inhaled, can be problematic
because these are not radio-opaque).
• Careful application of torquing force, e.g., use rectangular.
• Careful ligation using stress relaxing composite ligatures (McKamey and Kusy,
1999).
High friction
• There is increased frictional resistance to sliding mechanics with
ceramic brackets (Tidy, 1989), especially with rectangular NiTi arch-
wires (Frank and Nikolai, 1980).
• Hard ceramic abrades stainless steel wire.
• Using lower friction ceramics e.g., zirconium oxide.
• Using ceramic brackets with metal lined slots.
• Closing loops rather than sliding mechanics for space closure.
• Bypassing premolar teeth during space closure.
Enamel wear
• Ceramic is 7 times harder than enamel.
• Enamel wear/fracture is common with ceramic brackets.
• Increased risk of enamel fracture when debonding.
• It is better to use ceramic brackets in the upper arch only.
• Avoid using ceramic brackets in the lower arch for deep bite cases.
• Using polycarbonate bracket in case of deep overbite.
• Using bite plane to clear the intermaxillary contact
• Procline upper incisors before bonding the lower incisors.
• Using rubber ligatures over tie wing slots of ceramic brackets can prevent con-
tact with the opposing dentition.
• To reduce enamel fracture, avoid using ceramic brackets in periodontally
involved teeth, root treated teeth, large restorations, small teeth, cracked enamel,
and lower incisors with thin labial enamel.
Debonding of ceramic brackets
It is essential to wear safety glasses to protect eyes while debonding
ceramic brackets, especially when debonding mechanically (Bishara
and Trulove, 1990).
There are different methods of debonding ceramic brackets, including:
• Mechanical method: First, remove the composite around the brackets and then
use manufacturer recommended tools to remove the brackets (Stewart et al.,
2014).
• Chemical debonding: Use of peppermint oil or other chemical solvents (75%
ethanol, polyacrylic acid, acetone, acetic acid) that plasticises the composites
• Ultrasonic debonding
• Thermal debonding using hot instruments tips, electrothermal or laser
debonding radiation (Obata et al., 1999)

10
Zirconia brackets
Zirconia brackets are polycrystalline brackets with an
opaque or yellowish tinge. Zirconia brackets are aesthetically
poor but have better fracture resistance and their frictional
properties are similar to alumina brackets (Keith et al.,
1994).
Metal reinforced polycrystalline brackets (MRPB)
MRPB incorporate a metal slot to reduce friction, and weak-
ness is intentionally introduced in the base to allow easy
removal.
Retention of ceramic brackets
The ceramic bracket bases are available in four different
designs to aid retention of adhesive:
• Chemical retention
• Mechanical retention
• Micromechanical retention
• Combination of the above designs
Initially, Vinyl silane coupling was used to increase the bond
strength, but it is associated with increased chances of enam-
el fracture on debonding. Nowadays, primarily mechanical
base retention is used. Other modifications in bonding are
using a weakening bonding agent, metal mesh in the base,
and introducing pre-stressed areas.
Other aesthetic brackets including composite brackets
Composite brackets are made from thermoplastic polyure-
thane and are available with metal slot. Composite brackets
have less staining/discolouration than polyurethane and less
enamel wear than ceramic brackets.
The differences between monocrystalline and polycrystalline
brackets are provided in Table 4.
EXAM NIGHT REVIEW
It is difficult to summarise this chapter; however, below is
the most important evidence for the exam:
• According to an RCT (Yassir et al., 2019a, Yassir et
al., 2019b, El-Angbawi et al., 2019) there is no differ-
ence between 0.018” and .022”. A systematic review
made a similar finding (Vieira et al., 2018).
• According to a systematic review(Chen et al., 2010),
less chairside time is required with SLB. Also, there
is less incisors proclination with the use of SLB when
compared to conventional brackets.
• According to a systematic review (Dehbi et al.,
2017), there is no evidence regarding improved ef-
ficiency of SLB over conventional brackets.
• According to a systematic review (Longoni et al.,
2017), with a low level of evidence, self-ligating me-
tallic brackets accumulate less S. mutants than con-
ventional brackets, improving infection control.
• According to a systematic review(Yi et al., 2016)
there is no evidence for the claim that SLB causes
less root resorption.
• According to a systematic review (Al-Thomali et al.,
2017) there is better torque expression by SLB.
• According to a systematic review (Ehsani et al.,
2009), there might be less friction with self-ligating
brackets on a round wire, but there is no difference
on rectangular wires where friction matters most.
• According to a systematic review (Zhou et al., 2015),
there is no difference between self-ligating brackets
and conventional brackets between canine retrac-
tion and loss of anteroposterior anchorage(Huang et
al., 2018).

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2
1. Begg philosophy
2. Indication of Begg appliance
3. Advantages of Begg appliance
4. Disadvantages of Begg appliance
5. Features of Begg appliance
6. Begg appliance therapy’s stages and their objectives
In this chapter
Begg
orthodontic
mechanics
Written by: Mohammed Almuzian and Haris Khan

BEGG ORTHODONTIC MECHANICS
14
PaulRaymondBegg(1889-1983)isanAustralianorthodon-
tits who studied at Angle school in USA from March 1924
to November 1925. He was trained in using both Ribbon
archwire appliances and Edgewise archwire appliances. Begg
returned to Australia in 1927 and moved away from Angle’s
non-extraction philosophy.
In 1933, Begg modified Angle’s ribbon archwire appliances by
turning the slot of the bracket upside down.
Begg also replaced the heavy 0.010 x 0.020-inch rectangular
gold wire of ribbon arch with 0.016 inches round stainless-
steel wire. therefore his appliance is also called a light wire ap-
pliance. Begg published his appliance and mechanics in 1956
(Begg, 1956).
Begg philosophy
Begg’s light wire appliance used differential anchorage dur-
ing tooth movement. In Begg philosophy, tooth movement
is performed on light wires. Therefore, the appliance had
poor control of root position which require different auxil-
iary springs later in the treatment to correct the root position.
Begg philosophy was based on two points:
1. Tooth extraction: Begg looked at Aborigines’ dentition
and noticed an excessive amount attrition and abrasion had
occurred due to a course diet. He noticed wear occurring in
two planes:
• Occlusal/incisal wear: Wear to the cusps reduces
interdigitation. Consequently, the mandible comes
forward into an ‘edge to edge’ type of occlusion.
• Interproximal wear: The contact points become
broad over time with loss of interproximal enamel
from distal of the second molar to second molar,
this is equivalent to the loss of one premolar in each
quadrant.
2. Differential force technique: The differential force tech-
nique is the key aspect of the Begg appliance approach The
differential force technique is based on the theory that force
required to tip a tooth is less than the force required to bodily
move the tooth. With differential force technique, teeth are
moved in a two-stage process, tipping followed by uprighting
in the final position. .
Indication of Begg appliance
These include:
• Compliant patients who require long appointment
intervals.
• There are no facial concerns regarding orthodontic
iatrogenic retrusion of the facial profile or ‘dishing
in.’
• Class II division I cases with an increased overbite,
full unit II molars, and crowding needing four ex-
tractions is the most common.
• High anchorage demand cases.
• Bimaxillary protrusion (Lew, 1989)
Advantages of Begg appliance
These include:
• Permits all tooth movements to be carried out rap-
idly and over great distances without re-activation
(Begg and Kesling, 1977).
• There is less demand upon anchorage because of the
lack of friction effects with free tipping, light forces,
and differential force. Hence, the extraoral anchor-
age is usually not needed (Begg and Kesling, 1977).
• Minimal post-treatment relapse (Begg and Kesling,
1977).
Disadvantages of Begg appliance
These include:
• Extraction-based technique.
• Requires patient compliance, requires the continu-
ous wear of elastics.
• Oral hygiene problems because of the loops on the
wire.
• Dishing of the face during the first stage of treat-
ment.
• The appliance becomes complicated to manage in
later stages due to the need of accessories.
• Potential for increased root resorption and peri-
odontal problems, due to unlimited tipping and
counter-tipping, especially in mature patients.
• Backward rotation of the mandible due to molar
extrusion can have a detrimental effect on the face,
especially in open-bite cases.
• Bite opening, anchorage loss (especially in the max-
illa), and insufficient maxillary incisor torque were
found in the Begg appliance compared to the edge-
wise appliance (Barton, 1973). However, a systemat-
ic review (Mousoulea et al., 2017) found low-quality
evidence that Begg and modified Begg appliances
show a statistically significant worsening in occlusal
outcomes when assessed with the Peer Assessment
Review (PAR) scores compared to a preadjusted ap-
pliance with Roth prescription.
Features of Begg appliance
These include:
• Gingival opening of the bracket to prevent the an-

BEGG ORTHODONTIC MECHANICS 15
chor bends from being bitten off. Hence, wire is al-
ways placed in gingivally.
• The bracket has minimal mesiodistal width with
single point contact on incisors, canines, and pre-
molars, allowing tipping and rotation. Therefore,
less force is required.
• Molar tubes have a round buccal tube with a hook,
which achieves two-point contacts; this imparts
bodily movement.
• Early Class II elastics.
• Accessory springs and archwire modifications are
used at later stages for apical and rotational tooth
movements.
Begg appliance therapy’s stages and their objectives
Stage I
A. Intra-arch tooth alignment objectives including:
• Relief of crowding
• Overcorrect rotations of all teeth except anchor mo-
lars
• Align impacted and unerupted teeth
• Tooth levelling
• Closure of anterior spacing
B. Transverse correction objectives including:
• Coordinate upper and lower dental arches, achieve
symmetry
• Correct cross-bites of posterior teeth
C. Vertical correction objectives including:
• Overcorrection of overbite to edge to edge
D. AP correction objectives including:
• Overcorrection of overjet to edge to edge
Stage II which aim to:
• Maintain stage I objectives
• Correct centrelines
• Premolars alignment
• Close remaining extraction spaces
Stage III which aim to:
• Maintain space closure
• Correct mesiodistal angulation (tip) using upright-
ing springs
• Correct labio-lingual inclination (torque) using
torquing springs.
• Finishing and retention
References:
EXAM NIGHT REVIEW
Begg published his appliance and mechanics in 1956 (Begg,
1956). Begg philosophy was based on tooth extraction and
differential force technique
Indication of Begg appliance
• Compliant patients
• No facial concerns
• Class II division I with an increased overbite
• High anchorage demand cases
• Bimaxillary protrusion
Advantages
• Movements to be carried out rapidly
• Less demand upon the anchorage
• Minimal post-treatment relapse
Disadvantages
• Extraction based technique
• Requires patient compliance
• Oral hygiene problems
• Dishing of the face
• Potential for increased root resorption and peri-
odontal problems
• Backward rotation of the mandible
• Bite opening, anchorage loss

BEGG ORTHODONTIC MECHANICS
16
Barton, J. J. 1973. A cephalometric comparison of cases treated
with edgewise and begg techniques. Angle Orthod, 43, 119-26.
Begg, P. R. 1956. Differential force in orthodontic treatment. Am J
Orthod 42, 481-510.
Begg, P. R. & Kesling, P. C. 1977. Begg orthodontic theory and
technique, WB Saunders Company.
Lew, K. 1989. Profile changes following orthodontic treatment of
bimaxillary protrusion in adults with the begg appliance. Eur J
Orthod, 11, 375-81.
Mousoulea, S., Papageorgiou, S. N. & Eliades, T. 2017. Treatment
effects of various prescriptions and techniques for fixed orthodon-
tic appliances : A systematic review. J Orofac Orthop, 78, 403-414.

3
1. Advantages of removable appliances (RAs)
2. Disadvantages of RAs
3. Indications of RAs
4. Components of removable appliances
5. Active components of RAs
6. Retentive components of RA
7. Anchorage component of RA
8. Base Plate
9. Mode of action of RAs
10. Checklist for RAs
In this chapter
REMOVABLE
ORTHODONTIC
APPLIANCES

REMOVABLE ORTHODNTIC APPLIANCES
18
Removable appliances (RAs) are orthodontic devices that
can be removed and inserted by the patient. The advantages
and disadvantages of RAs are listed in table 1.
Indications of RAs (Reay and Stephens, 1993)
These include:
1. As an interceptive active appliance for the management of:
• Anterior crossbites correction.
• Posterior crossbites correction.
2. As an interceptive passive appliance for the management
of a habit.
3. As a space maintenance appliance for the management of:
• Early loss of primary teeth.
• The traumatic loss of permanent anterior teeth.
• Permanent tooth extraction awaiting eruption of
impacted teeth.
4. Active orthodontic appliance for:
• Treating retroclined upper incisors in Class 2 Divi-
sion 2 cases (e.g., ELSAA type appliance)
• Treating narrow upper arch
• Maintain the result of the functional appliance, e.g, a
removable appliance with an anterior inclined plane.
• Headgear combination therapy to aid en masse re-
traction, molar distalisation or posterior teeth intru-
sion.
5. As an adjunct appliance to fixed appliance therapy for:
Table 1: The advantages and disadvantages of RAs
• Cost-effective.
• The removable nature of the appliance makes it possible for
the patient to maintain good oral hygiene during treatment.
• Patients can remove damaged appliances.
• Laboratory fabricated rather than directly in the ‘patient’s
mouth, therefore, less chair-side time.
• Allow growth guidance treatment to be carried out more
readily than with fixed appliances
• Less iatrogenic effect than fixed appliances such as decalcifi-
cation, caries under molar bands, and gingivitis.
• They can be used during the mixed dentition for various
interceptive treatments.
• Not effective with an uncooperative pa-
tient.
• Efficient tooth movement in three dimen-
sions is not possible. Traditional RAs are only
capable of tipping movements
• Only certain types of malocclusions can be
corrected.
• They may hinder speech and eating.
• Difficult to tolerate lower appliances.
• Appliances may be lost or broken.
• Residual monomer (greater in self-cure ap-
pliances) may cause allergy and/or irritation.
• Overbite correction
• Open bite correction
• Disengaging the occlusion and removing occlusal
interferences to enhance tooth movement, by incor-
porating bite planes.
• Extruding teeth, such as impacted palatal canines.
• Provide lower posterior attachments for Class 2 in-
ter-arch elastics/traction in Class 2 malocclusions.
6. As a retainer appliance such as:
• U loop labial bow retainer (Hawley).
• Begg retainer.
• Vacuum-formed retainers.
Wires used to construct RAs
The composition of austenitic stainless-steel wires used to
construct RAs is iron 73%, chromium 18%, nickel 8%. This
stainless-steel wire is 18/8 stainless steel (18 refers to the per-
centage of chromium included while 8 refers to the level of
nickel incorporated). For the construction of spring of a re-
movable appliance, hard stainless steel is usually used, but it is
possible to use medium-hard in some situations.
Elgiloy can also be used to construct RAs sporing. Elgiloy
wire consists of iron 14%, chromium 20%, cobalt 40%, nickel
16%, molybdenum 7%, manganese 1.5%. Elgiloy wire is avail-
able in four grades red (resilient), green (semi resilient), yel-
low (ductile) and blue (soft). Elgiloy is generally used in its
soft blue form to construct Southend clasps or other clasp
components for removable appliances. Heat-treating the wire
increases its strength significantly.

REMOVEABLE ORTHODONTIC APPLIANCES 19
Components of RAs
Active components
Active components deliver forces to achieve orthodontic
tooth movement, component types are::
1. Bows are active components that are mainly used for inci-
sor retraction. Types of bows include:
• Short and long labial bows (0.7mm SS). Because of
the high force levels, a labial bow with U loops (0.7
mm SS) are used for minor incisor retraction.
• Labial bow with reverse loops mesial to second pre-
molars (0.8 mm SS).
• Labial bow with large C loops (0.7mm SS)
• Split labial bow (0.7mm SS).
• Reverse labial bow (0.8mm SS).
• High labial bow with apron springs in which the
base arch is made from 1 mm SS, and the apron
spring is made from 0.35-0.4 mm SS).
• Mills retractor.
• Robert’s retractor (0.5 mm SS supported with
0.7mm SS sleeve).
• Self-straightening bows (0.4 mm SS).
2. Bite planes are made of acrylic and are an active compo-
nent. Bite planes can be used for:
• Intrusion of teeth.
• Extrusion of teeth: Teeth not in contact with the bite
plane extrude passively /over-erupt.
• Open the bite in cases of premature contacts, cross-
bite or used to advance or setback the mandible e.g.
Twin block and reverse Twin block.
3. Springs are an active component of RAs used to deliver
tooth movements. Springs can be classified into springs with
helix, spring without helix, spring with loops and self-sup-
ported springs. The ideal properties of springs are that they
should be easy to fabricate, adjustable, easy to clean, engage
with tooth surface without discomfort and extended range of
activation.
Springs are mainly cantilevers in nature, i.e., supported at one
end (also called the tag) and free at the other end to deliver
the force. These include:
• Z spring (0.5mm SS) is mainly used anteriorly to
procline / rotate teeth. It requires good anterior re-
tention and is activated by 3mm through the open-
ing of helixes, at 45 degrees to the base plate.
• T spring (0.6mm SS), mainly used posteriorly to tip
teeth buccally. Capping of the springs is essential for
crossbite correction. A T-spring is activated by 2mm
reduction/compression of T bend.
• Palatal spring (0.5mm SS for central to 2nd premo-
lar, 0.6mm SS for molars) can be used both anterior-
ly and posteriorly to move teeth mesial or distal, and
it is activated by 3mm through opening or closing of
the helix.
• Canine retractor (0.5 / 0.6mm SS) are a specific type
of palatal springs that can also be placed buccally. It
moves canines in a distal direction. Examples are U-
loop canine retractor, helical canine retractor, buccal
and palatal canine retractor.
• Buccal spring / reverse buccal spring (0.7mm SS, if
sleeved 0.5mm SS) are used to move teeth distally.
1mm of activation is required, and this is most read-
ily done by cutting off 1 mm of wire from the free
end and re-forming it to engage the mesial surface of
the tooth. Alternatively, it can be activated by open-
ing the loop by 1 mm.
• Robert’s retractor (0.5 mm SS with SS sleeving) are
used to retract anterior teeth. It consists of a labial
bow connected to two buccal retractors, and it is ac-
tivated by closing the helix by 3mm.
• Coffin spring (1.25mm SS) is used for the maxillary
arch expansion and is activated by pulling the two
halves apart.
The force applied by the springs should be perpendicular to
the long axis of the tooth, and should be as close as possible
to the centre of resistance. The force delivered by the spring
is presented by the following formula: Force ᾳ dr4
/l3
. This
means the force will be lighter with a greater length of wire
in the spring, the reduced radius of the wire and reduced de-
flection. It is recommended that when the wire is activated
from its passive position, the direction of activation should
be in the same direction as planned tooth movement. This is
due to increased steel hardening (Bauschinger effect) which
might fracture while un-winding; hence is why reverse loops
are preferred. Wire flexibility is essential to deliver the de-
sired force for tipping movement. Increasing flexibility is rec-
ommended by increasing the length through incorporating
coils or reducing the diameter, however, this might affect the
spring rigidity. This can be resolved, using a guided wire or
reinforced wire with a tubing sheath.
4. Screw, mostly, a jackscrew is used with RAs, but other
screws can be utilised. Screws can be used for the following
purpose:
• Arch expansion (screws are expanded on slow ex-
pansion protocols, one turn on alternative days or
two turns a week, equating to 0.5-1mm/week).
• Arch contraction.

20
• Space opening.
• Space closing.
• Tooth movement buccally or labially.
Retentive components of RAs
Retentive components help in keeping the appliance in place
and resist displacement. Incorporating specific wire / plas-
tic parts that engage undercuts on the teeth, such as clasps,
which provide retention.
The ideal properties of retentive clasps are:
• Easy to fabricate and offer adequate retention.
• They should not apply any active force that would
cause undesired tooth movement of the anchorage
teeth.
• They should not impinge on the soft tissues/or in-
terfere with normal occlusion.
The types of retentive clasps include:
• Adam’s clasps which are commonly made from 0.7
mm wire for molar teeth and in the case of premolar
teeth a 0.6 mm wire is used. The bridge of an Ad-
ams’ clasp provides a site where the patient can ap-
ply pressure with their fingertips during the removal
and insertion of the RA. Moreover, auxiliary springs,
extraoral traction tubes and hooks can be soldered
to the bridge of the clasp.
• Southend clasps are made from 0.7mm or 0.8-mm
SS wire or Elgiloy wire. These clasps are activated by
bending the U-loop towards the baseplate, which
moves the clasp back into the labial undercut of the
tooth.
• C-clasps is also called a recurved clasp and it is fab-
ricated from 0.7 mm SS wire.
• Ball-ended clasps are made from 0.7 mm wire.
• Plint clasps around molar bands is made from 0.7-
mm SS and engages the undercuts on a maxillary
molar band.
• Acrylate and fitted labial bow (0.7 mm SS).
Anchorage component of RAs
Anchorage should be considered in all three planes of
space. The greater the number of teeth incorporated into
the appliance, the greater the anchorage value of the ap-
pliance. Teeth with larger root surface areas incorporated
within the appliance will also provide more anchorage.
The use of light forces reduces the burden on the anchor-
age components. Intermaxillary anchorage used with
elastics running from the upper to the lower arch may be
used to optimise anchorage. This does, however, increase
the demand on the retentive part of the appliance, and an
operator needs to be confident in the retentive compo-
nent of their appliance.
Baseplate
It is constructed from self-polymerising or heat polymerising
polymethyl methacrylate. The base plate has four functions:
• It acts as a connector of the appliance parts.
• It contributes to anchorage through contact with the
palatal vault and teeth not being moved.
• It may be built up into bite planes to disengage the
occlusion or produce overbite reduction (anterior or
posterior bite plane).
• It provides housing and protection of the URA com-
ponents.
Material of the base plate is contracted via a polymerisation
process of the following:
• Powder or polymer, known as polymethyl methac-
rylate + peroxide initiator + pigment
• Liquid monomer methacrylate + stabiliser hydro-
quinone to prevent polymerisation on storage and a
cross-linking agent.
The polymerising process:
• Heat cured: It has the advantage of not releasing
polymerised monomer, which has been reported to
cause skin and mucosal reactions for technicians,
dentists, and patients.
• Self-cured, cold-cured, auto-polymerizing, or
chemically-activated acrylic is similar to the heat
cure material, except the liquid contains an activa-
tor, such as dimethyl toluidine.
• Light cured
• Dual cured
Designing RAs
Appliance design in conjunction with good diagnosis is the
key to successfully treating an orthodontic problem. No mat-
ter how well made, an inappropriately designed appliance is
unlikely to achieve optimum tooth movement and thus the
desired result. The stages of appliance design are as follows:
• Select the active components required to achieve the
type and direction of tooth movements needed.
• Select the retentive components that enable the ap-
pliance to remain in its desired position and not to
be displaced when the active components are acti-
vated.
• The base plate holding active and retentive compo-

nents together must be designed to have all these
components together. Thought must be given to pa-
tient comfort.
• An estimate of additional anchorage requirements
are considered at this stage, specifically if the base
plate along with the retentive clasps is sufficient
for the type of tooth movements that is desired, or
whether additional anchorage requirements are
indicated, such as the addition of headgear (distal
movement, protraction) or inter-maxillary elastics.
Mode of action of RAs
RAs can carry out limited tooth movement predictably (Ward
and Read, 2004). The predictable movements are listed below:
• Tipping in labio-lingual or mesiodistal directions.
• Reduction of deep overbites in growing individuals
• Space maintenance
More complex movements involving bodily or root changes
are unpredictable due to challenges in creating a force couple.
Aligners are theoretically able to achieve a force couple; how-
ever, the predictability of root movement with aligners is low
(Dai et al., 2019)
Tipping movement (Christiansen and Burstone, 1969): A
force applied as a single point on the crown will tip the tooth
about a fulcrum. Tipping takes place about a fulcrum within
the apical third of the root, the centre of rotation is usually
about 40% of the length of the root from the apex. This means
that while the crown moves in one direction, the apex moves
in the opposite direction (also termed uncontrolled tipping).
The exact level of the fulcrum depends on a variety of factors,
that are not under the orthodontist’s control; these include
root shape, periodontal support and the distribution of fibre
bundles within the periodontal ligament.
Intrusion movement: When a bite plane is incorporated
into an appliance, an intrusive force is applied to the teeth
which contact it. The amount of actual intrusion is small, and
overbite reduction with removable appliances is primarily the
result of the passive eruption of the dentoalveolar segments
not occluding on the bite plane, typically the posterior teeth.
Incisors may tip labially if they do not occlude perpendicu-
lar to the anterior bite plane. Intrusion of teeth may also be
produced unintentionally by the incorrect application of a
spring. For example, when a spring retracts, the canine is ap-
plied to the cuspal incline, the tooth will be intruded as well as
retracted. This most often happens when attempts are made
to retract a partially erupted canine. For the same reason, it
is preferable to avoid moving a tooth until it is fully erupts.
Rotation movement: Rotations are challenging to correct
with RAs becasue of the requirement to generate a force cou-
ple. Some rotations can be rectified by applying simultane-
ous buccal and lingual forces. For example, a rotated upper
central incisor, it may be possible to correct a rotation with a
couple between a labial bow and a palatal spring at the base-
plate, but this requires careful management.
Checklist while fitting a new RA
It is important to undertake a thorough check during the first
and recall visits. The tables below is a checklist for this pur-
pose (Table 2 and 3).
Table 2: Checklist while fitting a new RA
Item Yes/ No
Is it the correct
appliance for the
patient?
Is it the correct
design?
Check for any
sharp areas
Show the ap-
pliance to the
patient
Insert appliance
into the mouth
and assess fit of
the appliance
Adjust the clasps
to generate suf-
ficient retention
Activate and
trim acrylic to
enable the ap-
propriate tooth
movements
Final try in
Inform the pa-
tient of the time
appliance is to
be worn per day
Instruct the pa-
tient on how to
take care of his
appliance, and
provide infor-
mation leaflets
on managing
removable appli-
ances
Arrange a recall
visit

22
Disadvantages of removable orthodontic appliances:
• Not effective with uncooperative patients.
• Mainly tipping movements.
• Limited control of tooth movement.
• Only certain types of malocclusions can be correct-
ed.
• Speech and eating affected.
• Inefficient for multiple tooth movement.
• Lower appliances are poorly tolerated.
• The residual monomer is allergenic.
Indications of removable orthodontic appliance: (Reay and
Stephens, 1993)
A. Interceptive treatment
1. Active
• Correction of anterior crossbites
• Correction of posterior crossbites
2. Passive
• Habit-breaker
3. Space maintenance
• Early loss of primary teeth
• Traumatic loss of incisors.
• After permanent tooth extraction to allow impacted
teeth to eruption
Table 2: Checklist on recall visits
Inquire about any problems Yes/No
Inquire what wear pattern
Assess speech, the quality of speech can be gauged as this indicates if the patient has been wearing
the appliance
Check appliances inside the mouth prior to removal. This allows oral hygiene to be assessed, and
any trauma spots can be identified
Ask the patient to insert/remove the appliance; ease of performing these tasks indicates good
compliance
Recognising unwanted tooth movements at an early stage and undertaking remedial action at this
stage is of the utmost importance
Check springs are correctly positioned and fit of the appliance. If the fit is poor and springs are
displaced, it indicates the patient has been flicking the appliance in and out with their tongue and
has made appliance loose. This can produce fractures of the wire components during treatment
Measure the overjet reduction/relevant tooth movements and note in patients file
Check molar relationships for anchorage loss
The appliance must be adjusted with care and good records need to be kept
Oral hygiene should be carefully monitored and reinforced
EXAM NIGHT REVIEW
Definition:
RA→ can be taken out of the mouth by the patient.
Classification of RA
Active Appliances
Produce tooth movement/growth modification, e.g., Func-
tional appliance, a removable appliance with z springs in
Class II div 2 corrections.
Passive appliances
These are RAs where no active tooth movement is present.
These include retainers space maintainers.
Advantages of removable orthodontic appliances:
• Removable
• Laboratory fabricated, less chair-side time.
• Growth guidance possible
• Good oral hygiene during treatment.
• Less orthodontic risks such as decalcification loss of
attachment.
• Cost-effective.
• It can be used during mixed dentition
• Interceptive treatment possible
• Maintaining space.

B. Removable appliances as an adjunct to fixed or func-
tional appliance therapy.
• Pre-functional appliances to procline incisors in a
Class II Division 2 case and expand the upper arch.
• Enabling distal movement by adding headgear ther-
apy.
• Overbite correction.
• Disengage occlusion with bite planes
C. Removable orthodontic appliance as a retainer:
• ‘’’U’ loop labial bow retainer [Hawley]
• Begg retainer
• Vacuum-formed retainers.
• Material
• Baseplate: Acrylic
• Plastic type appliances: Polypropylene / polyvinyl-
chloride
• Wires: Stainless steel, Elgiloy
• Elastics
Components of removable appliances
Components of RA include
• Active components
• Retentive components
• Anchorage components
• Baseplate
Type of springs in RA
Mostly cantilever springs are used in RA. These include:
• Z spring (0.5mm SS), activated by 3mm opening of
helix
• T spring (0.6mm SS), posterior capping required,
activation 3mm
• Palatal springs (0.5mm / 0.6mm SS anterior / mo-
lars) activated by 3mm through opening or closing
of the helix
• Canine retractor (0.5 / 0.6mm SS)
• Buccal springs (0.7mm SS, if sleeved 0.5mm SS)
• Robert’s retractor (0.5 mm SS with sleeving). Activa-
tion is 3mm through closing the helix.
• Coffin spring (1.25mm SS), Activate by pulling 2
halves apart.
Retentive components of RA (Seel, 1967)
• Adam’s clasp: 0.7 mm SS for molar teeth, 0.5 mm for
premolar teeth.
• Southend clasp: 0.7- or 0.8 mm elgiloy.
• C-clasp: 0.7 mm SS
• Adam’s crib: 0.7 SS / 0.6mm SS permanent / primary
teeth.
• Ball ended clasps: 0.7 mm SS.
• Splint clasp: 0.7 mm SS wire.
Anchorage component of RA
• Teeth
• The base plate
• Extraoral forces

24
References
Christiansen, R. L. & Burstone, C. J. 1969. Centers of rotation
within the periodontal space. Am J Orthod, 55, 353-69.
Dai, F. F., Xu, T. M. & Shu, G. 2019. Comparison of achieved and
predicted tooth movement of maxillary first molars and central
incisors: First premolar extraction treatment with invisalign. Angle
Orthod, 89, 679-687.
Reay, W. J. & Stephens, C. D. 1993. Indications for the use of fixed
and removable orthodontic appliances. Dent Update, 20, 25-6,
28-30, 32.
Seel, D. 1967. A rationalization of some orthodontic clasping prob-
lems. Dent Pract Dent Rec, 17, 188-95.
Ward, S. & Read, M. J. 2004. The contemporary use of removable
orthodontic appliances. Dent Update, 31, 215-8.

4
1. Indication of clear aligner therapy (CAT)
2. Contraindication of CAT
3. Advantages of CAT
4. Disadvantages of CAT
5. Evidence about CAT
6. EXAM NIGHT REVIEW
In this chapter
Overview Of
Clear Aligner
Appliances

clear alligner appliances
26
Sheridan initially described the idea of clear aligner therapy
(CAT) (Sheridan, 1994) by introducing the first vacuum-
formed Essix polyurethane plastic for minor tooth move-
ment. CAT is an orthodontic technique that uses a succes-
sion of clear aligners to position the teeth. The system uses
CAD/CAM stereolithographic (STL) technology to predict
treatment outcomes and create custom aligners from a single
model.
Aligners are used 24/7 (apart from eating,drinking and
brushing) and replaced every 1-2 weeks to move the teeth by
0.2-0.25mm on each aligner. Aligners are provided by many
suppliers and can also be produced locally (in-house align-
ers or IHA). The Invisalign system is one of the popular CAT
systems introduced by Align Technology (Santa Clara, Calif)
in 1998.
The conventional fixed appliance system can explain the
components of CAT. For example, aligners’ attachments, akin
to an orthodontic auxiliaries, permit the force delivery from
the aligner. At the same time, the plastic part (aligner) rep-
resents a wire. So, the aligner’s shape elicits a pushing force
on the teeth. These pushing forces come from the bending/
deformation of the plastic, followed by the aligner returning
to its original shape (shape memory).
General indications of CAT
These include:
• Mild to moderate crowding (1-5 mm).
• Spacing (1-5 mm).
• A mild to moderate degree of anterior open bite
where the overbite is improved by extrusion of the
incisors.
• Mild degree of deep overbite, decreased by intrusion
and proclination of the incisors.
• Narrow arches that can be expanded with tipping
teeth.
General limitations of CAT
These include:
• Crowding over 5 mm.
• Spacing over 5 mm.
• Anterior-posterior discrepancies of more than 3
mm.
• Significant open bite correction.
• Severely rotated teeth more than 20 degrees.
• Severely tipped teeth, more than 45 degrees.
• Teeth with short clinical crowns.
Claimed advantages of CAT
These include:
1. Patients preference due to aesthetic appliance.
2. Less iatrogenic effects: According to a systematic review
(Elhaddaoui et al., 2017), clear aligner therapy delivers
less chance of root resorption than a fixed appliance in
non-extraction cases. Similar results were found by other
systematic reviews and meta-analyses (Fang et al., 2019,
Aldeeri et al., 2018). However, a systematic review by
Gandhi (Gandhi et al., 2021) found a significant differ-
ence in root resorption between the clear aligner and
fixed appliances only on right maxillary lateral incisors
with fixed appliances causing more resorption. Accord-
ing to a systematic review (Cardoso et al., 2020), orth-
odontic patients treated with Invisalign appear to feel
lower pain levels than those treated with fixed appliances
during the first few days of treatment.
3. Less detrimental effects of the periodontal tissue (Ros-
sini, et al. 2015a, Karkhanechi et al., 2013) mainly due
to improved oral hygiene, minimal uncontrolled tipping
teeth, light force system and minimal planned movement
(linear and angular movement in the range of 0.12mm
and 1 degree respectively per aligner). However, it was
found that the concentration of biological markers were
similar for aligners and fixed appliances (Castroflorio, et
al. 2017).
4. Improved efficiency due to longer visit intervals, up to 12
weeks. A systematic review (Zheng et al., 2017)
found that the current evidence on aligners only sup-
ports shortened chair time and treatment duration in
mild-to-moderate cases compared to conventional fixed
appliances. According to a systemic review (Rossini
et al., 2015b), it was concluded that there is low-quality
evidence that aligners treatment is associated with im-
proved periodontal health indices. Similar results were
put forward by another meta-analysis(Jiang et al., 2018).
It was suggested that aligners could be used in orthodon-
tic patients who have a high risk of developing gingivitis.
5. Improving technology development.
6. An acceptable range of tooth movement including:
• Anterior alignment and buccolingual changes are
almost comparable to fixed for anterior (Robertson,
et al. 2020)
• Tipping movement are 77% as accurate as fixed
appliance therapy (Weir 2017), while bodily move-
ment is 36% as accurate as fixed appliance therapy
(Zhou and Guo 2020)
• Obtaining 2.6mm of molar distalisation without the
use of skeletal anchorage (Simon, et al. 2014)

clear alligner appliances 27
• Achieving expansion of 2mm at the canine region.
• Vertical control in high angle and anterior open bite
cases, achieving an average of 3.27mm of overbite
due to a combination of maxillary and mandibular
incisor extrusion and maxillary and mandibular
molar intrusion (Harris, et al. 2020a)
Disadvantages of CAT
These include:
1. Aesthetics of attachments: An eye-tracking technique
compared photos of patients with attachments in different
locations in the mouth, this study showed that laypeople no-
ticed attachments and preferred ceramic brackets over align-
ers with anterior attachments (Thai, et al. 2020).
2. Patient satisfaction with the outcome is below that
achieved with the fixed appliance (Thai, et al. 2020). The
mean accuracy of Invisalign for all tooth movements was es-
timated at 41% in a clinical study (Kravitz et al., 2009). Djeu
et al. (Djeu et al., 2005) made a retrospective comparison of
outcomes of non-extraction Invisalign and fixed appliance
treatments, using the ABO objective grading system (Thomas
Set al 1998), and found a significant difference in the pass rate
of Invisalign compared to Tip-Edge treatment (20.8%, 47.9%,
respectively) and the time for Invisalign at 1.4 years com-
pared to 1.7 years for Tip-Edge treatment. So, Invisalign is
shorter in the duration of treatment but with poor outcomes.
It is shorter in time because it moves the teeth without round-
tripping to the defined final position. Lagravere’s (Lagravère
and Flores-Mir, 2005) systematic review found insufficient
evidence for the treatment effects of Invisalign treatment. The
study concluded that clinicians must rely on their Invisalign
clinical experience when using Invisalign appliances.
3. Except for minor horizontal movements (Robertson, et
al. 2020), almost all movements have poor accuracy and pre-
dictability with CTA, for instance:
• Deep bite reduction is unpredictable, and a maxi-
mum of 1.6mm correction can be achieved (Khos-
ravi, et al. 2017) with around 50% of accuracy (Al-
Balaa, et al. 2021).
• Rotational and vertical movements have poor pre-
dictability (Charalampakis, et al. 2018) with 40% ac-
curacy for the derotation (Simonds and Brock 2014).
• More than 2mm of space closure is difficult to
achieve with CAT (Papadimitriou, 2018)
• The average predictable distalisation is 1.5-2.6mm
• Expansion is achieved mainly via tipping (Houle,
2017; Zhou, 2020)
• 80% of clear aligner cases that were submitted to the
American Board of Orthodontics failed to pass the
criteria compared to 50% failure with fixed appli-
ance (Djeu, 2005).
• According to a systematic review (Rossini et al.,
2015a), clear aligner therapy effectively achieve the
following: level align, anterior intrusion, contro
posterior buccolingual inclination and upper molar
bodily movements of about 1.5 mm. Aligners are
ineffective in anterior extrusion, correction of tooth
rotation, notably round teeth, and controlling ante-
rior buccolingual inclination. The present evidence
was of low quality.
4. Additional refinement is likely in most cases as 50% of
the overall movements is achieved with the first set of align-
ers, with the first refinement accuracy increases to 75%
(Haouili, 2020). Many orthodontists, however, report that
70-80% of patients require case refinement and /or detail-
ing with fixed appliances. Align Technology suggests that
20-30% of patients may require mid-course fixed appliance
orthodontic appliance correction to achieve the predicted
treatment outcome. For adult patients, a systematic review
(Papageorgiou et al., 2020) found that aligners are associ-
ated with worse treatment outcomes than fixed appliances.
EXAM NIGHT REVIEW
History
Sheridan initially described CAT in 1980 and 1990 (Sheri-
dan, 1994)
General indications of CAT
• Mild to moderate crowding
• Mild spacing
• Mild overbite problems
• Narrow arches that can be expanded without tip-
ping the teeth too much.
General limitations of CAT
• Crowding over 5 mm.
• Spacing over 5 mm.
• Anterior-posterior discrepancies of more than 2
mm.
• Significant open bite correction.
• Severely rotated teeth more than 20 degrees.
• Severely tipped teeth, more than 45 degrees.
• Teeth with short clinical crowns.
Claimed advantages of CAT
• Ideal aesthetics
• Less pain, decalcification and OIRR compared to
conventional fixed appliance therapies.

clear alligner appliances
28
References
Aldeeri, A., Alhammad, L., Alduham, A., Ghassan, W., Shafshak, S.
& Fatani, E. 2018. Association of Orthodontic Clear Aligners with
Root Resorption Using Three-dimension Measurements: A System-
atic Review. J Contemp Dent Pract, 19, 1558-1564.
Cardoso, P. C., Espinosa, D. G., Mecenas, P., Flores-Mir, C. &
Normando, D. 2020. Pain level between clear aligners and fixed
appliances: a systematic review. Prog Orthod, 21, 3.
Djeu, G., Shelton, C. & Maganzini, A. 2005. Outcome assessment
of Invisalign and traditional orthodontic treatment compared with
the American Board of Orthodontics objective grading system. Am
J Orthod Dentofacial Orthop, 128, 292-8; discussion 298.
Elhaddaoui, R., Qoraich, H. S., Bahije, L. & Zaoui, F. 2017. Orth-
odontic aligners and root resorption: A systematic review. Int
Orthod, 15, 1-12.
Fang, X., Qi, R. & Liu, C. 2019. Root resorption in orthodontic
treatment with clear aligners: A systematic review and meta-analy-
sis. Orthod Craniofac Res, 22, 259-269.
Gandhi, V., Mehta, S., Gauthier, M., Mu, J., Kuo, C. L., Nanda, R. &
Yadav, S. 2021. Comparison of external apical root resorption with
clear aligners and pre-adjusted edgewise appliances in non-extrac-
tion cases: a systematic review and meta-analysis. Eur J Orthod, 43,
15-24.
Jiang, Q., Li, J., Mei, L., Du, J., Levrini, L., Abbate, G. M. & Li, H.
2018. Periodontal health during orthodontic treatment with clear
aligners and fixed appliances: A meta-analysis. J Am Dent Assoc,
149, 712-720.e12.
Karkhanechi, M., Chow, D., Sipkin, J., Sherman, D., Boylan, R. J.,
Norman, R. G., Craig, R. G. & Cisneros, G. J. 2013. Periodontal
status of adult patients treated with fixed buccal appliances and
removable aligners over one year of active orthodontic therapy.
Angle Orthod, 83, 146-51.
Kravitz, N. D., Kusnoto, B., Begole, E., Obrez, A. & Agran, B. 2009.
How well does Invisalign work? A prospective clinical study evalu-
ating the efficacy of tooth movement with Invisalign. Am J Orthod
Lagravère, M. O. & Flores-Mir, C. 2005. The treatment effects of
Invisalign orthodontic aligners: a systematic review. J Am Dent
Assoc, 136, 1724-9.
Malik, O. H., Mcmullin, A. & Waring, D. T. 2013. Invisible ortho-
dontics part 1: invisalign. Dent Update, 40, 203-4, 207-10, 213-5.
Papageorgiou, S. N., Koletsi, D., Iliadi, A., Peltomaki, T. & Eliades,
T. 2020. Treatment outcome with orthodontic aligners and fixed
appliances: a systematic review with meta-analyses. Eur J Orthod,
42, 331-343.
Rossini, G., Parrini, S., Castroflorio, T., Deregibus, A. & Debernar-
di, C. L. 2015a. Efficacy of clear aligners in controlling orthodontic
tooth movement: a systematic review. Angle Orthod, 85, 881-9.
Rossini, G., Parrini, S., Castroflorio, T., Deregibus, A. & Debernar-
di, C. L. 2015b. Periodontal health during clear aligners treatment:
a systematic review. Eur J Orthod, 37, 539-43.
Sheridan, J. 1994. Essix appliances: minor tooth movement with
• Improved periodontal health (Karkhanechi et al.,
2013).
• Shorter treatment duration
Disadvantages of CAT
• Poor control over root movements
• Not suitable for use in anterior-posterior discrepan-
cies greater than 2-4
• Lack of operator control

clear alligner appliances 29
divots and windows. J Clin Orthod, 28, 659-663.
Zheng, M., Liu, R., Ni, Z. & Yu, Z. 2017. Efficiency, effectiveness
and treatment stability of clear aligners: A systematic review and
meta-analysis. Orthod Craniofac Res, 20, 127-133.

5
1. Classification of Headgear
2. Components of the headgear
3. Types of maxillary retraction headgear
4. Clinical uses of retraction headgear
5. Factors influencing the effects of headgear
6. Fitting of retraction headgear
7. Problems and limitations of headgear
8. Classification of headgear injury
9. Chin cup
In this chapter
Extraoral
appliances

extraoral appliances
32
Headgear appliances generate an anteriorly or posteriorly
directed force from an extra-oral source to the upper denti-
tion (Graber et al., 2016).
In 1822, J. S. Gunnell invented occipital anchorage, a form
of headgear (Wahl, 2005). After 1850, Norman W Kings-
ley was among the first to use the extra-oral force (retrac-
tion headgear) to correct an increased overjet. In the 1920s,
headgear was discontinued as intra-oral elastics were con-
sidered as similar to headgear. Headgear was then rein-
troduced in the 1940s after the adverse effects of Class II
elastics came to light through cephalometric evaluation, i.e.,
proclination of lower incisors and retroclination of the up-
per incisors (Oppenheim, 1936). Later, the use of headgear
has declined with the widespread use of temporary anchor-
age devices (TADs) (Banks et al., 2010, Li et al., 2011).
Classification of Headgear
These include:
• Maxillary retraction headgear (Perez et al., 1980,
Graber et al., 2016).
• Maxillary protraction headgear.
• Mandibular retraction headgear such as chin cup
(Graber, 1977).
Components of the headgear
There are four components of the headgear (Almuzian et al.,
2016), these include:
• Extra-oral unit which provides anchorage to the ap-
pliance from the extra-oral source. It could be head
cap, neck strap, or chin cap; for protraction head-
gear, it is the facemask.
• Force delivery system includes a spring-loaded de-
vice for retraction headgear or a heavy force elastic
for protraction headgear. This component is usually
included in the head cap or the neck strap.
• Connecting component transmits the force to the
teeth and the supporting skeleton by connecting the
intra-oral and the extra-oral parts. The outer part of
the facebow joins to the inner part of the facebow.
• The intra-oral component of the facebow is attached
to an appliance; i.e. fixed, removable or functional
appliances. With fixed appliances, the inner part of
the facebow is inserted into headgear tube of the mo-
lar bands. Removable appliances are either attached
to tubes soldered to the molar clasps or inserted into
coils as part of the clasps. Headgear tubes can also be
embedded into the acrylic block of a functional ap-
pliance. The inner bow itself can also be embedded
in the acrylic of a functional appliance.
Types of maxillary retraction headgear
These include:
• High-pull headgear uses the occipital and parietal re-
gions for anchorage (Cobourne and DiBiase, 2015). In
theory, they produce forces that pass near the centre of
resistance of the maxillary molars (located at the trifur-
cation) (Barton, 1972). Hence, it produces an intrusive
force to the molars, which is beneficial in correcting
an anterior open bite. It also has a mild orthopaedic
effect on the maxilla by restraining the vertical and
sagittal growth (Bowden, 1978) though wearing high-
pull headgear might cause compensatory mandibular
growth and should be controlled if not desired.
• Low-pull headgear is also known as cervical headgear
and utilises the neck region for anchorage via a neck
strap. This appliance has been considered the most
common headgear appliance (Bowden, 1978) and is
mainly indicated in low angle Class II malocclusions as
it retrains the forward growth of the maxilla (O’Reilly
et al., 1993, Barton, 1972). Cervical headgear affects the
position of the mandible by extruding the maxillary
molars and allowing a clockwise rotation of the man-
dible (Barton, 1972).
• Straight/combination-pull headgear uses the occipi-
tal and neck region for anchorage via a head cap and
neck strap (Holmes et al., 1989). This is a hybrid type of
headgear, using a combination of high pull and low pull
headgear (Bowden, 1978). Theoretically, it can produce
a pure distal vector (as the extrusive and intrusive vec-
tors cancel out).
• Vertical pull headgear gains anchorage from the occipi-
tal bone and is mainly used for anterior open bite cases.
• J-Hook headgear is similar to high-pull headgear
(Bowden, 1978) and it exerts an intrusive and distal
force on the anterior maxillary teeth. It has the dis-
advantage of high friction, risk of root resorption and
binding (Almuzian et al., 2016, Proffit et al., 2006).
• Inter-landi type provides the option of variable force
direction (Graber et al., 2016) and it gives simultaneous
traction on the maxilla and mandible using J-hooks.
• Asymmetrical headgear is used when asymmetrical or
unilateral tooth movement is required, for example,
unilateral distalization (Martina et al., 1988). There
are different designs of asymmetrical headgear, such
as asymmetric length of the outer bow, an asymmet-
ric joint position between the outer and inner bow and
dual asymmetry (Chi et al., 2012).
Clinical uses of retraction headgear
These include:
1. Reinforcement of anchorage in an antero-posterior and
vertical direction (Ma et al., 2008).

extraoral appliances 33
2. Active dental movement such as:
• Distalisation of molars (Single or multiple teeth) up
to 2.5mm (Haas, 2000, Atherton et al., 2002).
• Headgear can be used to upright molars and relieve
impaction of first molars, secondary to premature
loss of deciduous teeth (Bjerklin, 1984).
• Asymmetric molar movement is accomplished us-
ing an asymmetric headgear (Martina et al., 1988).
• The intrusion of molars through the intrusive vector
of high-pull headgear (Firouz et al., 1992).
• Extrusion of molars using cervical headgear.
• Although no longer common, J-hook headgear can
retract maxillary canines and intrude upper anterior
teeth (Perez et al., 1980).
3. Skeletal changes such as:
• Skeletal growth modification (O’Reilly et al., 1993,
Houston, 1988) for management of Class II skeletal
problems through maxillary restraint (Antonarakis
and Kiliaridis, 2007) along with dentoalveolar effects
(de Oliveira et al., 2007). According to a systematic
review by Papageorgiou and colleagues, headgear
is a viable treatment option to modify the sagittal
growth of the maxilla in the short term for Class II
patients with maxillary prognathism (Papageorgiou
et al., 2016). According to a Cochrane review by
Batista and colleagues, headgear produces a statis-
tically significant difference with overjet correction
(Batista et al., 2018).
• High-pull headgear combined with a twin block or
monoblock appliance can be used to treat high angle
Class II malocclusions (Parkin et al., 2001).
Factors influencing the effects of the maxillary retraction
headgear
These include:
1. The direction of force (Bowden, 1978, Proffit et al., 2006)
• Antero-posterior component: If the force passes
through the centre of the resistance, bodily move-
ment could be obtained. If the force passes above
the centre of the resistance, distal root tipping and
mesial crown tipping could be obtained. While if the
force passes below the centre of the resistance, me-
sial root tipping and distal crown tipping could be
obtained.
• Vertical component: If the force is directed above
the occlusal plane and anterior to the centre of re-
sistance, intrusion and mesial tipping could be
obtained. Extrusion and distal tipping could be
obtained if the force is directed below the occlusal
plane and anterior to the centre of resistance. If force
is directed parallel to the occlusal plane, no intru-
sion or extrusion could be obtained.
• Transverse component: Expansion or contraction
of the inner facebow arms relative to the first mo-
lar tubes may cause changes in the transverse direc-
tion. When molars are distalised, the inner bow is
expanded to coordinate the upper molars transverse
relationship with the lower molars.
2. Force magnitude and duration: The force magnitude and
duration for the different applications of headgear are de-
tailed in table 1 (Almuzian et al., 2016). Maximum growth
hormone is released in the evening and patients could have
greater orthopaedic effects if headgear is worn during this
time (Proffit et al., 2006). Therefore, headgear should ideally
be worn after dinner and not just at bedtime.
Table 1: Force magnitude and duration
Purpose M a g n i t u d e
(grams)
D u r a t i o n
(hours/day)
Anchorage 200-300 per side 10-12
Distal move-
ment
300-400 per side 12-14
Orthopaedic ef-
fect
400-500 per side 14-16
Fitting of the maxillary retraction headgear
The facebow should be adjusted so that the junction of the
inner and outer bow rests in the interlabial gap passively.
The correct size of the facebow should be selected, with the
inner bow is clear by 3-4mm from the labial teeth, and the
inner bow should also be easily inserted/removed. The in-
ner bow should be expanded by 1-2 mm to avoid potential
crossbite.
The inner bow should be of 1.13 mm diameter, while the
outer bow should be 1.45 mm for optimum rigidity (Proffit
et al., 2006, Almuzian et al., 2016). Ideally, the end of the in-
ner bow should be flush with the distal aspect of the molar
tube or extended by 1 mm.
The length of the outer bow and its relationship to the centre
of resistance and the direction of pull should be carefully
selected and adjusted to minimise unwanted dental effects,
such as distal tipping.
Problems and limitations of maxillary retraction headgear
These include:
1. Tooth-related issues such as:
• Unwanted tooth movement i.e. tipping of teeth.
• Extrusion of the molars which may cause clockwise
rotation of the mandible and worsening the Class 2

34
skeletal pattern (Burke and Jacobson, 1992).
• Buccal rolling of the maxillary molars.
• Development of crossbite on the side of active asym-
metric headgear (Martina et al., 1988).
• Root resorption is most commonly observed with
J-hook headgear (Almuzian et al., 2016).
2. Patient-related problems such as:
• Patient compliance which can be monitored using
compliance charts or a headgear calendar (Cureton
et al., 1993a, Cureton et al., 1993b).
• Growth variability can lead to poor outcomes
(Boecler et al., 1989).
• Pressure alopecia due to pressure-induced ischemia
to the scalp (Leonardi et al., 2008).
• Trauma to the face and eye which are mainly due
to accidental disengagement or recoiling injuries,
though these injuries are severe but rare conse-
quences could develop, such as ophthalmitis and
blindness (Samuels et al., 1996).
• Pain due to heavy force levels, however, non-steroi-
dal painkillers can manage it.
• Nickel allergy mainly contact dermatitis-type IV
and latex allergy.
Classification of headgear injury
These include:
• Accidental disengagement while the child is playing
(Jones and Samuels, 1994).
• Incorrect handling by the child during the insertion
or removal of the headgear.
• Deliberate release of the headgear caused by another
person or unintentional detachment of the headgear
whilst sleeping.
Chin cup
Chin cup or mandibular retraction headgear is used to treat
Class III malocclusions by retarding mandibular growth,
however, there is insufficient data regarding the chin cup
therapy (Liu et al., 2010). Catch-up growth may occur dur-
ing or after the pubertal growth spurt; this is why Chin cup
is not common in the current practice (Sugawara et al.,
1990)
According to an RCT by Abdelnaby and team, chin cup im-
proved the maxillomandibular base relationship in growing
patients with Class III malocclusions, but with little skeletal
effect (Abdelnaby and Nassar, 2010). On the other hand, a
systematic review and meta-analysis showed that chin cup
in pre-pubertal patients affect skeletal and dental cephalo-
metric variables significantly indicating a positive effect for
Class III (Chatzoudi et al., 2014).
Reverse-pull headgear or protraction facemask (PFM)
Please refer to the chapter (Reverse-pull headgear or pro-
traction facemask).
EXAM NIGHT REVIEW
Classification of Headgears
• Maxillary retraction headgear
• Mandibular retraction headgear
• Maxillary protraction headgear
Clinical uses of headgears
• Reinforcement of anchorage.
• Dental movement.
• Distalisation of molars (Single or blocks of teeth).
• Molar uprighting.
• Canine/labial segment movement.
• Asymmetric molar movement.
• Intrusion of molars.
• Extrusion of molars.
• Skeletal growth modification (Houston, 1988).
• Maxillary growth restriction.
• Mandibular growth restriction (Chin cup).
• Anterior open bite (Parkin et al., 2001).
Types of Headgears
• High-pull headgear
• Low-pull headgear
• Straight/combination-pull headgear
• J-Hook headgear
• Inter-landi type
• Asymmetric headgear
Factors influencing the effect of the headgear
• Direction of force (Bowden, 1978, Proffit et al.,
2006)
• Force magnitude
• Duration
Problems and limitations of headgear
• Tooth-related problems
• Patient-related problems

extraoral appliances 35
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dentofacial orthopedics, 127, 255-259.

reverse pull head gear or protection facemask
38
6
1. Components of PFM
2. Types of PFM
3. Indications of PFM
4. Effects of PFM
5. Treatment timing for PFM
6. Factors influencing the effect of PFM
7. Side effects of PFM therapy
8. Predictors of failure of PFM therapy
9. Different trends and techniques
10. Skeletal anchorage for maxillary protraction
11. Instructions to patients wearing PFM
12. Evidence summary regarding PFM
In this chapter
Reverse-pull
headgear or
protraction
facemask (PFM)
Written by: Mohammed Almuzian, Haris Khan and Abu Bker Reda

reverse pull head gear or protection facemask 39
Reverse-pull headgear or protraction facemask (PFM)
is an appliance that utilisese anterior-directed extra-oral
forces applied to teeth and skeletal structures. Elastics are
used to transfer support from an extra-oral source to teeth
via removable or fixed intra-oral appliances (Cobourne and
DiBiase, 2015).
Components of PFM
Facemask such as Delaire-type or rail-style (Petit type) are
composed of a forehead pad and chin pad connected by a
heavy steel support rod (Petit, 1983). The intra-oral compo-
nent can be an upper removable appliance, fixed appliance,
or mini-plates. Mini-plates in the zygomatic buttress region,
can also be used as skeletal anchorage to reduce dental side
effects, thus achieving skeletal protraction of the maxilla
(Yoshida et al., 2007).
The used extra-oral elastics are usually heavy latex elastics
that are changed daily. The most commonly used elastics are
350gm, but other elastics can be used depending upon how
much force is needed to be applied.
In terms of the maxillary expander, PFM is often supple-
mented by maxillary palatal expansion. The expansion is
aimed to disrupt the circum-maxillary sutures of the maxilla
and enhance the orthopaedic effect (Küçükkeleş et al., 2010).
According to the present evidence, facemask alone is equally
as effective compared to the combined maxillary expan-
sion facemask therapy (Vaughn et al., 2005, Foersch et al.,
2015). Recently, a new technique involving rapid expan-
sion combined with rapid constriction, Alternate Rapid
Maxillary Expansion, and Constriction (Alt-RAMEC), has
been combined with a protraction facemask. A systematic
review (with limited evidence) suggests that on a short-term
basis, Alt-RAMEC/PFM results in a greater skeletal sagit-
tal improvement with more maxillary protraction and less
mandibular clockwise rotation when compared to the con-
ventional approach (RME/PFM) (Almuzian et al., 2018).
Types of PFM
These include:
1. Occipital-mentum support such as Sky Hook (Freire et
al., 2012).
2. Fronto-mentum support such as:
• Protraction headgear by Hickham (Hickham and
Miethke, 1991).
• Facemask of Delaire (Kiliçoĝlu and Kirliç, 1998) in
which the forehead cap and chin cap are connected
with a wire to the front of the mouth and provide
elastic attachment.
• Tubinger model is a modified type of Delaire, con-
sisting of a chin cup from which two rods arise and
join the forehead strap.
• Petit-type facemask (Aileni and Rachala, 2011) con-
sists of a chin cup and forehead cap with a single
compact rod running in the middle joining the two
parts.
3. Front-infraorbital support (Proffit et al., 2006) such as
Grummons.
The Delaire and Petit (rail-type) are used most frequently as
the former has good stability, but it is bulky and can cause
problems whilst sleeping or wearing glasses. The rail type is
more comfortable while sleeping and less difficult to adjust.
Both plastic forehead and chin cup may require relining with
an adhesive-backed fabric lining to improve fit and to reduce
skin irritation.
Indications of PFM
These include:
1. Class 3 malocclusion cases with maxillary hypoplasia
(Proffit et al., 2006) at the prepubertal phase which is charac-
terised by:
• Minor to a moderate skeletal discrepancy.
• Overjet is not less than -2mm or an edge to edge in-
cisor relationship.
• Proclined lower incisors.
• Retroclined upper incisors.
• Low facial height.
• Functional anterior mandibular displacement.
2. Congenital facial deformities, i.e. Pierre Robin sequence
or cleft lip and palate (Green et al., 2019).
3. Provision of anterior anchorage in hypodontia cases.
4. Stabilisation secondary to maxillary osteotomy/distrac-
tion osteogenesis.
Effects of PFM
These include:
Dental effects such as:
• Proclination of maxillary incisors (Parayaruthottam
et al., 2018).
• Mesialisation and extrusion of maxillary molars
(Clemente et al., 2018).
• Retrusion of lower incisors.
• Traction, protraction of single or groups of teeth
(Küçükkeleş et al., 2010).
Skeletal effects (growth modification) such as:
• Maxillary enhancement by apposition of bone

40
found at the maxillary tuberosity following maxil-
lary protraction (Baccetti et al., 1998). With con-
ventional RME and facemask combination, 1.5 to 2
mm maxilla advancement can be achieved; however,
4-5mm of advancement can be obtained using skel-
etal anchorage. According to a systematic review,
TADs-supported facemask can increase the skeletal
effects (Feng et al., 2012b). Moreover, it is possible to
achieve 3-12 mm of maxillary advancement by sur-
gically-assisted protraction (by incomplete LeFort
I) (Proffit et al., 2006). A multi-centre RCT showed
that almost two thirds (68%) of patients whom PFM
treated maintained the positive overjet after six-year
follow-up (Mandall et al ., 2016). Initially, skeletal
effects were clinically and statistically more signifi-
cant in the PFM group when compared to the con-
trol group; however, at a six-year review, no clinical
or statistical skeletal difference was found between
PFM and controls. A six-year follow-up, a statisti-
cally significant finding was the need for orthogna-
thic surgery; it was reduced in the PFM group at 1/3
of patients requiring orthognathic surgery, whereas,
in the control group, 2/3 of patients required it or-
thognathic surgery (Mandall et al ., 2016).
• Mandibular suppression/redirection includes clock-
wise rotation of the mandible. This downward and
backward rotation can cause an increase in the verti-
cal facial dimensions and generate lip incompetence
(Baek et al., 2010, Clemente et al., 2018).
To summarise, PFM therapy will result in the forward
movement of the maxillary complex plus downward and
backward rotation of the mandible, subsequently, this
will increases the SNA angle, decreases the SNB angle,
and increases in the ANB angle (Yang et al., 2011, Co-
bourne et al., 2012)
Treatment timing for PFM
Studies suggested PFM intervention as Class 3 growth modi-
fication depends:
• Dental age: The treatment results are better in the
early mixed dentition than in the late mixed denti-
tion (Baccetti et al., 1998). The ideal time is during
the primary dentition or the early mixed dentition
period (permanent maxillary central incisors have
erupted) (Wells et al., 2006).
• Skeletal age: Maxillary expansion and protraction
are effective during the CS1 or CS2 stage of CVs
growth (Baccetti et al., 2005).
• Chronological age: Successful forward positioning
of maxilla should ideally be undertaken by the age of
eight. Beyond that period, dental effects overwhelm
the skeletal effect (Mermigos et al., 1990). A meta-
analysis concluded that PFM is less effective in pa-
tients greater than ten years of age (Kim et al., 1999).
Another study suggested that the age at which treat-
ment is started does not affect the long-term success
for patients younger than ten years, though the suc-
cess of the treatment decreases after this age (Wells
et al., 2006). According to a multicenter randomised
clinical trial, early PFM is skeletally and dentally ef-
fective for patients younger than ten (Mandall et al.,
2010).
Factors influencing the effect of PFM
These include:
• Position of force: The force vector should pass
through the centre of resistance of the maxilla (Stag-
gers et al., 1992). The point of application of the force
should be distal to the lateral incisors located in the
canine-premolar area (Petit, 1983)
• Position and direction of force: The force vector
should be inclined at an angle of 20-30° to the oc-
clusal plane (Figure 1) (Petit, 1983).
• Duration of force: Ideally, 14-16 hours a day or as
close as 24 hours as possible (McNamara, 1987, Co-
bourne and DiBiase, 2015). Others suggest that PFM
should be worn full-time for 4-6 months and then
during night-time (Mandall et al., 2016, Graber et
al., 2016).
• The magnitude of force: To achieve an orthopaedic
effect, a force of 300-500 grams per side is used (Ver-
don et al. 1989). To protract the buccal segment, 250
grams per side is used (Nanda, 1980), while a force
of 200 grams per side is the recommended force
level with bone-anchored maxillary traction (Clem-
ente et al., 2018).
According to a systematic review, there is no scientific
evidence that would allow for the definition of adequate
parameters for force magnitude, direction, and duration for
maxillary protraction facemask treatment in Class 3 patients
(Yepes et al., 2014).

Figure ( 1 ): Elastics directed 20-30o below the occlusal
plane to reduce backward rotation of the maxilla
Side effects of PFM therapy
These include:
• Proclination of upper anterior teeth.
• Retroclination of lower anterior incisor.
• Overbite reduction / open bite tendency.
• Downward and backward rotation of the mandible.
• Irritation of lips due to elastics (solution: using
crossed over elastics to prevent catching or interfer-
ence with the corners of the lips).
• Irritation of forehead or chin (solution: adding/
changing soft padding).
• PFM doesn't cause TMD (Mandall et al., 2010)
Predictors of failure of PFM therapy
These include:
• Anterior positioning of the mandible relative to the
cranial base (Ghiz et al., 2005).
• Increased length of the mandibular ramus and body
(Wells et al., 2006).
• Increased gonial angle.
• Vertical mandibular growth pattern and downward
and backward rotation of the mandible, i.e. increases
vertical facial height.
Different trends and techniques
Since the skeletal effects secondary to PFM therapy decrease
with age, different techniques have been used in combina-
tion with PFM therapy, such as:
• Ankylosed deciduous canines (Kokich et al., 1985).
• Onplants (Hong et al., 2005).
• Osteointegrated implants (Singer et al., 2000).
• Orthodontic mini-screws (Wilmes et al., 2010).
• Mini-plates in the zygomatic region (Kircelli and
Pektas, 2008, Ağlarcı et al., 2016).
• Bone Anchored Maxillary Protraction (Clemente et
al., 2018).
Skeletal anchorage for maxillary protraction
TAD anchored PFM appliances may reduce skeletal and
dental side effects compared with tooth-anchored maxillary
protraction (Feng et al., 2012a).
According to a systematic review, bone and dentoalveolar
anchored dentofacial orthopaedics for Class III malocclu-
sion effectively correct a negative overjet (Morales-Fernan-
dez et al., 2013).
Bone anchored intermaxillary traction (BAIMT) is also
used to correct Class III malocclusions. According to an
RCT, in growing patients, BAIMT appeared to be effective
in correcting mild to moderate Class III cases (Majanni and
Hajeer, 2016). For Class III treatment, miniscrew-anchored
inverted Class II appliances such as a Forsus Fatigue Resis-
tant Device (FRD) can be used. According to an RCT (Eissa
et al., 2017), the effects are primarily dentoalveolar with
labial tipping of the lower incisors.
Another RCT showed that miniscrew anchored FRD could
effectively increase maxillary forward growth (Eissa et al.,
2018) though it did not prevent the mesial movement of the
maxillary dentition as a significant amount of lower incisor
retroclination was observed. Significant aesthetic improve-
ment of the facial profile was achieved primarily because of
upper and lower lip retrusion (Eissa et al., 2018).
Instructions to patients wearing PFM
Patients should be instructed to:
• Remove the elastics before the metal frame.
• Change the elastics daily.
• Never wear PFM while playing contact sports or any
rough games.
• PFM should be removed while brushing and eating.
• Brushing teeth for at least three minutes with fluo-

42
ride toothpaste is essential. To protect the teeth fur-
ther, an alcohol-free fluoride rinse should be used.
• If any part of the PFM comes off, it is important to
report to the orthodontist immediately.
• PFM should be brought along in each appointment.
Evidence summary regarding PFM
• There is controversy in the literature regarding us-
ing RME and protraction headgear (Kim et al., 1999,
Vaughn et al., 2005, Foersch et al., 2015).
• According to a systematic review, limited evidence
suggests that on a short-term basis, Alt-RAMEC/
PFM results in a greater skeletal sagittal improve-
ment with more maxillary protraction and less man-
dibular clockwise rotation when compared to the
conventional approach (RME/PFM) (Almuzian et
al., 2018).
• According to the RCT, the ideal time for Class 3
growth modification with facemask is before ten
years of age (Kim et al., 1999, Mandall et al., 2010)
• According to a systematic review, TADs-supported
facemask can be used to increase skeletal protrac-
tion effects (Feng et al., 2012b).
• According to a systematic review, there is no scien-
tific evidence adequate parameters for force magni-
tude, direction, and duration for maxillary protrac-
tion facemask treatment in Class III patients (Yepes
et al., 2014).
EXAM NIGHT REVIEW
Definition: An appliance which uses anterior directed extra-
oral forces to teeth and skeletal structures
Types
1. Occipital-mentum support
2. Fronto-mentum support:
• Protraction headgear by Hickham (Hickham and
Miethke, 1991)
• Facemask of Delaire (Kiliçoĝlu and Kirliç, 1998)
• Tubinger model
• Petit-type facemask (Aileni and Rachala, 2011)
3. Front-infraorbital support (Proffit et al., 2006)
Effects
Dental
• Proclination of upper incisors
• Mesialisation and extrusion of maxillary molars
• Retroclination of lower incisors
• Traction, protraction of single or groups of teeth
Skeletal (growth modification)
1. Maxillary enhancement
2. Mandibular redirection
Factors influencing the effects
• Duration of force: 14-16 hours a day (Verdon 1989)
• The magnitude of force orthopaedic effect: 300-500
grams per side
• Direction of force
Timing
Dental age: Ideal time is during the primary dentition or the
early mixed dentition when central incisors erupt at approx-
imately eight years of age (Wells et al., 2006)
Skeletal age: CS1 or CS2 ( Baccetti et al., 2005)
Chronological age: Before 10 years ( Kim et al., 1999, Man-
dall et al., 2016 )

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7
1. The Nance appliance
2. The lower lingual arch
3. Clinical steps
4. Indications for transpalatal, Nance and lingual arches
5. Common complications
In this chapter
Auxiliary arches

auxiliary arches
46
Transpalatal arch (TPA) is a stainless-steel wire connect-
ing the maxillary molars during fixed appliance orthodontic
treatment to assist with anchorage reinforcement. Although
the term lingual arch is reserved for the lower arch in most
countries, in North America, arches used for the lower and
upper dentition are also termed lingual arches.
The transpalatal arch (TPA) was originally described by
Robert Goshgarian (Goshgarian, 1974). It is constructed
from 0.9- or 1.25 mm stainless steel wire that crosses the
palatal vault, connecting one molar or premolar to the
contralateral tooth. This connection can be fixed by welding/
soldering or removable by insertion into a lingual sheath
of the molar bands. The molar band sheaths are known as
Wilson tube or Mershon attachments (Tsibel and Kuftinec,
2004, Valentin Moutaftchiev, 2009).
A modification of the attachment involves bonding the pala-
tal wire directly to the lingual surface of the molars (Tsibel
and Kuftinec, 2004).
Although the TPA does not provide absolute sagittal
(antero-posterior) anchorage, it is used as an adjunct appli-
ance during orthodontic treatment to control anchorage in
the vertical and transverse dimensions.
The Nance appliance
The Nance appliance or Nance palatal arch (NPA) is a modi-
fied TPA by adding acrylic for the palatal vault. The depth
and width of the palate contribute to a potential increase
in anchorage. NPA could be considered one of the earliest
modifications of the TPA, first described in 1947 (Nance,
1947).
The palatal wire is welded/soldered to the molar bands. It is
connected anteriorly by an acrylic button positioned in the
highest part of the palatal vault resting on non‐compress-
ible mucosa. Anatomically, a shallow and wide palate has
less anchorage potential than that of a deep-vaulted palate.
The button may be made of acrylic heat-cured, cold-cured,
or light-cured. Light-cured composite has also been used
(Prakash et al., 2011).
The lower lingual arch
The lingual arch was used extensively by Nance in the mid-
1940s (Nance, 1947). It consists of 0.9mm diameter wire
as the palatal arch. The stainless-steel wire can be either
welded/ soldered to molar bands or inserted into molar
sheaths and removable, or bonded directly to the lingual
surface of lower molars.
Modifications in wire construction allow direct attachments
of exposed teeth to the arch to improve patient comfort and
allow initial traction. The wire diameter can be increased
where greater rigidity is required. However, a study by
Owais et al.(Owais et al., 2011) showed that when using 1.25
mm wire compared with 0.9 mm, the increased wire stiff-
ness resulted in increased forces on the lower incisors and
first molars. Consequently, more proclination of the incisors
and E-space loss may occur. Additionally, the increase in
wire stiffness of the lingual arch resulted in higher cementa-
tion failure and wire breakage (Owais et al., 2011).
Clinical steps
The clinical steps involved in constructing all types of
transpalatal and lingual arches are similar. It is best to fit the
appliance before extractions are undertaken, or active orth-
odontic treatment is commenced to avoid tooth movement,
making the appliance fitting difficult with potential tooth
movement. The traditional clinical steps include placing
separators for 5-7days (Hansen and Tzou, 2006) for molar
bands to fit well.
When selecting bands, it is common to choose bands which
are one size bigger since the lumen of the band can reduce
during the laboratory welding and soldering procedures.
An impression is then taken over the bands.The bands are
repositioned in the impression and decontaminated before
being transported to the laboratory.
When the molars are rotated, this makes band placement
difficult, and so four options are available:
• Positioning the band in an offset position so that a rigid
stainless-steel wire can easily pass passively through
the molar tube bilaterally. This requires the bands to be
repositioned to the correct axial position after molar
derotation.
• An initial sectional fixed appliance to derotate the mo-
lars before construction the transpalatal or lingual arch.
• Placing the molar bands in the conventional (correct)
position with adjustment and activation of the appliance
at the cementation stage to aid molar derotation.
• Using molar bands with convertible tubes allows sliding
of the non-fully seated archwire through molar tubes
and can aid molar derotation.
Indications for transpalatal, Nance and lingual arches
TPAs have great versatility, acting as a stand-alone appliance
or as an adjunct to fixed appliances. Due to the versatile de-
sign, TPAs can provide passive and active orthodontic forces
in all three dimensions.
Applications in transverse direction include:
• TPAs and lingual arches can be used to provide
transverse anchorage and arch width stabilisation in
clinical situations, such as when aligning palatally
impacted maxillary canines (Fleming et al., 2010).
• TPAs are effective as a holding appliance or a retain-
er after active maxillary expansion with a quad-helix

auxiliary arches 47
or RME.
• For patients with a cleft alveolus, the TPA can also
be used to maintain the form of the expanded arch
prior to alveolar bone grafting (Harris and Reynolds,
1991).
• Another traditional use of TPA in the transverse di-
mension is as an adjunctive appliance in segmental
Burstone arch (intrusion) mechanics to correct ante-
rior deep bites or to decompensate the anterior seg-
ment (in the case of a skeletal AOB) before proceed-
ing with a two pieces Le Fort I osteotomy (Burstone,
1966). The TPA counteracts the buccal tipping of the
crown of the molars during intrusion of the anterior
teeth.
• A TPA in combination with a fixed functional appli-
ance can also be used to counteract the buccal forces
applied when using Class II bite correctors (Rothen-
berg et al., 2004).
• Although TPAs have been advocated as an adjunct
to headgear, to reduce the buccal tipping of molars
and palatal cusp extrusion during molar distalisa-
tion (Baldini and Luder, 1982), a subsequent study
showed no difference between the use of headgear
with or without a TPA during molar distalisation
(Wise et al., 1994).
• More recently, the use of temporary anchorage de-
vices (TADs) to correct anterior open bites has been
reported (Cousley, 2010). A TPA is frequently used
to control molar tipping where posterior teeth are
intruded using TADs.
• TPA can be used as a habit-deterrent in persistent
thumb and digit suckers (hay-rake). This requires
soldering or welding a crib to the TPA (Larsson,
1988).
• TPA can be used as space maintenance secondary
to bilateral loss of primary molars. A TPA is also in-
dicated where extractions of the deciduous molars
are planned to harness the Leeway space. However,
one of the potential problems when using a lingual
arch as a space maintainer is the interference of the
wire with the erupting premolars. A modification of
this has been suggested, which involves soldering
the wire on the buccal surface of the molars and al-
lowing it to pass along the buccal vestibule before it
passes over the canine embrasure to run behind the
lower incisors (White, 2012).
• TPAs can be used actively to expand or constrict the
dental arches, similar to a quad-helix appliance. In
this situation, the TPA can be expanded by 3-4mm
to provide a force of 200gm resulting in an expan-
sion of the maxillary arch. It can also be constricted
by the same amount to aid in the arch constriction
(Ingervall et al., 1995).
• Furthermore, TPAs can be used for distalisation
of the molars unilaterally or bilaterally to correct a
mild Class II molar relationship. This is achieved
by activating the V-shaped bend in the TPA as de-
scribed by Rebellato (Rebellato, 1995), where unilat-
eral distalisation is required; it is better to reinforce
the anchor side using headgear, placing torque in the
archwire or use temporary anchorage devices (Re-
bellato, 1995, Ten Hoeve, 1985, Cooke and Wreakes,
1978, Dahlquist et al., 1996).
Applications in vertical direction such as:
• A TPA constructed away from the palate by 5mm
may introduce some intrusive effect by the tongue
on the molars, which can correct or control the over-
eruption of maxillary molars (Goshgarian, 1974).
Wise et al. (Wise et al., 1994), in a retrospective
study, found that when compared with controls, a
TPA can control the maxillary vertical growth.
• The further development of the traditional TPA in-
corporates finger or ballista springs to aid the erup-
tion of impacted maxillary canines (Fleming et al.,
2010). The acrylic buttons in these cases are vertical-
ly positioned in the palatal vault to provide vertical
anchorage and allow a ballista spring to be embed-
ded and activated to extrude the canine. However,
the spring can be directly soldered onto the TPA and
activated to extrude a deeply-impacted canine.
• Lingual arches can be used to provide attachment to
extrude multiple teeth after multiple failures of erup-
tion associated with conditions such as Cleidocrani-
al Dysplasia (Becker et al., 1997a, Becker et al., 1996,
Becker et al., 1997b, Richardson and Swinson, 1987,
Hall and Hyland, 1978, Smylski et al., 1974).
• TPAs can provide an attachment for other fixed ap-
pliance auxiliaries. A modified Nance appliance with
an anteriorly-positioned acrylic button can provide
a ﬁxed acrylic flat anterior bite plane to treat deep
anterior overbite (Prakash et al., 2011).
Common complications
Table 2 summerises the common complications of TPA.

auxiliary arches
48
Table 2: Common complications of TPA
Complication Comment
Breakage and cement failure Breakage and cementation failure is approximately 2% and 30%, respectively, and
it is common with large diameter wires (Owais et al., 2011, Fathian et al., 2007,
Qudeimat and Fayle, 1998, Moore and Kennedy, 2006, Rajab, 2002)
Oral hygiene difficulties Especially Nance appliance in deterioration underneath the acrylic crib leading
to inflammation of the palate (Singh et al., 2009).
Unwanted changes in lower arch width.
(Lingual arch)
Increase in intercanine width as the canines migrate distally and the proclina-
tion of lower incisors as a result of the reciprocal force on the lingual surface of
lower incisors (Brennan and Gianelly, 2000, Villalobos et al., 2000, De Baets and
Chiarini, 1995, Rebellato et al., 1997).
Poor patient tolerance Especially Nance appliance in comparison with TPA and other method of an-
chorage reinforcement.
Impinging the palate as the molars move
mesially.
Especially the loop of the TPA (Figure 21 and 22).
Increase of risk of root resorption As TPA puts the roots of the anchor units against the cortical bone plate (Top-
kara et al., 2012).
Frequent need for its removal during
space closing mechanics.
To overcome this potential problem, a combi/TPA/Nance appliance can be used
(Figure 23). The Nance button portion of the arch can be removed during space
closure whilst leaving the TPA portion in situ to provide some A–P anchorage
(Yuan et al., 2012).
Other appli-
ances
Findings Year Authors
No appli-
ance (con-
trol)
Mean anchorage loss of 4.1 mm and 4.5mm was found in association with
the TPA and the control group respectively.
2008 Zablocki and McNamara
(Zablocki et al., 2008)
Onplant,
TADs & HG
Anchorage loss in the TPA group during the initial alignment stage was ap-
proximately 2 mm compared to1.6 mm in the HG group, while the anchor-
age was stable in the TPA group from the start until the end of treatment.
2008 Feldmann and Bond-
emark (Feldmann and
Bondemark, 2008)
Nance and
TPA appli-
ances
Both appliances are moderately effective in preserving anchorage (anchor-
age loss of around 1mm over six months) and there was no difference in
anchorage support between the groups but TPA was well tolerated by the
patient
2010 Stivaros et al.(Stivaros et
al., 2010)
TADs 2.5 mm of mesial movement of the upper first permanent molars in the TPA
group while the TADs group provided absolute anchorage
2012 Sharma et al.
(Sharma et al., 2012).
Nance,
TADs, and
headgear
No statistical significance between the three methods in providing anchor-
age
2014 Sandler et al(Sandler et
al., 2014)
TPA According to a systematic review, TPA alone cannot provide maximum
anchorage during anterior teeth retraction in extraction cases and subse-
quently should not be recommended for this purpose.
2017 Diar-Bakirly et al. (Diar-
Bakirly et al., 2017)
Nance and
TPA appli-
ances
Mini implants provide better anchorage than Nance and TPA appliances
(systematic reviews)
2018
&
2019
Becker (Becker et al.,
2018)
Alharbi (Alharbi et al.,
2019)

auxiliary arches 49
Applications in antero-posterior direction such as:
• A Nance palatal arch can be used to provide anchor-
age to distalise the molars as part of the Pendulum
Appliance (Hilgers, 1992), rapid molar distalisation
(REF), distal jet (Carano et al., 2002, Carano et al.,
1996), Jones Jig (Jones and White, 1992, Patel et al.,
2009, Paul et al., 2002) and the Lokar Distalising Ap-
pliance (Lokar, 1994, McSherry and Bradley, 2000).
Once distalisation has been achieved, the Nance ap-
pliance is replaced by a TPA to maintain the molar
position and space gained (Prakash et al., 2011).
• The most common use of a TPA is to minimise an-
chorage loss during fixed appliance treatment. This
is done by bringing the roots of the upper molars
in contact with cortical bone (cortical anchorage),
which is resistant to remodelling and therefore pro-
vides additional anchorage. The loop should be di-
rected posteriorly if the TPA provides antero-poste-
rior anchorage.
• Recent studies that investigated the effectiveness of
the TPA for anchorage reinforcement and found that
a TPA is moderately successful for anchorage rein-
forcement compared with other methods of anchor-
age reinforcement (Table 1).
• According to a systematic review by (Viglianisi,
2010), lower lingual arches are an effective space
maintenance method and prevent mesial molar
movement and lingual tipping of incisors.
EXAM NIGHT REVIEW
The transpalatal arch
0.9- or 1.25-mm S/S wire connecting the maxillary molars
for anchorage reinforcement, described by Robert Goshgar-
ian
• Connection can be fixed (welding/soldering) or re-
movable
• Provide anchorage in vertical and transverse dimen-
sions.
The Nance appliance
• Palatal wire is welded/soldered to the molar bands
and is connected anteriorly by an acrylic button po-
sitioned on the non‐compressible mucosa.
The lower lingual arch
• 0.9mm wire either welded/soldered to molar bands,
inserted into molar sheaths, or bonded directly.
Indications for transpalatal, Nance and lingual arches
Transverse dimension
• Provide transverse anchorage.
• Retainer after active maxillary expansion.
• Maintain the form of the expanded arch cleft alveo-
lus patients.
• Adjunctive appliance in segmental Burstone arch
• To counteract the buccal forces applied when using
Class II bite correctors.
• To control molar tipping when posterior teeth are
intruded
• Transverse anchorage for the treatment of palatally-
displaced canines (PDC).
• Habit-deterrent for persistent thumb and digit-
suckers.
• Bilateral space maintenance
• Actively to expand or constrict the dental arches
• Distalisation of the molars unilaterally or bilaterally
Vertical dimension
• • Intrusive effect by the tongue.
• • To control the maxillary vertical growth.
• • Incorporation of finger or ballista springs
to aid the eruption of impacted maxillary canines.
• • Lingual arches can be used to provide at-
tachment to extrude multiple impacted teeth.
• Fixed acrylic flat anterior bite plane for the treat-
ment of deep bite.
Anterioposterior dimension
• A Nance palatal arch can provide anchorage to dis-
talise the molars.
• Lower lingual arches for space maintenance
• Correction of molar rotations to allow easy inser-
tion of the HG inner bow can be achieved using a
TPA.
• De-rotation movement might provide additional
arch length.
• Anti-rotation effect on molars during incisor retrac-
tion.
Common complications of TPA
Breakage and cement failure, oral hygiene difficulties, un-
wanted changes in lower arch width by a lower lingual arch,
poor patient tolerance, impinging the palate as the molars
move mesially. Increase the risk of root resorption and fre-
quent need for its removal during space closing mechanics.

auxiliary arches
50
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8
1. Indication
2. Limitations and Contraindications
3. Decision Making
4. Clinical Consideration
In this chapter
Molar
distalization
appliances

molar distalization appliances
54
Molar distalization is the process of moving posterior
teeth backwards (posteriorly) and lengthening the dental
arch length. It is commonly used to correct Class 2 maloc-
clusions where maxillary dento-alveolar or skeletal protru-
sion is present (Benson et al., 2007, Flores-Mir et al., 2013).
Indications
These include:
• To correct Class 2 molar relationship, up to ½ unit
with conventional method and three-quarter unit
with mini-implant supported methods (Keles and
Sayinsu, 2000, Cobourne and DiBiase, 2015)
• To decrease a mild to moderately increased overjet
(Malik et al., 2012).
• To correct a deviated midline (Holmes et al., 1989).
• To create space for the spontaneous eruption of ec-
topic canines (Baccetti et al., 2008).
• For regaining space lost secondary to early loss of
the deciduous molars (Kennedy and Turley, 1987).
• Uprighting the maxillary first permanent molars
when impacted against maxillary deciduous second
molars (Bjerklin, 1984).
• To correct mesial inclination of the permanent max-
illary first molars.
Limitations and contraindications
These include:
• Cases with proclined incisors.
• Patients with a protrusive profile.
• Severe crowding, i.e., more than 6 mm.
• High Frankfort mandibular plane angle as most of
the techniques result in the extrusion of molars lead-
ing to counter-wedge effect opening of the occlusion
(Ngantung et al., 2001).
• Cases with posterior crossbite (Almuzian et al.,
2016).
• As most intra-oral appliances depend on the palate
for anchorage, molar distalization with conventional
appliances should be avoided in patients with a shal-
low palate (Gianelly et al., 1991).
• Buccally flared molars, as the techniques result in
buccal tipping. This causes a reduced overbite and
backward rotation of the mandible (Carano et al.,
2002b).
Decision making
When planning molar distalization, it is important to cons-
der key variables including:
• Required space: If greater than 3 mm of space per
side is required, either mini-implant supported
methods, or terminal molar extractions are prefer-
able.
• Hard tissue: There must be enough space for distal-
ization; otherwise, second or third molar extraction
should be planned before distalization to ensure ad-
equate space.
• Soft tissue: Particularly on the distobuccal aspect,
a clinically acceptable amount of attached gingiva
must be present after the distalization (Graber et al.,
2016).
Clinical Considerations
Controversy exists regarding the effect of the second molars.
According to a systematic review (Flores-Mir et al., 2013),
maxillary second and third molar eruption stage appears
to be minimally affect molar distalization, both linear and
angular distalization.
According to Cochrane review (Jambi et al., 2013), intra-oral
appliances are more effective than the headgear; however,
the former technqiues have the disadvantage of anterior
anchorage loss with an increased overjet. According to a
systemic review (Atherton et al., 2002a), the maximum dis-
talization movement produced by the intra-oral appliances is
not greater than 2-2.5 mm.
Molar distalization techniques
These include:
1. Mini-distalization techniques (Almuzian et al., 2016): A
variety of springs, wires and elastics can be used to achieve
minimal distalization, which is clinically indicated for par-
tially erupted and mesially impacted first permanent molars.
This can be achieved using:
• Brass wire ligatures, elastomeric separators and steel
spring clip separators (Almuzian et al., 2016).
• Halterman appliance: The appliance consists of
banded deciduous maxillary second molars, with
a soldered wire extending distally to the impacted
permanent first molar with a recurved hook on the
distal extension. An occlusal button is bonded on the
permanent molar from which an elastic chain is at-
tached to the recurved hook to distalise the molar
(Kennedy, 2007).
• Humphrey appliance: It consists of a Nance ap-
pliance on the deciduous molars and a welded ‘S’-
shaped wire spring bonded using composite to the

molar distalization appliances 55
mesial ridge of the ectopic molar (Nagaveni and
Radhika, 2010).
2. Headgear, where 300−350 grams of force per side is
applied, and the appliance is worn 12-14 hours per day.
Around 2−3 mm of molar distalization can be achieved
(Atherton et al., 2002b). Depending on the pre-treatment
overbite and vertical relationship, a high-pull, cervical-pull
or combination headgear are used (Almuzian et al., 2016).
3. Removable functional appliances in which the forces
produced by the stretch of muscles, fascia, and periodon-
tium aid in molar relationship correction. These appliances
are mainly used in treating Class 2 and Class 3 cases, and are
indicated in growing and compliant patients. Molar cor-
rection is achieved by a combination of dento-alveolar and
skeletal changes, but mainly dento-alveolar (O’Brien et al.,
2003).
4. Upper removable appliance or a nudger appliance
incorporates a 0.6 mm palatal finger spring or a screw as
an active component. A Southend clasp on the incisors and
Adam’s clasps on the molars and premolars are added for
retention. Anchorage is provided by the palatal vault. An
anterior or posterior biteplate may be needed to disengage
the occlusion and allow the tipped molar to be uprighted.
There is a resultant increase in the overjet due to anterior
anchorage loss.
5. Molar distalizing bow (Jeckel and Rakosi, 1991) consists
of two components; A 0.8−1.5 mm thick thermoplastic
splint is placed over the entire dentition except the teeth to
be moved, it extend into the buccal sulcus to enhance sup-
port and retention. A distalizing bow with open coil springs
applies a force to the permanent molars and is fitted into the
anterior slot embedded in the splint.
6. Class 2 elastics transfers anchorage from one arch to an-
other (Jeckel and Rakosi, 1991). In this technique, the lower
molars are pulled forward. In contrast, the upper incisors
are pulled backwards, resulting in a distalization force on the
upper molars and correction of the Class 2 molar relation-
ship. 300−350 grams of force per side is required. Class
2 mechanics are an essential part of Begg and Tip-Edge
philosophy but have the disadvantage of causing a clockwise
rotation of the occlusal plane.
7. Pendulum appliance consists of a large Nance but-
ton and it is retained by premolar bands, 0.032-inch TMA
springs inserted into palatal sheaths on the bands to distalise
the upper molars. Bonded occlusal rests on the primary
molars, or second premolars can be added for additional
retention. A midline screw can be added, to counteract a po-
tential crossbite or correct an actual crossbite, the appliance
is called a Pend-X appliance (Hilgers, 1992). An average of
8° distal tipping of molars is seen during distalization with a
pendulum appliance and 14.5° with Pendex appliance. There
is a modification with bilateral maxillary screws, but the
usage requires increased patient compliance. A force of 230
grams per side and a 60° activation are required. As a rule of
thumb, the anchorage loss represented by incisor proclina-
tion occur at a ratio of approximately 1/3-1/2 of the amount
of distalization (Byloff and Darendeliler, 1997, Ghosh and
Nanda, 1996). However, the presence of the second molars
changes the formula; consequently, if the appliance is used
after the eruption of the second molars, the anchorage loss
ratio increases to 2/3 (Hilgers, 1992). The Pendulum appli-
ance is better tolerated by patients and results in a shorter
duration of treatment in comparison to HG (Angelieri et al.,
2006).
8. Distal Jet: Bilateral tubes of 0.036-inch (internal diam-
eter) are attached to an acrylic Nance button, a coil spring
and screw clamps are slid over the tube. The wire from the
acrylic ends has a bayonet bend and inserts into a palatal
sheath of the molar band. The Nance button is attached to
a premolar band via a connecting wire. The locking mecha-
nism plays a vital role in molar distalisation and retention.
It consists of three interacting components-lock, screw, and
activation wrench. A tiny distal stop provides resistance to
the spring against compression. A force level of 240 grams
is produced using the appliance (Ngantung et al., 2001). It is
claimed that this appliance overcomes the disadvantages of
other distalization appliances by reducing the tendency for
the teeth to tip due to the fact that the forces act through or
close to the centre of rotation of the molar, hence, trans-
lating the tooth (Carano et al., 2002a). Bondemark, in a
randomised controlled trial, compared HG and the distal
jet and found that the distal jet was more effective than HG
in creating a distal movement of the maxillary first molar,
still, anchorage loss was more significant with the distal jet
(Bondemark and Karlsson, 2005). The disadvantages of the
distal jet are:
• Insufficient visibility of the screw.
• Difficulty in gaining access to the hex-head opening.
• Stripping of the activation wrench, screw or both.
• Difficulty in achieving positive engagement of the
lock on the tube to compress the spring fully.
• Anchorage loss which is expressed as an increase in
the overjet of about 0.45 mm
• A decrease in the overbite of approximately 1.28
mm, indicating extrusion of teeth. Hence, Distal Jet
should be avoided in patients with a vertical growth
pattern.
• Approximately 45% of the space created between
molars and premolars is due to the mesial move-
ment of the premolars.
• The use of Class 2 elastics to enhance anchorage re-

56
sults in extrusion of mandibular molars and mesial
movement of lower molars.
9. Jones Jig or Lokar distalizing appliance consists of a
palatal button of 0.5-inch diameter which is anchored to
the maxillary second premolars with a 0.036-inch stainless
steel wire (Brickman et al., 2000). One arm of the Jones jig
appliance is inserted into the headgear tube, and the other
fits into the molar band’s main archwire slot. Force of 70- 75
grams are delivered by a 0.040-inch Ni-Ti spring. The ac-
tive component comprises of 0.028-inch stainless steel wire
with a length of 30–35 mm, and a 3 mm long open loop is
assembled at a distance of 8 mm from the wire and divides it
into two sections, a smaller distal section and a larger mesi-
alsection (Papadopoulos et al., 2004).
10. Herbst appliance is a tooth-borne fixed functional ap-
pliance introduced in 1905 by Herbst (Herbst, 1934). Like a
conventional functional appliance, the appliance repositions
the mandible forward during function. Herbst appliance is
asscoiated with some difficulties such as speech, chewing
and swallowing problems (Pancherz, 1979). Herbst appli-
ance has a telescopic mechanism on either side of the jaws, it
is attached to bands of the maxillary permanent first molars
and the mandibular permanent first premolars, keeping
the mandible in a continuous anterior position. The overjet
correction is 56% due to skeletal change and 44% due to the
dento-alveolar change. The correction of the molar relation-
ship is the results of a combination of 43% skeletal change
and 57 % of the dento-alveolar difference (Pancherz and
Anehus-Pancherz, 1993). An increase in the mandibular
length is possibly due to condylar growth stimulation as an
adaptive response to the forward positioning of the man-
dible. The disadvantages of the Herbst appliance are:
• High cost.
• High chances of breakage and mechanical failure of
piston assemblies.
• Proclination of mandibular incisors.
• Increase in the lower facial height.
• Enamel decalcification.
• Due to the bulkiness, it causes buccal mucosal ulcer-
ation.
• Difficult removal.
11. Jasper Jumper is a tooth-borne flexible fixed functional
appliance (Blackwood, 1991) that consists of two vinyl-coat-
ed auxiliary springs attached to the maxillary first perma-
nent molars and the mandibular archwire anteriorly (Almu-
zian et al., 2016), the springs rest in the buccal sulcus and it
is attached to the distal aspect of the upper first molar and to
the lower anterior teeth. It delivers a force of 250-300 grams
(Cope et al., 1994). The short-term effects of the appliance is
60% dento-alveolar and 40% skeletal (Rankin, 1990). In the
long-term, class 2 correction is achieved mainly by dento-
alveolar movement with limited restrained to maxillary
growth, slight mandibular clockwise rotation and negligible
enhancement of mandiblular growth. Moreover, the maxil-
lary molars tip posteriorly and intrude significantly, whereas
the maxillary incisors retrocline and extrude. The man-
dibular molars move forwards, extrude and bodily move,
whereas the mandibular incisors procline and intrude. The
disadvantages of Herbst appliance are breakages (9%) along
with significant forward displacement of the mandibular
dentition (Stucki and Ingervall, 1998).
12. Eureka spring is a tooth-borne fixed inter-maxillary
appliance, it is claimed that it overcomes the problems of the
Jasper Jumper (DeVincenzo, 1997). It consists of compressed
Ni-Ti springs within a piston, the piston-cylinder attaches to
the upper molar tube via a universal joint on the headgear
tubes and the lower archwire with an open ring clamp distal
to the cuspids. The springs rest in the buccal sulcus. Eureka
springs should only be combined with a transpalatal arch
and a heavy rectangular lower archwire. The Eureka spring
achieves Class 2 correction by a dento-alveolar movement
equally distributed in the maxillary and mandibular denti-
tion (Stromeyer et al., 2002). Hence, it is crucial to add a la-
bial root torque to the lower incisors and buccal root torque
to the upper first molars to counteract the side effects. The
Eureka spring has minimal effect on the vertical dimension
(secondary changes in the occlusal plane occur due to max-
illary molars and mandibular incisor intrusion).
13. The mandibular anterior repositioning appliance
(MARA) consists of heavy ‘elbow-shaped’ wires connected
to maxillary first permanent molar tubes, bands or stainless-
steel crowns while the mandibular first permanent molar
crown has an arm attachment that engages the maxillary
molar’s elbow. The appliance is adjusted, so the mandible
elevates, and the elbow wire guides the lower first perma-
nent molars and moves the mandible forwards into a Class
I relationship. The fitting of a lingual arch aids’ the stabilisa-
tion of the lower molars. In the upper arch, a transpalatal
arch is used to stabilise the upper molars. MARA has similar
effects to the Herbst appliance but with less lower incisor
proclination (Pangrazio-Kulbersh et al., 2003).
14. Forsus fatigue resistant device is a three-piece tele-
scoping spring used for Class 2 correction. It consists of a
standard spring module, an ‘L’ pin and a push rod which is
presented in five different sizes (Ross et al., 2007). Forsus
fatigue resistant device is assembled with the appropriately
sized push rod attached directly to the lower archwire distal
to the canine teeth, and the spring is inserted into the head-
gear tube via the ‘L’ pin. This appliance has a greater than
50% rate of breakage.
15. Several adjustable inter-maxillary force (SAIF) springs
was introduced in 1995 (Jasper and McNamara Jr, 1995a).

It consists of long nickel-titanium closed coil springs that
apply Class 2 inter-maxillary traction with upper and lower
fixed appliances in place. The springs are present in two
lengths, 7mm and 10mm. The SAIF springs are not widely
used because of problems faced in appliance management,
including breakage, oral hygiene difficulties and patient
comfort.
16. AdvanSync appliance was developed in 2008 by Terry
Dischinger (Jayachandran, 2016). It is a molar-to-molar
fixed functional assembly that allows forward posture of
the mandible at the start of fixed appliance treatment. The
telescoping arms have an extended range of action and en-
able lateral excursion. The appliance is advanced by either
using the alternative screw position on the lower molars or
crimped C-rings over the pistons. The AdvanSync shows an
increase in the mandibular length by 1.4 mm, which is lesser
than the MARA appliance, it also results in a clockwise rota-
tion of the functional occlusal plane. It is claimed that the
AdvanSync appliance has a restraining effect on the maxilla,
similar to headgear (Al-Jewair et al., 2012).
17. Bite fixers consist of coil springs with a flexible core but
they are bulkier than many other fixed Class 2 devices.
18. Repelling magnets are anchored to a modified Nance,
cemented to the first premolars, and activated to move the
molars distally. Mostly samarium-cobalt and neodymium-
iron-boron magnets are used (Gianelly et al., 1989). Repel-
ling magnets produce a force of 225 grams which success-
fully allows the molars to move distally with relatively minor
anchorage loss, and requiring minimal patient compliance.
This force result in 0.75-1.5 mm of distal molar movement.
Approximately 80% of the space created is through distal
movement of the molars (Byloff and Darendeliler, 1997).
Repelling magnets produces faster results when the second
molars are unerupted (Bondemark et al., 1994). The disad-
vantages of repelling magnets are:
• The force decays over time and need of frequent re-
activation (every week).
• Magnets have to be activated weekly as the force is
dependent on the magnet alignment.
• There is a significant force drop with an increase in
the distance (Noar and Evans, 1999). The magnet
follows the inverted square law.
• Trouble of using them with other metallic appliances
such as headgear.
• There is a high initial force that decays gradually.
• Loss of force and flux in the warm environment.
• Magnets mostly have biocompatibility issues and
they are bulky
19. Mini-implants: Ismail and Johal (2002) used mini-
implants as a direct anchorage to distalise maxillary molars,
they showed suitable sites for the implant are the palatal
vault and retromolar region. If extractions of the second mo-
lars are carried out, then 4-5mm of distalization is achiev-
able (Ismail and Johal, 2002). Other uses of miniscrews in
the distalisation of the molars are supporting anchorage
and placing a distal jet appliance (Karaman et al., 2002) or
a bone anchored pendulum appliance (Kircelli et al., 2006).
According to a systematic review (Fudalej and Antoszewska,
2011), the mean distal movement of the maxillary molars
using miniscrew ranges from 3.5 to 6.4 mm, with tipping
movements ranging from 0.8° to 12.20°. According to a
meta-analysis (Grec et al., 2013), 3.34 mm and 5.10 mm of
molar distal movement can be obtained using conventional
anchorage and skeletal anchorage, respectively .
EXAM NIGHT REVIEW
Molar distalization is the process of moving posterior teeth
backwards (posteriorly) and lengthening the dental arch
length.
Indications:
The most important indication of molar distalization is
correction of ½ unit molar relationship with conventional
method and three-quarter unit with mini-implant supported
methods.Apart from this molar distalization can be used for
correction of overjet, midline deviation, spontaneous erup-
tion of ectopic canines, space gain after early loss of primary
molars and uprightining of permanant molars.
Contraindications:
Molar distalization should be avoided in cases with severe
crowding, posterior crossbite, protusive profile and high an-
gle cases as most of molar distalization appliances result in
opening of the bite.
Decision making
Following variables should be considered during the decision
making process:
• Space requirement : If more than 3 molar distalization is
required mini implant supported distalization should be pre-
ferred.
• Hard tissue: There must be enough space for distalization;
otherwise, second or third molar extraction
should be planned before distalization to ensure adequate
space.
• Soft tissue: Particularly on the distobuccal aspect,
a clinically acceptable amount of attached gingiva

58
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Clinical Considerations
Controversy exists regarding the effect of the second molars.
According to a systematic review (Flores-Mir et al., 2013),
maxillary second and third molar eruption stage appears to
be minimally affect molar distalization-both linear and angu-
lar distalization.
Molar distalization techniques
These include:
1. Mini-distalization techniques
These include brass wire ligatures, elastomeric separators,
steel spring clip separators, Halterman appliance and Hum-
phrey appliance.
2. Headgear
3. Removable functional appliances
4. Upper removable appliance
5. Molar distalizing bow
6. Class 2 elastics
7. Pendulum appliance
8. Distal Jet
9. Jones Jig or Lokar distalizing appliance
10. Herbst appliance
11. Jasper Jumper
12. Eureka spring
13. The mandibular anterior repositioning appliance
(MARA)
14. Forsus fatigue resistant device
15. Several adjustable inter-maxillary force (SAIF) springs
16. AdvanSync appliance
17. Bite fixers
18. Repelling magnets
19. Mini-implants:

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60
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9
1. Managing tooth-size discrepancies
2. Obtaining an ideal gingival level
3. Assessing the gingival form
4. Assessing the first order bend
5. Errors in second-order bend
6. Errors in third-order bend
7. Control of rebound and posturing
8. Settling of the teeth
In this chapter
Finishing
phase in
orthodontics

Finishing PHASE in orthodontics
62
The finishing stage is an essential step of orthodontic
treatment. It is necessary to spend time and effort to meet
the following aims:
• Normal overbite
• Normal overjet
• Class I incisor relationship
• Normal transverse relationship
• Correct position of upper and lower incisors
• Correct root torque
• Correct root angulation
• Correct marginal gingival level
• Absence of black triangles
• Levelled marginal ridges
• Well-proportioned upper and lower teeth
• Absence of posturing
• Maximum intercuspation with mutually protected
occlusion
Managing tooth-size discrepancies (TSD) during the fin-
ishing phase
TSD must be considered when treatment is planned ini-
tially, practically it may be managed in the finishing stage
of treatment. As a general guideline, a 2 mm of TSD noted
from Bolton analysis is the threshold for clinical signifi-
cance (Othman and Harradine, 2007).
If there is a tooth-size excess, interproximal reduction of
enamel (IPR) is the usual strategy. When the problem is a
tooth-size deficiency, it is necessary to leave space between
some teeth, which may or may not ultimately be closed by
restorations. In the case of diminutive laterals with paral-
lel axial walls, the space can be equally distributed mesial
and distal to the tooth. However, if the axial wall flares out,
then that wall should be abutted with adjacent teeth while
the other axial wall should be build-up with a composite
(Khan et al., 2014). A small tooth-size deficiency can also
be masked by altering anterior tooth position. As a rule of
thumb, spaces are utilised if incisors are positively torqued
or tipped. As the majority of cases with TSD present with
a small upper labial segment (ULS) than the lower labial
segment (LLS), it is believed that MBT prescription could
be a good choice as it has a greater difference in tip of the
ULS and LLS, 40-degree and 6-degree tip respectively. The
difference of 34 degrees means that the ULS occupies more
space than the LLS, which subsequently camouflage the
underlying TSD.
Obtaining an ideal gingival level during the finishing phase
Clinicians should aim to achieve harmonised gingival lev-
els. Ideally, the gingival margins of the central incisors and
canines should be levelled with the lateral incisor's gingival
level comparatively more incisal. Moreover, the contour of
the labial gingival margins should mimic the cementoe-
namel junctions of the teeth. If there are discrepancies in
the level of the gingival margins, an orthodontic and/ or
surgical correction should be considered. Several factors
contribute to the marginal gingival discrepancy, including:
• Actual gingival marginal discrepancy secondary to
soft tissue loss or overgrowth: The management of
this problem depends on the labial sulcular depth.
An excisional gingivectomy is indicated if a short-
er tooth has a deeper sulcus. If the sulcular depths
are equivalent, orthodontic extrusion with selective
grinding or intrusion with build-up should be con-
sidered.
• Torque discrepancy: Teeth with excessive palatal root
torque present with a coronal position of their mar-
ginal gingivae. Therefore, it is essential to address
any torque discrepancies of adjacent teeth to obtain
levelled gingival margins.
• Vertical tooth discrepancy: It is common among
adults to have a tooth or group of anterior teeth pre-
sented with non-carious hard tissue loss. This can
be evaluated by visualising the teeth from an incisal
perspective. If one incisal edge is thicker labiolin-
gually than the adjacent tooth, this may indicate that
it has been abraded. Bracket placement should be
guided by the gingival level rather than their incisal
edges to avoid creating a marginal gingival discrep-
ancy. Sometimes, this problem becomes apparent at
the finishing phase. Depending on the severity of the
discrepancy, this problem can correct orthodonti-
cally and/ or surgically or even be accepted.
Assessing the gingival form during the finishing phase
The presence of a papilla, in particular between the central
incisors, is a key aesthetic factor and should be managed
before debonding. Open gingival embrasures or black tri-
angles are usually due to:
• Abnormality in tooth shape: This can be corrected
with IPR or composite restoration,
• Abnormality in root angulation: This can be cor-
rected by uprighting movement.
• Periodontal disease can be managed by orthodontic
extrusion to relocate the papillae and/or periodontal
surgery.
Assessing the first order bend during the finishing phase
The incisal edges of the mandibular incisors/ canines are
the key to establishing proper alignment (Kokich, 2003).

Finishing PHASE in orthodontics 63
In contrast, the lingual surfaces of the maxillary incisors
and canines are used to assess an appropriate alignment
because it is the functioning surface. In the mandibular
posterior sextants, the buccal cusps of the mandibular
premolars and molars are used to determine a ideal tooth
alignment. In the maxillary posterior sextants, the central
grooves of the maxillary premolars and molars are used
to assess ideal alignment. Discrepancies in labiolingual di-
rection can be managed:
• Steiner rotation elastic wedge
• Repositioning of brackets
• Wire bending
• Abrahamian techniques: Involve placing a figure of
eight elastomeric ligatures over the tie wing, which is
desired to move away from the archwire, and ligat-
ing the other tie wing with a steel ligature.
Errors in second-order bend during the finishing phase
Errors in second-order bend can be corrected by wire
bends or bracket positioning. In contemporary practice,
bracket positioning has taken over wire bends. As a root-
paralleling moment is a crown-separating moment, the
teeth must be tied together, or the entire archwire must be
tied back against the molars to prevent spaces from open-
ing. In the Begg technique, auxiliary springs are used to
manage shortcomings of the second-order bend.
Errors in third-order bend during the finishing phase
In addition to the lateral cephalometric evaluation, errors
in the third-order bend could be identified by evaluating
the root prominence and visualising the incisors from the
occlusal view. When the incisors are viewed from an oc-
clusal perspective, the cingulum of an improperly torqued
incisor is more prominent or more visible.
Assessing root angulation during the finishing phase
During finishing, a panoramic radiograph can be obtained
to determine roots angulations. However, it is essential to
consider (Kokich, 2003):
• A panoramic radiograph is not an accurate tool due
to the associated distortions, especially in the ca-
nine/first premolar regions. Therefore, if required,
additional periapical radiographs should be used to
assess root angulations and root proximity.
• In most cases, close root proximity doesn't lead to
long term detrimental effects on the periodontal
health (Kokich, 2003).
Control of rebound and posturing during the finishing
phase
In general, some degree of relapse is noticeable after long
term uses of intermaxillary elastics. This is mainly due to
dental relapse and postural relapse of the mandible. There-
fore, it is essential to aim to overcorrect the occlusion.
When an appropriate degree of over-correction has been
achieved, the force used with the elastics should be de-
creased. In contrast, light elastics are continued full-time
for another appointment interval. Four to eight weeks be-
fore removing the orthodontic appliance, interarch elastics
should be discontinued so that changes due to rebound or
posturing can be observed. Consent should be taken from
the patient that, if required, these elastics might be used
again.
Settling of the teeth during the finishing phase
The final step of the finishing phase is achieving tight in-
terdigitation, appropriately called "settling" of the teeth.
Active settling can be achieved via artistic bends, bracket
repositioning, customised wire bending or elastic settling.
Elastic settling involves replacing the rectangular archwire
at the very end of treatment with a light round wire that
provides some freedom for movement of the teeth com-
bined with light vertical elastics to bring the teeth together.
In some cases that require minor settling, positioner or
Begg retainer could be used after debonding to allow pas-
sive settling. The indication for a positioner are:
• Minor correction following debonding and thus
"guide" the settling of the occlusion. Therefore, posi-
tioners are particularly beneficial at the end of Begg
treatment, in which stage III (the finishing phase) is
difficult.
• When the desired finish is not achieved, treatment
that is discontinued early, patients with persistent
anterior or posterior tongue habits and in deep bite
cases.
• Act as retainer and in patients who have shown ex-
cellent cooperation.
EXAM NIGHT REVIEW
Managing tooth-size discrepancies (TSD) at the finishing
phase
• 2 mm of TSD noted from a Bolton analysis is the
threshold for clinical significance (Othman and
Harradine, 2007).
• Spaces are utilised if incisors are positively torqued
and tipped.
Obtaining an ideal gingival level during the finishing
phase

Finishing PHASE in orthodontics
64
Several factors contribute to the marginal gingival discrep-
ancy, including:
• True gingival marginal discrepancy secondary to
soft tissue loss or overgrowth
• Torque
• Vertical tooth discrepancy
Open gingival embrasures or black triangles are usually
due to:
• Abnormality in tooth shape
• Abnormality in root angulation
• Periodontal disease
Discrepancies in labiolingual direction can be managed:
• Steiner rotation elastic
• Repositioning the bracket
• Wire bend
• Abrahamian techniques
Indication of positioner
• As a retainer.
• For patients who have shown excellent cooperation.
• Provide further minor correction
• They were particularly beneficial at the end of Begg
treatment
• They may be helpful in instances when the desired
finish was not achieved
• For patients with persistent anterior or posterior
tongue habits
• It is not indicated in deep bite cases.
References
Khan, S., Gill, D. & Bassi, G. S. J. D. U. 2014. Management of mi-
crodont maxillary lateral incisors. 41, 867-874.
Kokich, V. G. 2003. Excellence in finishing: modifications for the
perio-restorative patient. Seminars in Orthodontics, 9, 184-203.
Othman, S. & Harradine, N. 2007. Tooth size discrepancies in an
orthodontic population. Angle Orthod, 77, 668-74.

10
1. Principles of retention
2. Factors related to retention
3. Retention requirements
4. Types of orthodontic retainers
5. Removable retainers
6. Fixed retainers
7. Retention duration and regimen
8. Evidence summary
In this chapter
Retention and
stability in
orthodontics
Written by: Mohammed Almuzian, Haris Khan, Ahmed M. A. Mohamed and Emad Eddin Alzoubi

retention and stability in orthodontic
66
Retention is the holding of teeth, following orthodon-
tic treatment, in a treated position for some time to help
reorganise the periodontal and gingival tissues necessary to
maintain the results (Moyers, 1973).
Principles of retention
Teeth relapse in the direction of their original tooth posi-
tion due to elastic recoil of the gingival fibres and unbal-
anced tongue lip forces. Alveolar bone-bending in response
to heavy occlusal loads and masticatory stimulation of
periodontal ligaments (PDL) promote fibre reorganisation,
hence, whatever retainer is given in orthodontics should
not interfere with the physiological movement of the teeth
to help in the reorganisation of the fibres. It has been found
that:
• PDL reorganises over 3-4 months.
• Gingival (collagenous fibres) reorganise over 4- 6
months.
• Gingival (supra crestal fibres) reorganise 232 days to
over one year and
• Alveolar bone requires up to one year to remodel.
As PDL fibres reorganise in 3-4 months, it is generally
advised that retention should be full-time for the first 3-4
months, and after that, it should be maintained part-time up
to 232 days or 12 months. In growing patients, the retainer
should be worn part-time until growth has reached adult
levels (Cobourne and DiBiase, 2015), hence retention is
essential to prevent growth changes that may alter the treat-
ment results (Proffit et al., 2014a). Finally, retention is vital
to prevent relapse attributed to soft tissue imbalance.
Factors related to retention
Patient wishes, oral hygiene, and cooperation must be
considered while planning the retention phase. Duration
of retention must be carefully planned and discussed with
the patient. All associated habits should be stopped to avoid
relapse. Additionally, the following factors should be consid-
ered at the treatment planning stage:
1. Informed consent: According to the British Orthodon-
tic Scoiety (BOS) advice sheet, it is the responsibility of
the treating clinician to explain in detail the possibility of
relapse and the rationale of retention before commencement
of any orthodontic treatment.
2. Continuous facial growth: Facial growth continues
throughout life, generally in the same direction as during
adolescence, but to a much smaller degree (Behrents, 1985).
Therefore, it is recommended to retain the achieved occlu-
sion, if possible, until growth cessation with:
• Long term removable or fixed retainer to avoid low-
er incsior crowding (Sadowsky et al., 1994),
• For Class II skeletal discrepancy, modified activator
appliance or upper removable appliance with pos-
tured inclined bite plane or headgear (Wieslander,
1993).
• For Class III, either Frankle III, chin cap, or reverse
pull headgear can be provided,
• For retention of anterior open bite cases, a combina-
tion of high pull headgear plus posterior bite block
should be given, and
• For deep bite cases, the anterior bite plane appliance
can be provided.
3. Age of the patient: Some claimed that low tissue remod-
elling and soft tissue-age-related changes in adults might
indicate permanent retention to avoid relapse.
4. Occlusion at the end of treatment: There is some
evidence that a well-interdigitated occlusion aids stability at
the end of treatment because achieving an excellent occlusal
relationship will provide a favourable dentoalveolar com-
pensation (Kahl-Nieke, 1996).
5. Periodontal health and roots legnth: Permanent reten-
tion is advised in patients with periodontally compromised
dentition (Zachrisson, 1997). There is also some evidence of
an increased risk of deterioration of lower incisor alignment
post-retention in cases with root resorption or crestal bone
loss (Sharpe et al., 1987).
6. Soft tissue features: To a large extent, the soft tissues de-
fine the limitations of orthodontic tooth movement. Hence,
any change in the position of the teeth that moves them out
of the zone of soft tissue balance can increase the chance of
relapse. These include:
• Lip competency.
• Lip form.
• Lip size.
• Lip tonicity.
• Tongue size and position.
Accordingly, the lower arch form should not be changed
during treatment beyond the maximum change of 2 mm
proclination of the lower incisor and 1 mm change in lower
inter-canine width. Any change greater than above will be
prone to relapse. Vertically, the lower lip position is critical
in the stability of overjet reduction, if the lips are competent
at the end of treatment, and the lower lip rests labially to the
upper incisors and covers 1/3rd of it, stability is improved
(Melrose and Millett, 1998).
An endogenous tongue thrust is primarily neurological in
origin, resulting in the anterior position of the tongue and
excessive force exerted on swallowing. If the anterior open
bite is corrected and the tongue activity is normalised, the

retention and stability in orthodontic 67
result can be stable. However, no treatment can guarantee
stability if a true tongue thrust is present, as the primary
aetiological factor remain.
7. Original malocclusion: Retention varies according to
the treated malocclusion as below:
• Skeletal pattern: As supported by evidence, most of
the skeletal changes relapsed after 1-2 years com-
pared to controls. According to an RCT, early treat-
ment of Class 2 skeletal patterns was associated with
loss in the skeletal changes by the end of fixed ap-
pliance treatment compared with a control group
(Tulloch et al., 2004). A long-term follow-up study
of patients receiving early treatment of Class 2 mal-
occlusions with headgear and Herbst appliances,
showed that mandibular protrusive effect was lost,
and maxillary growth inhibition had continued after
growth modification (Wieslander, 1984). Moreover,
chin cup treatment of Class III malocclusions is not
stable treatment (Sugawara and Mitani, 1997). For
the above reasons, the retention of skeletally correct-
ed problems should continue until growth is ceased.
• Lower incisor irregularity: Lower incisor irregu-
larity presents most commonly in late teens to the
middle of the third decade. If an individual is un-
willing to accept significant deterioration in lower
incisor alignment following orthodontic treatment,
a permanent fixed or removable retention should be
considered.
• Anterior deep bite: Loss of positive incisor stop is
considered an aetiological factor in a deep bite case.
Achieving normal lower incisor to centroid relation
is claimed to be effective in the stability of overbite
correction(Houston, 1989). However, Kim and Little
disagree with this notation (Kim and Little, 1999).
Normal lower incisor edge to APo line has been
claimed to give good retention in deep overbite cases
(Williams, 1969). Ideally, removable appliances with
an anterior bite plate should be given until comple-
tion of growth, especially in cases with anterior
mandibular growth rotation (Proffit et al., 2014b).
• Anterior open bite (AOB): In general, AOBs tend
to relapse in approximately 20% of treated cases
(Huang, 2002). There is evidence of greater stability
of open bite correction when orthodontic treatment
is combined with extractions (Janson et al., 2006).
Extrusion of anterior teeth for AOB correction has
more relapse (40%) than molar intrusion (17-30%).
Ideally, retainers with posterior bite blocks should be
provided for AOB cases (Proffit et al., 2014b).
• Anterior crossbite: In theory, corrected anterior
crossbite is retained by the achieved positive over-
bite, otherwise, permanent retention is mandatory
to maintain the results.
• Posterior crossbite: Posterior crossbite is highly
prone to relapse. The recommended strategies (weak
evidence) by Kaplan 1988 (Kaplan, 1988) include a
minimum period of three-month retention after ac-
tive expansion. In fixed appliances a slight expansion
of the archwire, followed by achieving a maximum
intercuspation at the end of the treatment.
• Generalised spacing: It is highly prone to relapse
and requires permanent retention.
• Rotations: Fixed long-term retention is usually
preferred for derotated teeth. Ideally, the rotation
should be overcorrected to prevent relapse (a 5˚-10 ˚
of overcorrection is recommended for rotated teeth)
followed by an auxiliary surgical procedure such
as circumferential supracrestal fibrotomy or (CSF).
CSF can be undertaken in a conventional way using
a surgical scalpel to transect the gingival fibres or a
laser-aided probe. It is thought that the laser-aided
probe has several advantages, such as minor bleed-
ing, minimal swelling, and no apparent damage to
the supporting periodontal structures (BOS guide-
lines 2013). Reshaping the contact points should be
done to make them larger to improve the stability
(Tuverson, 1980).
• Diastemas: Diastema between teeth needs perma-
nent retention. Frenectomy before complete space
closure is recommended to use the scar tissue as a
natural retainer.
8. Type of treatment and teeth movement: There is con-
troversy in the literature on the type of treatment and the
potential for relapse (Kahl-Nieke, 1996, Artun et al., 1996).
Ideally, the lower intercanine width and incisor position
should be maintained. Any change of more than 2 mm in
the anteroposterior direction of incisors needs permanent
retention (Proffit et al., 2014b).
Retention requirements
Retention requirements depend on the treated malocclusion
and include:
1. Limited retention such as:
• Anterior crossbite cases in which positive overjet/
overbite has been achieved.
• Cases rely on spontaneous alignment following ex-
tractions, i.e., driftodontics or serial extractions (Ka-
plan, 1988).
• Treatment results are achieved after growth poten-
tial is over (Graber et al., 2016b).
2. Moderate retention such as:

68
bite reduction.
• An acrylic tooth can be added to an acrylic base
plate to replace a missing tooth temporarily.
• It also helps to maintain lateral expansion.
2. Begg or wraparound retainer: A modified Hawley
retainer where the labial bow extends from the distal,
proximal side of the last erupted molar to the contralateral
side. Optionally, the labial bow is soldered and hooked to a
thinner connector wire in the lateral incisor area. Its prin-
cipal advantage is that it has no clasps, therefore, wires are
not crossing the occlusion. As a result, the occlusion is free
to settle during the retention period. Apart from the known
advantages of Hawley retainers, wraparound retainers can
be used in cases with poor periodontal status.
3. Spring / Barrer retainers/Clip-on retainers: These
retainers consists of acrylate bows both labially and lingually
around the anterior six teeth. These retainers can be used to
realign minor lower incisor relapse and require the teeth set
up and realigned on the technician’s working model (Graber
et al., 2016a).
4. Moore retainer: A modification of the clip-on retainer.
Due to the risk of swallowing or aspiration associated with a
clip-on retainer, a modification that includes a lingual exten-
sion of acrylic up to the central groove of the first molars is
used.
5. Thermoplastic retainer (PFRs / VFRs): Also known as
Essix or S6, which stands for (Sheridan, Simple, Stabilising,
System for Social Sixes) (Sheridan et al., 1993). It is fabri-
cated from 0.75 mm, 1 mm, or 1.5mm polyvinyl chloride,
polypropylene, or polyethene sheets. A randomised clinical
trial showed that 0.75 mm sheets have a higher fracture rate
than 1 mm sheets, however, there was no significant differ-
ence in relapse among both thicknesses (Zhu et al., 2017).
Some evidence suggested increased wear with polypro-
pylene vacuum-formed retainers than polyethene (Raja et
al., 2014). In PFRs, a positive pressure is created above the
heated sheet, while in VFRs, negative pressure is created.
Full coverage of all teeth is essential including up to half of
the terminal molar. The advantages of thermoplastic retain-
ers are:
• Thermoplastic retainers provide pleasing aesthetics
and better control of incisor alignment than Haw-
ley-type retainers (Rowland et al., 2007).
• Thermoplastic retainers are easy to construct and
use (Sheridan et al., 1993).
• Thermoplastic retainers are more cost-effective than
Hawley retainers (Hichens et al., 2007).
• Thermoplastic retainers can also be used for active
tooth movement.
• Posterior crossbite with good inter-digitation.
• Class I, non-extraction cases, with normal tongue
and lip activity and position.
• Class I or II extraction cases, in which tongue and
lip relations have been altered, for example incisor
retraction
• Early correction of mild rotation before root forma-
tion.
• Ectopically erupted teeth, e.g. impacted canines and
supernumerary teeth.
• Class II div. 2 malocclusions (Graber et al., 2016b)
3. Permanent retention such as:
• When expansion has been carried out, particularly
in the mandibular arch
• Large generalised spacing.
• Spacing between the maxillary central incisors.
• Severe rotations.
• Severe labiolingual malposition (Graber et al.,
2016b).
Types of orthodontic retainers
There are two types of orthodontic retainers, removable and
fixed retainers.
A. Removable retainers
Removable retention appliances include:
1. Hawley retainer: The most popular retainer used in
orthodontics. It contains a labial bow, Adam clasps and an
acrylic baseplate. Theoretically, it helps in posterior occlu-
sal settling in the initial months of retention (Sauget et al.,
1997). Except for a thermoplastic retainer, it is more cost-
effective than other retainers (Hichens et al., 2007).
The labial bow of the Hawley appliance, apart from reten-
tion, has the additional benefit of closing any residual
space present between the incisors. For this, some acrylic is
needed to be removed on lingual aspects of incisors. Modifi-
cations of the labial bow of the Hawley retainer are:
• Reverse U-loops which provide better control of the
canines.
• Labial bow soldered to the molar cribs, which
means that there are fewer wires to interfere with
the occlusal settling.
• Short labial bow passes mesial to canines to avoid
extraction space opening in the canine area.
The advantages of an acrylic plate of the Hawley retainer are:
• A bite plane can be incorporated to maintain over-

• An acrylic tooth can be added to thermoplastic re-
tainers to replace a missing tooth temporarily.
• As thermoplastic retainers have bite closing effects,
they can be used in cases with a limited open bite.
• Thermoplastic retainers may be used as a nightguard
to prevent bruxism but can result in caries if not ap-
propriately cleaned.
The disadvantages of thermoplastic retainer are:
• Ineffective retainaing expansion cases, unless rein-
forced by thick wire on lingual aspects.
• Ineffective to retain extrusion movement unless
some attachment is placed on the tooth surface and
their housing is present in the retainers.
• It doesn’t allow settling of the occlusion.
• If partial Essix, which covers the anterior six teeth,
the patient may develop anterior open bite (Sheri-
dan et al., 1993).
• Increase risk of decalcification in the presence of a
cariogenic diet.
Although initial compliance is higher with thermoplastic
retainers, overall compliance with Hawley retainers is better
after 2 years post-treatment (Pratt et al., 2011). According
to a randomised controlled trial, thermoplastic retainers
were better over six months than Hawley retainers (0.5mm,
contact point displacement canine to canine) at maintain-
ing correction of maxillary and mandibular labial segments
(Rowland et al., 2007). However, a systematic review found
no evidence of the difference between Hawley and thermo-
plastic retainers (Mai et al., 2014).
6. Positioner are elastomeric or removable rubber retain-
ers preformed or custom-made. Custom made retainers are
fabricated on articulated models in which the teeth have
been sectioned and realigned to achieve the desired result.
The appliance is then formed around the teeth and the
coronal part of the gingiva. The patient is advised to wear
the appliance and practise repeated cycles of clenching then
relaxation to encourage the desired tooth movements. These
should occur in the first 3 weeks so that the positioner soon
becomes a passive retainer. The advantages of Positioner are:
• Positioner provides further minor correction fol-
lowing debonding and thus “guide” the settling of
the occlusion.
• The positioner is particularly beneficial at the end
of Begg treatment in which stage III (the finishing
phase) is complex.
• The positioner may also be helpful when the desired
finish was not achieved, or a case discontinued early.
The disadvantages of Positioner retainers are that they are
costly to make and do not hold rotational corrections or
overbite correction well. The positioner is also not popular
with patients who were of poor complaince.
7. Damon splint is a modification of Essix retainers where
upper and lower retainers are connected to make a monob-
loc. It is hard pressure formed, dual hardness/soft liner and
elastic silicone. Damon splints are used to hold inter-and
intra-maxillary corrections. Hence, they are used as a reten-
tive splint for Class II, Class III, bilateral crossbite treatment
and orthognathic cases. It is also claimed that Damon’s
splints assist in tongue training.
8. Headgear, facemask, chin cup, functional appliance and
modified activators can also be used passively as retainers at
the end of the growth modification treatment where growth
is remaining and to complete treatment in cases where it
is thought appropriate to prematurely debond the fixed
appliance in the presence of 2 or 3mm Class II discrepancy.
Bonded retainers should be fitted to retain alignment before
taking impressions for the functional retainer. Although
some clinicians advocate inclined bite planes, a more posi-
tive approach is to use Activator or Twin Block designs. In
the latter case, it is appropriate to construct the appliance to
an edge to edge relationship, reduce the vertical opening to
3mm, and keep the block interfaces upright at 90°.
B. Fixed retainers
There are several designs and types of fixed retainers, includ-
ing:
1. Fixed appliance can be left as retainers, but they accumu-
late plaque, are challenging to clean, and are unaesthetic
options for long-term retention.
2. Dental bridges can be used as retainers in hypodontia
cases only.
3. Banded retainer where bands are placed on the lower pre-
molars with a connecting soldered, heavy archwire (0.030’’)
which is closely adapted to the lingual surfaces of the lower
labial segment. A banded retainer is less acceptable to the
patient.
4. Bonded retainers, there are three types of bonded retain-
ers:
a. Rigid retainer (aka flying retainer) which is bonded on
canines only with a rigid wire touching but not bonded to
lower incisors. Rigid retainers have the following indications
(Bearn, 1995):
• Severe pre-treatment lower incisor crowding or ro-
tations.
• Planned alteration in the lower intercanine width
during treatment.
• Increased proclination of lower incisors during ac-
tive treatment.

70
• Non-extraction treatment is mildly crowded cases.
In a 5-year follow-up, mandibular 3-3 (bonded only to
canines) retainers effectively prevented relapse in 60% of
patients. However, 40% had an increase in incisor irregular-
ity (Renkema et al., 2008). A systematic review found that
canine-canine rigid bonded retainers had less failure rate
than canine-to-canine retainers bonded to all teeth (Al-
Moghrabi et al., 2016).
b. Semi-flexible retainers such as:
• Sandblasted round stainless-steel wire: which is
usually made from 0.030”-0.032” stainless-steel wire
(0.6-0.7 mm). This type of retainer has less failure
rate than a round wire retainer because of the flex-
ibility. However, no difference was found in a com-
parative study between multistrand or round wire
except more plaque accumulation with the former
retainer (Al-Nimri et al., 2009).
• Reinforced polyethene fibre material where the fi-
breglass strips are soaked in composite and bonded
to an acid-etched enamel (Karaman et al., 2002).
This technique has the advantage of reducing the
bulk of the retainer. The failure rate of this type of
retainer over three years was higher than the thick
multistrand retainer (Artun et al., 1997).
c. Flexible retainers such as:
• Orthoflex chain which is is made from gold or stain-
less steel chains.
• Multistrand or coaxial wire in 0.0155”, 0.0175”,
0.0195”, or even 0.0215” diameter. The proposed ad-
vantages of the use of multi strands wire retainers are
that the irregular surface offers increased mechani-
cal retention for the composite without the need for
the placement of retentive loops. Moreover, the flexi-
bility of the wire allows physiologic movement of the
teeth, even when several adjacent teeth are bonded
(Bearn, 1995). Additionally, a multi-strand wire pro-
vides more incisor control than a round wire (Artun
et al., 1997).
Bonded retainer placement
The conventional acid-etch technique is used in bonding
almost all types of bonded retainers. According to an RCT,
the application of resin in the bonding of lingual retainers
appears to reduce the incidence of retainer failure and the
incidence of calculus accumulation and discolouration adja-
cent to the composite pads (Bazargani et al., 2012). The most
commonly used bonding technique for bonded retainers
is the direct bonding procedure, where the composite pads
are directly placed on teeth. The indirect bonding technique
was proposed in the late 1990s as a faster alternative to the
direct bonding procedure. Indirect bonding requires lab
preparation of the composite pads on a pre-bended wire,
usually fitted with the assistance of a transferring jig or
silicon (Haydar and Haydar, 2001), though no difference
was found between direct and indirect bonding of lingual
retainers (Egli et al., 2017). In terms of bonding materials, a
randomised clinical trial found that the failure rate of lower
labial segment bonded retainers was on average 46.4% irre-
spective of chemical or light cure bonding materials (Pandis
et al., 2013).
Advantages of bonded retainers
These include:
• Easy and well tolerated by the patient.
• Do not compromise on aesthetics.
• Minimal interference with speech.
• Less reliant upon compliance than removable retain-
ers. however, a randomised clinical trial has shown
that images of relapse shown to both patients and
parents can increase compliance with the removable
retainers and decrease the chance of relapse (Lin et
al., 2015).
• Allow some physiological movement of the teeth.
• Less periodontal damages: Bonded retainers do not
seem to produce long-term periodontal problems,
although calculus can build up around them, par-
ticularly in the lower incisor region. 75% of patients
had bonded mandibular 3-3 retainers in situ after
20-29 years, without the association of periodontal
disease or caries (Booth et al., 2008)
• Good effectiveness: Although relapse in the lower
labial segment was found statistically insignificant
with both removable and fixed retainers () (Forde et
al., 2018, Atack et al., 2007), another RCT found that
bonded retainers are better at maintaining alignment
in the first 6 months after debonding than thermo-
plastic retainers (O’Rourke et al., 2016). The same
researchers followed up their sample over a period
of 18 months (O’Rourke et al., 2016) and 5 years (Al-
Moghrabi et al., 2018). during the 18 months follow
up, the degree of relapse almost became identical.
however, over a more extended period (5 years),
they concluded that fixed retainers are more effec-
tive than the removable retainers in maintaining
mandibular anterior segment alignment. However,
there was a high drop-out rate in the study. Over 5
years, the majority (90.5%) of patients with flexible
spiral wire bonded on all lower anterior had their
alignment maintained (Renkema et al., 2011).
Disadvantages of bonded retainers
These include:

• Placement is time consuming.
• Technique sensitive.
• Interference with the bite, especially in deep bite
cases.
• Potential increases in caries rate as interdental clean-
ing becomes difficult under partially failed bonding
material (Bearn, 1995).
• Interference with the settling of occlusion.
• Do not retain transverse expansion.
• Bonding failure: Some studies reported a high fail-
ure rate (23%) (Artun et al., 1997), (30%) (Renkema
et al., 2011) or as high as 46.4% (Pandis et al., 2013)
though 30% of patients with bond failures had an av-
erage of 0.81 mm increase in the incisor irregularity
(Renkema et al., 2011) this was similar to the find-
ings of another RCT (Forde et al., 2018). A systemic
review reported a 12-50% failure rate, most com-
monly between the lateral incisor and canine (Iliadi
et al., 2015).
• Fixed retainers might fail without patients knowing
until relapse occurs, which can add to the clinician’s
responsibility. Therefore, a removable backup retain-
er should also be supplied to the patient to preserve
tooth position if the fixed retainer fails.
• A fixed retainer is not efficient in maintaining ex-
traction space unless extended posteriorly. however,
this usually increases the failure rate.
• Fixed retainers mightan be deformed and become
active, resulting in some movement. A study found
that using flexible spiral wire or twist-flex retainers,
bonded to all mandibular anterior teeth, may result
in unwanted labiolingual movement or torque of the
lower anterior teeth (Katsaros et al., 2007).
Retention duration and regimen
It is generally stated that “the increased length of retainer
wear decreases relapse” (Tofeldt et al., 2007). According to
Proffit, retention should be given 3-4 months full-time and
up to 12 months part-time (Proffit et al., 2014b). Moreover,
one-year retention is beneficial for preventing relapse as
cases retained for six months had double the relapse rate
(Destang and Kerr, 2003). According to a Cochrane review,
variation among retention protocol exists among clinicians,
with insufficient research data to recommend the best clini-
cal practice (Littlewood et al., 2016).
According to a short-term follow-up RCT, patients who
wore thermoplastic retainers on a part-time basis experi-
enced similar levels of relapse to those patients who wore
them full-time (Gill et al., 2007). Another trial found no sig-
nificant difference between part-time versus full-time wear
of thermoplastic retainers and Hawley retainers in multiple
RCTs (Barlin et al., 2011, Jaderberg et al., 2012, Shawesh et
al., 2010, Thickett and Power, 2010).
Evidence summary
• Skeletal changes of growth modification both in
Class II and III are prone to relapse, which must be
considered in retention.
• An RCT showed that 0.75 mm sheets have a higher
fracture rate than 1 mm sheets. However, there was
no significant difference in a relapse in both types
(Zhu et al., 2017).
• According to an RCT over -six months, ther-
moplastic retainers were better than Hawley
retainers(Rowland et al., 2007). However, a system-
atic review found no differences between Hawley
and thermoplastic retainers (Mai et al., 2014)
• A systematic review found that a canine-only bond-
ed retainer (aka flying retainer) has a less failure rate
than a canine to canine retainer bonded to all teeth
(Al-Moghrabi et al., 2016).
• According to an RCT, the application of resin in the
bonding of lingual retainers appears to reduce the
incidence of retainer failure and the incidence of cal-
culus accumulation and discolouration adjacent to
the composite pads (Bazargani et al., 2012).
• According to another RCT, fixed retainers are more
effective than removable retainers in maintaining
mandibular anterior segment alignment. However,
there was a high drop-out rate in the study (Al-
Moghrabi et al., 2018).
• According to a systematic review, the 12-50% failure
rate was reported most commonly between the lat-
eral incisor and the canine (Iliadi et al., 2015).
• According to an RCT, over six months following
debonding, patients who wore Essix retainers part-
time experienced similar levels to those who wore
them full-time (Gill et al., 2007). But multiple RCTs
found no significant difference between part-time
versus full-time wear of thermoplastic retainers and
Hawley retainers (Barlin et al., 2011, Shawesh et al.,
2010, Thickett and Power, 2010).
• According to a Cochrane review, variation among
retention protocol exists among clinicians. insuffi-
cient research data to recommend the best clinical
practice (Littlewood et al., 2016).
• An RCT has shown that images of relapse shown to
both patients and parents can increase compliance
with retainers and decrease relapse (Lin et al., 2015)

72
EXAM NIGHT REVIEW
Why is retention necessary? To help in the reorganisation of
the periodontal and gingival tissues.
Principles of retention
• PDL reorganises over 3-4 months.
• Gingival (collagenous fibres) reorganise over 4- 6
months.
• Gingival (supra crestal fibres) reorganise 232 days to
over 1 year.
• Alveolar bone up to 1 year.
Factors Related to Retention
• Growth
• Age (Adult Patients)
• Occlusion at the End of Treatment
• Periodontal Health
• Soft Tissue Features and its Relationship to the Sta-
bility of Treatment
• Original Malocclusion
• Type of Treatment and Teeth Movement
Removable Retainers
• Hawley retainer
• Wraparound retainer or Begg retainer.
• Clip-on retainers/ Spring retainers/ Barrer retainers.
• Moore retainer.
• Thermoplastic retainer which could be either vacu-
um-formed retainer (VFR) or pressure-formed re-
tainer (PFR).
• Positioner.
• Damon Splint.
• Headgears, passive functional/ activator appliances.
Advantages of thermoplastic retainers
• Pleasing aesthetics and better control of incisor
alignment than Hawley type retainers (Rowland et
al., 2007).
• Easy to construct and use (Sheridan et al., 1993).
• Cost-effective than Hawley retainers (Hichens et al.,
2007).
• Used for active tooth movement (Lab work needed
on physical models).
• An acrylic tooth can be added to thermoplastic re-
tainers to replace a missing tooth temporarily.
• Bite closing effects. they can be used in cases with a
limited open bite.
• Used as a nightguard to prevent effects of
bruxism(Sheridan et al., 2016).
Disadvantages of thermoplastic retainers
• Ineffective to retain expansion cases
• Ineffective to retain intrusion or extrusion move-
ment
• Poor settling of the occlusion
• Increase the risk of decalcification in the presence of
a cariogenic diet.
Fixed Retainers
1. Fixed appliance
2. Dental Bridges
3. Bonded Retainers
• Rigid retainer
• Semi-flexible retainers: Flexible retainers are bond-
ed on each tooth.
• Flexible retainers (Multistrand, coaxial wire or
Chain wire)
Advantages of fixed retainers
• Easy & well tolerated by the patient
• Do not compromise on aesthetics
• Minimal interference with speech
• Less reliant upon compliance than removable re-
tainers
• Allow some physiological movement of the teeth
• Less periodontal damages
• Promising effectiveness
Disadvantages of fixed retainers
• Time-consuming
• Technique-sensitive
• Interference with the bite, especially in deep bite
cases
• Potential increases in caries rate (Bearn, 1995)
• Interference with the settling of occlusion
• Do not retain transverse expansion
• Bonding failure
• Fixed retainers might be deformed and become ac-
tive, resulting in some unwanted movement.

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FUNCTIONAL APPLIANCES
76
11
1. History of Functional Appliances
2. Theories on how functional appliances work
3. Functional appliances and airway
4. Skeletal modifications by functional appliances
5. Summary of evidence for the effect of functional appli-
ances
6. Soft tissue effects of the functional appliance
7. Indications of a functional appliance
8. Classification of functional appliances
9. Advantages of removable functional appliance
10. Disadvantages of removable functional appliance
11. Problems with functional appliances
12. Class II functional and orthopedic appliances
13. Twin block therapy
14. Activators appliances
15. Activators combined with headgear
16. Bass appliance
17. Medium opening activator
18. Dynamax appliance
19. Frankel appliance
20. Herbst Appliance
21. Jasper Jumper appliance
22. MARA (Mandibular anterior repositioning appliance)
23. Sabbagh universal spring (SUS):
24. Twin force bite corrector
25. Forsus fatigue resistant device (FRD):
26. Class III correction appliances
27. Factors affecting the choice of functional appliances
28. Recommended wear time of removable functional ap-
pliances
29. Timing of intervention using functional appliance
therapy
30. Success rates of functional appliances
31. Stability of treatment secondary to functional appliance
therapy
32. Early versus late Treatment
33. Use of functionals in the UK
In this chapter
FUNCTIONAL
APPLIANCES
Written by: Mohammed Almuzian, Haris Khan and and Emad Eddin Alzoubi

FUNCTIONAL APPLIANCES 77
Functional appliances are removable or fixed orthodon-
tic appliances that use forces generated by the stretching
of muscles, fascia, and periodontium to alter skeletal and
dental relationships (Mills, 1991). The functional develop-
ment of the jaws starts from breastfeeding and the use of
pacifier in an infant. It has been found that young children
with a history of suboptimal breastfeeding have a higher
prevalence and risk ratio for malocclusions with increased
risk of developing a class II canine relationship, posterior
crossbite, and anterior open bite (Dogramaci et al., 2017).
The claimed effects of breastfeeding and pacifier use are:
• Help to develop airway spaces.
• Apply positive downward and forward growing
forces on both upper & lower jaws.
• Suckling forces generally act to form a wide dental
arch. Suckling also promotes good swallow muscle
tone, which assists ideal jaw and airway develop-
ment.
History of Functional Appliances
In summary:
• Norman Kingsley 1879 was the first to use a remov-
able appliance to change or ‘jump’ the bite.
• The inclined bite plane was first used in the 19th
century by Catalan.
• Monobloc appliance was developed in 1902 (Robin,
1902).
• Herbst appliance was first introduced in 1910 and
then again reintroduced in 1979 by Hans Pancherz
(Pancherz and Bjerklin, 2015).
• Andreasen’s appliance was introduced by An-
dreasen and Haupl in 1936, and the term activator
was coined for this appliance (Troehler).
• Bionator was introduced by Wilhelm Balter in 1950.
• Frankel appliance was introduced by Frankel in
1966 (Frankel, 1966).
• Clark’s twin block was developed in 1977 (Clark,
2010).
Theories on how functional appliances work
Functional appliances correct sagittal jaw discrepancies
by posturing the mandible forward. This postural cor-
rection is fundamental to the appliances’ mode of ac-
tion and influences four principal regions: facial soft tis-
sues, muscles of mastication, dentition and jaws skeleton.
Functional appliances and airway
Mandibular deficiency is a factor in the reduction of oropha-
ryngeal airway dimensions, and related impaired respira-
tory function (Ozbek et al., 1998). An increase in the upper
airway volume was found after treatment with functional ap-
pliances, this difference was mainly related to the changes at
the oropharynx level, which differed significantly from what
was observed in the Class I group (Isidor et al., 2018). Sig-
nificant short-term changes in sagittal airway dimensions,
hyoid position, and tongue position were induced by func-
tional therapy of mandibular advancement in subjects with
Class 2 malocclusion and sleep-disordered breathing, when
compared with untreated controls (Pavoni et al., 2018).
Skeletal modifications by functional appliances
These include:
1. Jaw position and size: It was concluded that patients aged
9-10 and 10-12 years gain more mandibular growth than their
peers, 1.5mm/year and 1 mm/years respectively (Marschner
and Harris, 1966). However, this increase is thought to be ac-
celerated growth rather than increase in growth as the size
of mandible is genetically determined (Pancherz and Fackel,
1990).Accordingtoasystematicreview(NiuandZhou,2011),
a functional appliance can enhance mandibular growth in
the treatment of skeletal Class 2 malocclusion, mainly due to
growth of the ramus instead of changes in mandibular body
length. In an RCT (Baysal and Uysal, 2014), it was reported
that the twin block (TB) skeletal change is mainly due to man-
dibular growth, hence, it is preferred in mandibular retrogna-
thic patients. According to a systematic review (Antonarakis
and Kiliaridis, 2007), TB affects both jaws while activators and
combination appliances affect mandible and headgear effects.
Some studies show no long-term skeletal gain with Herbst
functional appliances (Pancherz and Hansen, 1986,
DeVincenzo, 1991). According to a Cochrane review by Ba-
tista (Batista et al., 2018), there is low-quality evidence for
greater ANB correction with a twin block than other appli-
ances. Removable functional appliances were more effective
in terms of ANB correction than fixed functional appliances.
2. Changing growth direction: This is mainly in the vertical
direction (Mills, 1991). Treatment with removable functional
appliances results in parallel downward positioning of the
mandible whilst treatment with semi-removable appliances
results in a backward and downward rotation of the mandible.
Extraoral appliances are not effective in controlling the lower
facial height (Novruzov et al., 2018). The mean differences in
the treatment effect of functional appliances, relative to the
untreated controls, as -0.61° per year for SNA angle, -0.61 mm
per year for anterior maxillary displacement, and +0.07° per
year for maxillary plane rotation. According to a systematic
review (Nucera et al., 2016), removable functional applianc-
es in Class 2 growing patients have a slight inhibitory effect
on the sagittal growth of the maxilla in the short term, but
they do not seem to affect the rotation of the maxillary plane.
3. Changing the position of the glenoid fossa: The glenoid

78
fossa is remodelled secondary to functional appliance therapy
(Pancherz,1991),howeverMills(Mills,1991)foundnochange
in the position of the glenoid fossa. According to a systematic
review (Al-Saleh et al., 2015), there is inconclusive evidence
on TMJ change with the use of fixed functional appliances.
Posterior displacement of the condyles and glenoid fossae
from the start to the end of treatment was found (Atresh et al.,
2018). Condylar position changes with the use of a functional
appliance with little long-term changes (Chintakanon et al.,
2000). It was also found in a systematic review (Popowich et
al., 2003) that Herbst caused little change in condyle position.
With functional mandibular advancement, disc displace-
ment was reported (Kinzinger et al., 2006a). In contrast, no
change in joint spaces was found by Kinzinger (Kinzinger et
al., 2006b).
Moreover, it was reported that the twin block is more effec-
tive in relieving joint pain, diminishing joint dysfunction,
reducing joint clicking, and eliminating muscle tenderness
in patients with anterior disc displacement with reduction
as compared to an occlusal splint (Rohida and Bhad, 2010).
Summary of evidence for the effect of functional appli-
ances
The effects of Class 2 functional appliances are mostly den-
tal with small skeletal growth modification. Skeletal effects
of Class 2 growth modification are mild restrain of maxil-
lary growth and favorable mandibular growth (Pancherz,
1984). The skeletal effects are mostly statistically signifi-
cant but clinically insignificant (Vaid et al., 2014, Koretsi
et al., 2014, Marsico et al., 2011, Zymperdikas et al., 2015).
Soft tissue effects of the functional appliance
According to a systematic review (Ren, 2007), functional
appliances produced statistically significant soft tissue ef-
fects, but their clinical significance is questionable. More ad-
vancement in soft tissue pogonion and lower lip are found
in the twin block compared to the Herbst (Baysal and Uysal,
2011). Profile silhouettes of children who had received ear-
ly orthodontic treatment for Class II malocclusion using a
twin block appliance were perceived to be more attractive
by peers than those of children who did not receive treat-
ment. According to a systematic review (Flores-Mir and Ma-
jor, 2006), soft tissue changes with an activator or bionator
are controversial using cephalometric soft tissue findings.
Furthermore, significant improvement of profile by the ad-
vancement of soft tissue chin is observed with a bonded
Herbst, followed by fixed appliance treatment (Baccetti et
al., 2009). According to a systematic review (Flores-Mir et
al., 2006) fixed functional appliances in Class II div I pa-
tients produce significant soft tissue changes in profile, but
these are not clinically significant. It was also found that
Class II div I patients in late pubertal age treated with a
fixed functional along with fixed orthodontic treatment,
and those with two maxillary premolar teeth extracted
have similar soft-tissue outcomes (Janson et al., 2017).
Indications of a functional appliance
These include:
• Interceptive appliance, e.g., large overjet with in-
creased chances of dental trauma. According to a
systematic review, children with an overjet larger
than 3 mm have approximately twice the chances
of trauma to anterior teeth than children with an
overjet smaller than 3 mm, with higher chances of
trauma for boys than girls (Nguyen et al., 1999).
• Anchorage build-up.
• Correct facial asymmetry using a hybrid appliance.
• Habit breaker appliance.
Classification of functional appliances
Functional appliances classified according to the mode of
action (Mills and Vig, 1974) into:
• Myotonic such as Harvold activator.
• Myodynamic such as Andresen appliance.
Other method of classification us according to the mode of
retention (Houston et al., 1992) and include:
• Passive tooth-borne such as Andresen appliance
• Active tooth borne such as twin block appliance
• Tissue borne such as Frankel appliance
• Component approach such as hybrid appliance (Vig
and Vig, 1986)
• Fixed functional such as Herbst appliance (Pan-
cherz, 1979).
Another classification by Professor Hunt is based on the
method of retention and this includes:
• Removable appliances such as Andreasen, appliance
Bionator appliance, Harvold appliance, medium
opening activator and function regulators (FR).
• Removable functional appliances combined with a
headgear are a good choice in high angle cases such
as a twin block (Clark, 1982) with HG, Van Beek,
Bass appliance with HG, Tauscher or headgear acti-
vator Tauscher appliance (HATA)
• Fixed functional appliances which can be subclassi-
fied into:
1. Flexible fixed functional appliance such as Jasper Jumper
appliance
2. Rigid fixed functional appliance

pliances like the Dynamax appliances, headgear with a func-
tional appliance or monobloc and Class II elastics supported
with mini plates can be used. A study by Ozbilek (Ozbilek et
al., 2017) showed that the undesirable dentoalveolar effects of
the monobloc appliance were eliminated by using miniplate
anchorage. Favorable skeletal outcomes can be achieved by
skeletal anchorage therapies, which could be an alternative
to treat skeletal Class II patients with mandibular deficiency.
Sometime, extractions is the option to correct inclinations.
3. Upper incisor retroclination: a RCT by Trenouth
(Trenouth and Desmond, 2012) advocated the use of South-
ern end clasps to prevent incisor retroclination. Head-
gear combined with the functional appliance and upper
incisor capping or ‘torqueing’ spurs (Gill and Lee, 2005)
can be used to prevent incisor retroclinations. Alterna-
tive methoids are ensuring a positive contact between
palatal acrylic and the upper incisors, and the use of high
torque prescriptions MBT brackets, and full archwire size.
• Lateral open bite: Overjet reduction can be rapid
with a functional appliances and accompanying changes in
the vertical dimension usually do not occur at the same rate,
hence, a lateral open bite is often present at the end of over-
jet reduction, particularly where the overbite was originally
increased. This problem can be minimised once the overjet
is fully reduced with selective trimming of the upper block
to allow eruption of the mandibular first molars or part-time
wear of the appliance. However, this might encourage the
lower molars to erupt more mesially, causing lower premolar
crowding as well as leading to LLS crowding. Nighttime wear
of the appliance and the use of a URA with a deep anterior bite
plane (steep and deep) to maintain the overjet and allow set-
tling of the lateral open bite can be considered. Some claimed
that Dynamax appliance and fixed functional appliances pro-
duce less open bite problems. In the majority of cases, the
lateral open bite is settled during the fixed appliance phase.
Class II functional and orthopedic appliances
Twin block therapy
Twin block (TB) was developed in 1977 (Clark, 2010). Ac-
cording to an RCT by Burhan (Burhan and Nawaya, 2014),
a twin block is recommended for correction of a class II with
mandibular retrusion and to inhibit vertical development.
TB consists of upper and lower removable appliances with
cribs on 64/46’s, ± lower incisor capping, ± torqueing spurs,
±Southend clasp, ± HG attachments, ± labial bow. The in-
clined planes of the blocks are set at approximately 70°.
Bite blocks have approximately 7mm height at the level of
the second premolar which gradually decreases to approxi-
mately around 2mm at the second molar region. Activa-
tions of TB could be transverse using a jackscrew, antero-
posterior, or vertically by addition or removal of acrylic.
Rapid corrections are achieved within 6-9 months (Clark,
3. Hybrid types such as Herbst appliance
Advantages of removable functional appliances
These include:
• Easy to clean
• Less chairside time
• Cheap
• They can transmit forces to blocks of teeth, e.g., arch
expansion.
• They have good vertical and horizontal anchorage
(palatal coverage).
Disadvantages of removable functional appliances
These include:
• Rely on patient cooperation.
• They affect speech, especially in the initial days.
• Lower appliances are particularly difficult to toler-
ate.
• Only tilting movements are possible and thus they
can generate unwanted tooth movements.
Problems with functional appliances
These include:
1. The rebound of overjet: The causes can vary and in-
clude; rebound of condylar position caused by atrophy
of hyper-atrophied meniscus, reduction in the activity of
protractor muscle (lateral pterygoid muscle), uprighting
of the upper labial segment (ULS) or lower labial segment
(LLS). More relapse of the LLS or unfavorable growth.
2. Lower incisor retroclination: tooth-borne appliances,
such as the Herbst appliance, seem to produce greater procli-
nation of lower incisors during growth modification (average
3.2 mm or 11˚) (Hansen et al., 1997). Twin block appliance
cause proclination of lower incisors by 7.9˚ and retroclina-
tion of upper incisors by 10.5˚ (Lund and Sandler, 1998).
Several solutions have been suggested to minimise lower in-
cisor proclination. Studies reported no benefit of lower inci-
sors capping with an average proclination of 5.2+3.9˚ (van
der Plas et al., 2017, Young and Harrisson, 2005). However,
lower incisors capping may affect oral hygiene measures and
induce decalcification of lower incisors (Dixon et al., 2005).
According to a randomized clinical trial, South end clasps on
the lower incisors in a twin block appliance decrease their
proclination (Trenouth and Desmond, 2012). Some sug-
gested grinding the acrylic lingual to lower incisors or even
extending the lower lingual acrylic as posterior as possible.
Brackets with MBT prescription are a useful option due to
the increased negative root torque on lower incisors relative
to the Roth prescription. Alternatively, other functional ap-

80
1982) however the recommended duration of wear of TB
is around 9 to 12 months. According to an RCT by Parekh
(Parekh et al., 2019), the outcome of skeletal and dental ef-
fects of full-time versus part-time wear of a TB was not sta-
tistically significant. According to another RCT (Banks et al.,
2004), there is no difference in incremental advancement in
TB when compared to maximum protusion but may have a
clinical advantage when the full protrusion is not possible.
Twin block design for anterior open bite includes the addition
of occlusal acrylic or wire work, high pull headgear or spinner,
or passive tongue thrush breaker. TB design for the treatment
of Class II div 2 incisors includes the use of bite opening 7mm
or even greater in the start, Z -spring/ELSAA spring or the
use of sectional fixed appliance before or during the TB phase.
TB can be fixed and cemented in situ (Read, 2001).
Advantages associated with the twin block
These include:
• The ease with which it can be worn full-time by a
patient.
• Upper arch expansion can be achieved by incorpo-
rating a midline expansion screw.
• Headgear can be easily attached.
• Fixed appliances can be placed to start the align-
ment of the labial segments.
• TB is robust and relatively easy to fabricate.
• The patient can speak/eat with the appliance on.
Short-term effects of twin block
These include:
• Proclination of lower incisors.
• Retroclination of upper incisors.
• Distal movement of upper molars and/or mesial
movement of lower molars.
• Increase in mandibular length.
• Forward movement of the mandible.
• Restraint of maxillary growth.
Activators appliances
Activator appliances are group of loosely fitting appliances
that come in a single piece or monobloc. It postures the man-
dible forwards by lingual extension of the acrylic monobloc.
Andresen activator was originally described by Viggo An-
dresen. The original Andresen–Häupl activator was worn at
night and had minimal vertical opening. Andresen activa-
tor was based upon the hypothesis of stimulating increased
muscle activity of the mandibular elevator and retractor mus-
cles to act directly on the dentition through the appliance,
and unload the condyle to allow remodeling and growth.
Andresen activator consisted of a loose-fitting monobloc
acrylic body appliance that advanced the mandible with lin-
gual flanges. Facets were cut into the acrylic to guide erup-
tion of the mandibular posterior teeth mesially and the
maxillary posterior teeth distally and buccally. Andresen ac-
tivator has lower incisor capping and an opening of 3-4mm.
Harvold activator (Harvold, 1974) is based on Andresen’s
design and it has an acrylic body with deep lingual flanges.
Acrylic is relieved lingual to the lower incisor. Harvold be-
lieved that the masticatory musculature could not be stimu-
lated during sleep. Therefore, to be effective, the appliance
had to stretch the orofacial connective tissues, including
ligaments and fascial sheets, and direct forces to the teeth
and supporting structures. To achieve this a vertical open-
ing of greater than 10-mm was created on protrusion of the
mandible, which makes the Woodside and Harvold-type ac-
tivators more difficult to tolerate and can affect compliance.
Bionator (Eirew, 1981) is another type of activators and it has
an acrylic body where the acrylic bulk was considerably re-
duced to allow increased wear and normal oral function. It
has a reverse coffin spring to encourage a lower tongue posi-
tion. It contains a reverse loop labial bow which extends about
3-4mmfromteethbuccallytoholdthecheeksawayforpassive
expansion and lower incisor capping with a loose fit overall.
Activators combined with headgear
Functional appliance wear can encourage a clockwise rota-
tional effect on the dentition and dental bases, which can lead
to an increase in the lower face height and greater vertical
rather than a sagittal change in chin position. To minimise
this and optimize skeletal correction in the anteroposterior di-
mension, headgear can be attached to the appliance. The aim
is to restrict the anterior and vertical development of the max-
illa, whilst encouraging forward mandibular growth. Several
activator-type functional appliance systems that incorporate
the use of headgear have been developed. The Tauscher appli-
ance (Teuscher, 1978) has anterior spurs to torque the upper
incisors and prevent their retroclination, allowing the head-
gear appliance to exert a pull as far forward as possible, and
prevent the maxilla from rotating downwards and backward.
The van Beek appliance (van Beek, 1982) is a modified ac-
tivator with headgear directly incorporated into the acrylic,
which patients wear at night and a few hours during the day.
The van Beek appliance is essentially a functional appliance
with an intrusion component.
Bass appliance
The Bass appliance is a maxillary splint to which high-
pull headgear is attached to restrain maxillary growth,
the mandible is guided anteriorly by pads that rest in the
lingual sulcus behind the lower incisors (Bass, 1994).

Medium opening activator
The medium opening activator represents a cutback acti-
vator with cribs to the maxillary first molars and second
premolars to improve retention and make the appliance
more tolerable (Santos et al.). The mandibular protrusion
is achieved via lingual mandibular guidance flanges, with
an anterior hole cut into the acrylic to facilitate breath-
ing and speech. The free eruption of mandibular buc-
cal teeth is encouraged, which allows the reduction of a
deep overbite at the same time as correcting the overjet.
Dynamax appliance
Dynamax appliance is a removable upper appliance with
a fixed lower lingual arch, spurs from the upper interlock
with a lower arch. Dynamax appliance has two compo-
nents. The upper part is removable while the lower could be
removable or fixed as a lingual arch (Bass and Bass, 2003).
A modified fixed upper and lower version is also avaliable
(Bass and Bass, 2003). According to an RCT, twin block is
better than Dynamax for skeletal and soft tissue change
(Lee et al., 2007). According to another RCT by Thiruven-
katachari (Thiruvenkatachari et al., 2010), a twin block
is better than a Dynamax appliance in treating overjet.
Frankel appliance
Frankel appliance is also known as Functional regulator (FR)
and was developed by Rolf Fränkel in what was the German
Democratic Republic. FR has a wire framework with lingual/
buccal shields and lip pads, ± lingual springs for lower inci-
sor, hence, FR has a very fragile design, and it also can be re-
activated (Frankel, 1980). Four types of Fränkel appliances, or
functionalregulators.Thetreatmentphilosophyisbasedupon
full-time wear, but the bulk and fragility of the appliance can
makecompliancedifficult.TherearefourmainsubtypesofFRs:
• FR 1 a for Class I
• FR 1 b for mild Class II/I
• FR 1 c for moderate Class II/I
• FR 2 for Class div II div2
• FR 3 for Class Ill
• FR 4 for Anterior open bite
Fränkel was an advocate of the original functional matrix
theory of growth, which states that there is no direct genetic
influence on the size, shape, or position of the skeletal tissues.
Rather, bony growth is driven by the form and function of the
surrounding soft tissues. Fränkel appliances are designed to
change the muscular and soft tissue environment of the jaws
and therefore modify growth. This is achieved with the use of
wires and acrylic shields to displace the cheeks and lips away
from the teeth, as well as encouraging forward posture of the
mandible. Buccal shields removed pressure by the cheeks to
allow for passive arch expansion, whilst theoretically stretch-
ing the periosteum to produce additional bony apposition
laterally. Lower labial acrylic pads are designed to gently im-
pede the activity of the mentalis muscles thought to be an
aetiological factor of an increased overjet seen in certain pa-
tients. A recent trial showed that both Frankel and modified
twin block are effective with a similar rate of PAR improve-
ment, and patient/ parent perception (Campbell et al., 2020).
Herbst Appliance
Emil Herbst in 1909 Berlin, presented an appliance called
Scharnier or Joint. In 1979 Pancherz (Pancherz, 1979) pre-
sented the possibility of mandibular growth and reintroduced
Herbst appliance along with setting the basis for numerous
appliances to come. Herbst appliance, like twin block, is based
on the principle of jumping the bite, a concept introduced by
Kinglsey in 1880. Bite jumping appliances are recommended
for the treatment of class II mandibular retrusion when the
clockwise rotation of the mandible is desired (Burhan and
Nawaya, 2014). Herbst is a fixed functional appliance with
stainless steel crowns or bands on 6-4/4-6 and 6-4/4-6 con-
tinuous lower lingual bar and a palatal bar connecting 6-4/4-6
/ 6/6, telescopic arms from upper 6/6 to lower 4/4. Protrusion
of the mandible is achieved via the bilateral telescopic appara-
tus attached to maxillary first molar and mandibular first pre-
molar bands. The telescopic arms consist of a tube, plunger,
and pivot, which allows for opening and some lateral excur-
sion, with these arms advancing the mandible so that the inci-
sors are edge to edge. The fixed nature of this appliance means
that effective compliance is not usually an issue, and overjet
reduction in 6 to 8 months is commonly achieved (Pancherz,
1982). However, potential disadvantages are that the Herbst
appliance is expensive to fabricate, is often difficult to toler-
ate, and can be prone to breakage. For activation of the Herbst
appliance, more proclination and protrusion of mandibular
incisors was noticed in the incremental advancement group
when compared to a single advancement (Amuk et al., 2018).
Jasper Jumper appliance
A modified form of the Herbst is a Jasper Jumper (Jasper,
1987), which is a fixed, flexible, non-rigid appliance with a
coil springs and not telescopic arms and used in conjunc-
tion with a fixed orthodontic appliance. Jasper jumper has
mainly mandibular dentoalveolar effects but not skeletal ef-
fects in treating class II malocclusion(de Oliveira et al., 2007).
Jasper Jumper delivers light continuous force to cause the
bite to jump. Transpalatal arch in the maxilla is a must to
restrict expansion components and it is narrowed slightly
with palatal crown torque on the molars and incisors. It is
recommended to use brackets with high lingual crown toque
in mandibular incisors.
MARA (Mandibular anterior repositioning appliance)
The MARA appliance is fixed to the patient’s first molars via

82
a stainless steel crowns. The upper elbows are removable, al-
lowing the clinician to make adjustments. Patients generally
adapt to MARA soon. Upper and lower archwire tubes with
hooks are standard features, allowing the clinician the option
of using fixed mechanics during MARA therapy. A lower lin-
gual arch is also a standard element of the appliance. Other
popular options include an upper transpalatal arch (TPA),
and a variety of palatal expansion screws and habit devices.
An accessory kit of parts is available, which includes advance-
ment spacers, extra elbows, and a torqueing tool to aid in ad-
justing the elbow if required. The smaller size of the appliance
increases comfort and aesthetic appeal for patients. MARA
has both skeletal and dental effects (Ardeshna et al., 2019).
Sabbagh universal spring (SUS):
SUS is a fixed functional appliance with an inner hexagonal
screw to adjust the length and an adjustable spring force. The
dual telescopic design has integrated stops for the inner tele-
scope. The effects are similar to Herbst, headgear, and elastics.
Twin force bite corrector
It is a rigid Herbst type fixed functional appliance. It has dual
cylinders with NiTi springs that exert 200 grams force for 1-2
mm of movement per month. It requires a heavy archwire as
it fits on to the archwire. It is available in double lock and an-
chor wire configurations and is available in 2 sizes. Twin force
bite correctors is used for Class II cases but could be used
for Class III correction by merely reversing the appliance.
Forsus fatigue resistant device (FRD)
FRD is a fixed functional appliance that has a push rod
mechanism and is placed along with a fixed orthodontic ap-
pliance for Class II correction. FRD is placed on the max-
illary molar band headgear tube and the archwire distal to
cuspid or to bicuspid in mandible, which must be at least
0.019”x0.015” stainless steel or above. FRD causes me-
sial force in mandibular arch with intrusive force on inci-
sors; and distal intrusive force on the maxillary arch. FRD
has two module types, which are EZ2 with separate left
and right side and an L- pin module, which is universal.
The appliance has pushrods in 6 different sizes like 22mm,
25mm, 29mm, 32mm, 35m, and 38mm that are directed
for the right and left sides separately. The measurement
scale is used to determine the size of the pushrod to be used
though FRD can be activated with the help of split crimps.
Skeletally anchored Forsus FRD is an effective method for
treating skeletal Class II malocclusion due to the mandibular
retrusion through a combination of skeletal and dentoalveo-
lar changes (Unal et al., 2014). Also, the skeletally anchored
Forsus FRD EZ appliance has less incisor proclination than
Herbst (Celikoglu et al., 2015). For class II treatment mini-
screw anchored FRD Class II correction was mainly dento-
alveolar in both treatment groups. In a comparative study
conventional-Forsus group, a substantial amount of lower
incisor protrusion was observed, whereas retrusion of lower
incisors was found in the Miniplate anchored -Forsus group.
Class III correction appliances
These include:
• Reverse twin block: It can be used as a reverse ap-
pliance for Class III correction. However, if the cor-
rection does happen, it is only due to dentoalveolar
effects and is inferior to the protraction facemask
(Seehra et al., 2011).
• Buccal acrylic lower appliances: To overcome the
problem of limited undercut on the buccal aspect of
lower molars, appliances have been described with
clasp on the lingual aspect of the molars (Bell, 1983).
In this appliance two acrylic baseplates are used,
one on each side resting on the buccal mucosa. The
acrylic is connected across the anterior labial muco-
sa by a stainless-steel bar. A modified Jackson clasp
is used on the lingual aspect, engaging the lingual
undercuts of the molars. The main use of such an ap-
pliance is to retract mesially inclined lower canines
and effective in correction of class III malocclusions.
• Removable mandibular retractor (RMR): RMR is
recommended for Class III patients in the decidu-
ous and mixed dentitions and has been first evalu-
ated by Tollaro (Tollaro et al., 1995) at the University
of Florence in Italy. In this retractor, a labial arch is
extended to the cervical edge of the mandibular inci-
sors and was activated by 2 mm in front of the teeth
when the mandible is forced into maximum retru-
sion. Adams clasps are used for retention, and aux-
iliary devices like expansion screws can also be used
in this appliance. The labial arch in this retraction
acts as a stop to prevent sagittal movement. Accord-
ing to a randomized clinical trial, it is an effective
appliance for Class III treatment (Saleh et al., 2013).
Factors affecting the choice of functional appliances
a. Patient-related factors such as:
• Age
• Compliance
• Oral Hygiene
• Malocclusion type
• Preference
b. Clinician factors such as:
• Preference/familiarity
• laboratory facilities
• Available evidence

Recommended wear time of removable functional appli-
ances
Mostly 12-14 hours of part-time wear is required for Andre-
sen, Harvold, and Bionator, while full-time wear is required
for twin block, Herbst, Frankel (except for eating/sports).
According to a recent RCT by Parekh (Parekh et al., 2019),
part-time (12 hours) and full-time (22 hours) wear of twin
block had similar dental and skeletal effects over 12 months.
Statistically significant differences were seen based on sex,
age, location, and health insurance. Wear time decreased as
age increased, with the youngest patients wearing their appli-
ances for a median of 12.1 hours per day, and the oldest wear-
ing them for 8.5 hours a day. Girls wore their devices longer
in each age group by 1.3 hours. Headgear appliances both for
skeletal class II or III correction are used for 12 to 14 hours.
Timing of intervention using functional appliance therapy
Usually, cervical vertebra maturation stages are used to ac-
cess the optimum timing of growth modification. For Class
III growth modification CVM stage 2 is advocated to be
the best indicator for the start of treatment while for skel-
etal Class II growth modification CVM stage 3 or 4 are re-
ported to be ideal. However, a systematic review has shown
that the studies on the CVM method for radiographic as-
sessment of skeletal maturation stages suffer from serious
methodological failures (Santiago et al., 2012). For class II
growth modification, optimum use of the functional appli-
ance is during pubertal growth spurt (DiBiase et al., 2015).
When functional appliance treatment for Class II maloc-
clusion is commenced during the growth spurt or just af-
ter initiation of spurt it produces more favorable skeletal
changes, mandibular length and ramus height increase, and
condylar growth as compared to treatment initiated before
peak height velocity (Baccetti et al., 2000). But the predic-
tion of the growth spurt is difficult, with 33% of predictions
more than 1 year away from actual growth spurt occuring.
According to Hoffmann (Hoffmann et al., 2013), boys and
girls mostly undergo orthodontic treatment at the same age.
Given the delayed onset of puberty in boys, most are still
pre-pubertal, whereas most girls have reached an advanced
stage of puberty by the time they undergo treatment, a dis-
crepancy that could have therapeutic implications. Accord-
ing to systematic review and meta-analysis (Perinetti et al.,
2014), fixed functional appliances are effective in the treat-
ment of Class II with skeletal effects during the pubertal
growth spurt. Overall supplementary total mandibular elon-
gations as mean were 1.95 mm and 2.22 mm among puber-
tal patients and -1.73 mm and 0.44 mm among postpuber-
tal patients, for functional and comprehensive treatments.
According to an RCT (Ghafari et al., 1998), with headgear
or functional regulator, treatment in late childhood was as
effective as that in mid-childhood. This finding suggests that
the timing of treatment in developing malocclusions may be
optimal in the late mixed dentition, thus avoiding a reten-
tion phase before a later stage of orthodontic treatment with
fixed appliances. (Ghafari et al., 1998).
The duration of functional treatment is usually 6-12 months,
but according to an RCT (Banks et al., 2004), the duration of
treatment was influenced by the operator and initial overjet.
Success rates of functional appliances
• For successful growth modification, the patient
should be compliant with treatment. According to
an RCT (Tulloch et al., 1998), compliance seems to
explain little of the variation in treatment response.
Non-compliance is defined as those patients who
refuse treatment despite all efforts to engage them
(Ghafari et al., 1998). Starting treatment earlier than
12.3yrs significantly improves cooperation by 3
times (Banks et al., 2004).
In summary, the success rate of:
• Fixed TB failure is 3% (Read, 2001)
• Twin block failure range from 9% (Harradine and
Gale, 2000) to 14% (Morris et al., 1998, Gill and
Lee, 2005) and up to 33.6%.
• Dynamax appliance ranges from 9% (Lee et al., 2007)
to 28% (Thiruvenkatachari et al., 2010).
• Herbst appliance is 12.9%
• In a randomized comparison (Ghafari et al., 1998)
of early treatment, HG and Frankel of Cl 11/1: 42%
of females and 24% of males uncooperative with
Frankel appliance.
therapy
The scientific evidence concerning the stability of treatment
results is inexistent for most fixed functional appliances for
Class II correction except for Herbst appliance treatment
(Bock et al., 2015, Wieslander, 1993). Approximately 2 years
after Herbst treatment, the Herbst subjects with different
vertical facial patterns showed similar patterns of skeletal
change compared with the Class II controls treated with
elastics (Atresh et al., 2018).
It has been shown that maxillary changes are more stable
than mandibular changes (Pancherz, 1991) and most relapse
is due to dentoalveolar changes, 58% dental relapse and 42%
skeletal relapse (Pancherz and Fackel, 1990). A good buccal
interdigitation decreases dental relapse. If early treatment is
done with a functional appliance, then consider the reten-
tion of skeletal and dental relationship (Wiltshire and Tsang,
2006).
Early versus late treatment
1. Early treatment and traumatic dental injuries (TDI): A

84
EXAM NIGHT REVIEW
Definition
Removable or Fixed orthodontic appliances use forces
generated by the stretching of muscles, fascia, and periodon-
tium to alter skeletal and dental relationships (Mills, 1991).
History of Functional Appliances
• Monobloc (Robin, 1902).
• Andreasen’s appliance Andreasen and Haupl in1936
• Bionator by Wilhelm Balter in1950.
• Frankel appliances (Frankel, 1966).
• Clark’s twin (Clark, 2010).
Theories on how functional appliances work
1. Facial soft tissues
2. Muscles of mastication.
3. Dentition
large fraction (21.8%) of TDIs attributable to a large overjet.
This high global burden of TDI suggests that preventive
measures must be implemented in patients with a large
overjet. According to a meta-analysis (Petti, 2014), in young
persons with overjet greater than 3-4mm, the chance of
trauma increases by a factor of 2. Treatment with functional
appliances may not decrease the incidence of trauma in
those who have already experienced upper incisor trauma
(Koroluk et al., 2003). According to a Cochrane review (Ba-
tista et al., 2018), there is some decrease in the incidence of
trauma with early treatment.
2. Early treatment and psychosocial benefits: According
to a systematic review (Dimberg et al., 2014), malocclusions
have negative effects on OHRQOL in children and pre-ado-
lescents, predominantly in the dimensions of emotional and
social wellbeing. Early treatment with TB increases self-es-
teem, self-concept, and reduced negative social experiences
(O’Brien et al., 2003b, O’Brien et al., 2003a, O’Brien, 2006).
Early treatment is generally not justified unless the patient is
being bullied and would benefit psychologically as the cost
of early treatment in terms of attendance and length of treat-
ment is increased (O’Brien et al., 2009b).
Use of functionals in the UK
Functional appliances are common in the UK, as per a
national survery (Chadwick et al., 1998) 99% of orthodon-
tists use functionals to treat Class 11/1, 63% of orthodontists
use functionals to treat Class 11/2, 16% of orthodontists use
functionals to treat Class Ill. Finally, Clark TB was the most
popular (75% of functional appliances)
4. Jaws skeleton
Functional appliances and airway
• An increase in the upper airway volume was found
after treatment with functional appliances(Isidor et
al., 2018).
Skeletal modification by functional appliances
Jaw position and size
• According to a systematic review (Niu and Zhou,
2011), a functional appliance can enhance mandibu-
lar growth in the treatment of skeletal Class II mal-
occlusion. This mainly due to the growth of the ra-
mus instead of changes in mandibular body length.
Growth direction
• Principally it occurs in the vertical direction (Mills,
1991).
• According to a systematic review (Nucera et al.,
2016), removable functional appliances in Class II
growing patients have a slight inhibitory effect on
the sagittal growth of the maxilla in the short term,
but they do not seem to affect the rotation of the
maxillary plane.
4. Position of glenoid fossa post appliance treatment
• According to a systematic review (Al-Saleh et al.,
2015), there is inconclusive evidence on TMJ change
in the use of fixed functional appliances.
• The twin block is more effective in relieving joint
pain, diminishing joint dysfunction, reducing joint
clicking, and eliminating muscle tenderness in pa-
tients with anterior disc displacement with reduc-
tion as compared to the occlusal splint (Rohida and
Bhad, 2010).
Summary of evidence for the effect of appliances
• The effects of class II functional appliances are most-
ly dental and with small skeletal growth modifica-
tion. Skeletal effects of Class II growth modification
are restraining of maxillary growth and favorable
mandibular growth while the dentoalveolar effects
are tipping of teeth. 70% of overjet decrease is due to
tipping in Class II cases (Pancherz, 1984).
• The skeletal effects are mostly statistically significant
but clinically insignificant.
• According to a Cochrane review by Batista (Batista
et al., 2018), there is low-quality evidence for ANB
correction with twin block is better than another
appliances. Removable functional appliances were
more effective in terms of ANB difference than fixed
functional appliances.

Soft tissue effects of the functional appliance
• According to a systematic review (Ren, 2007), func-
tional appliances, produced statistically significant
soft tissue effects, but their clinical significance is
questionable.
Profile silhouettes of children who had received early orth-
odontic treatment for Class II malocclusion using twin block
were perceived to be more attractive by peers than those of
children who did not receive treatment.
Indications of a functional appliance
• Growing patients
• Well-motivated patients
• Uncrowded, well-aligned class II division1 on mild/
moderate skeletal II base with no subsequent need
for the fixed appliance (Cozza et al., 2006).
• Interceptive appliance for increased overjet in mixed
dentition
• Anchorage
• To correct facial asymmetry using a hybrid appli-
ance
• Habit breaker appliance for example digit sucking.
Relative contra-indications/ not suitable for appliance
• Non-growing patients
• High-angle cases with backward mandibular growth
rotation, but can also be used with a careful design
(Ruf and Pancherz, 1998).
• In anterior open bite cases with proclined lower in-
cisors, further proclination is minimized with inci-
sor capping (Trenouth, 2000).
• Cases with retroclined upper incisors
• Cases with crowding that can be treated with fixed
appliances and extractions.
Classification of functional appliances
• Myotonic e.g. Harvold activator - large mandibular
opening (8-10mm), work by passive muscle stretch.
• Myodynamic e.g. Andresen activator - medium
mandibular opening (<5mm), work by stimulating
muscle activity
According to the mode of retention (Houston et al., 1992)
• Passive tooth-borne e.g. Andresen
• Active tooth-borne e.g. Twin block
• Tissue borne e.g. Frankel
• Component approach e.g. hybrid appliance Vig (Vig
and Vig, 1986)
• Fixed functional e.g. Herbst (Pancherz, 1979).
3. Check the activation of the active components(if pres-
ent) of the appliance
Advantages of removable functional appliance
• Clean
• Less chairside time
• Cheap
• They can transmit forces to blocks of teeth, e.g., arch
expansion.
• They have good vertical and horizontal anchorage
(palatal coverage).
Disadvantages of removable functional appliance
• Rely on patient cooperation.
• They affect speech, especially in the initial days.
• Lower appliances are particularly difficult to toler-
ate.
• Lab work is required.
• Only tilting movements are possible and thus can
generate unwanted tooth movements,.
Solutions to prevent the increase in lower incisor inclina-
tion:
• Acrylic capping of lower incisors
• Southern end clasps
• Relief to the acrylic lingual to lower incisors
• Extending the lower lingual acrylic as posterior as
possible
• Short time use or avoidance of class 2 elastic
• MBT prescription
• Headgear with a functional appliance
• Favorable skeletal outcomes can be achieved by skel-
etal anchorage therapies
Upper incisor retroclination:
• RCT by Trenouth (Trenouth and Desmond, 2012)
advocated the use of South end clasps to prevent in-
cisor retroclination.
Class II functional and orthopedic appliances
Twin block therapy
• Developed 1977 (Clark, 2010)
• It consists of upper and lower removable appli-
ances with cribs on 64/46’s, ± lower incisor capping,

86
Activators
• Activators form a group of loosely fitting appliances
that come in a single piece or monobloc.
• It postures the mandible forwards by lingual exten-
sion of the acrylic monobloc.
Andresen activator
• It consisted of a loose-fitting monobloc acrylic body
appliance that advanced the mandible with lingual
flanges.
• Facets were cut into the acrylic to guide eruption
of the mandibular posterior teeth mesially and the
maxillary posterior teeth distally and buccally.
Harvold Activator.
• It has an acrylic body with deep lingual flanges.
Acrylic is relieved lingual to lower incisor.
• The opening is increased 8-10m, and rapid correc-
tion is achieved. Believed that the masticatory mus-
culature could not be stimulated during sleep.
• more difficult to tolerate.
Bionator
• Bionator (Eirew, 1981) has an acrylic body of which,
the acrylic bulk was considerably reduced to allow
increased wear and normal oral function
• It has a reverse coffin spring
Activators combined with headgear
• The Tauscher appliance (Teuscher, 1978) has ante-
rior spurs to torque the upper incisors and prevent
their retroclination
Bass appliance
• The Bass appliance is essentially a maxillary splint to
which high-pull headgear is run to restrain maxil-
lary growth
Medium opening activator (Santos et al.)
Cribs to the maxillary first molars and second premolars to
improve retention and make the appliance more tolerable.
• The mandibular protrusion is achieved via lingual
mandibular guidance flanges, with an anterior hole
cut into the acrylic to facilitate breathing and speech.
Dynamax appliance
• It is a removable upper appliance with a fixed lower
lingual arch, spurs from the upper interlock with a
lower arch.
• Dynamax appliance has two components. The up-
per part is removable while the lower could be re-
± torqueing spurs, ±Southend clasp, ± HG attach-
ments, ± labial bow.
• Inclined planes 70°.
• Bite blocks 7mm
• Activations could be transverse with a jackscrew,
anteroposterior, or vertically by addition or removal
of acrylic, respectively.
• The recommended duration of wear is approxi-
mately 9 to 12 months.
Advantages associated with the twin block
• The ease with which it can be worn full-time by pa-
tients.
• Upper arch expansion can be achieved by incorpo-
rating a midline expansion screw
• Headgear can be easily attached
• Fixed appliances can be placed to start alignment of
the labial segments
• This appliance is robust and relatively easy to fabri-
cate.
• The patient can speak with the appliance on.
• The patient can eat with the appliance.
• Comparatively more esthetic without a labial bow
Short term effects of twin block include:
• Proclination of lower incisors:
• Retroclination of upper incisors
• Distal movement of upper molars and/or mesial
movement of lower molars
• Increase in mandibular length
• Forward movement of the mandible
• Restraint of maxillary growth was not found
Twin block design for anterior open bite
• Add occlusal acrylic or wire work
• High pull headgear
• Spinner or passive tongue thrush breaker
Twin block for Class II div 2 incisors
• Make bite opening 7mm or even greater in start
• Add Z -spring
• Add sectional fixed appliance before or during TB
treatment
• Add ELSAA spring

movable or fixed as a lingual arch(Bass and Bass,
2003).
Frankel appliance
• Also known as Functional regulator (FR)
• The treatment philosophy is based upon full-time
wear, but the bulk and fragility of the appliance can
make compliance difficult.
Types:
• FR 1 a for Class I
• FR 1 b for mild Class II/I
• FR 1 c for moderate Class II/I
• FR 2 for Class div II div2
• FR 3 for Class Ill
• FR 4 for Anterior open bite
Fränkel was an advocate of the functional matrix theory of
growth
Herbst Appliance
• Herbst is a fixed functional appliance with stainless
steel crowns or bands on 6-4/4-6 and 6-4/4-6 con-
tinuous lower lingual bar and a palatal bar connect-
ing 6-4/4-6 / 6/6, telescopic arms from upper 6/6 to
lower 4/4.
• Protrusion of the mandible is achieved via a bilateral
telescope apparatus attached to maxillary first molar
and mandibular first premolar bands
Jasper Jumper appliance
• A modified form of Herbst is Jasper Jumper (Jasper,
1987), which is a fixed, flexible, non-rigid appliance
having coil springs and telescopic arms and used in
conjunction with a fixed orthodontic appliance.
MARA (Mandibular anterior repositioning appliance)
• MARA appliance is fixed to the patient’s first molars
with stainless steel crowns. The upper “elbows” are
removable, allowing the clinician to make adjust-
ments. Patients generally adapt to MARA soon.
Twin force bite corrector
• Rigid Herbst type fixed functional appliance. It
has dual cylinders with NiTi springs that exert 200
grams force for 1-2 mm of movement per month.
Forsus fatigue resistant device:
It is placed on the maxillary molar band headgear tube and
the archwire distal to cuspid or to bicuspid in mandible,
which must be at least 0.019”x0.025” stainless steel or above.
It causes mesial force in a mandibular arch along with intru-
sive force on incisors; and distal along with intrusive force
on the maxillary arch.
Class III correction appliances
Reverse twin bloc for Class III correction.
Removable mandibular retractor (RMR)
• RMR is recommended for Class III patients in the
deciduous and mixed dentitions.
• A labial arch is extended to the cervical edge of the
mandibular incisors
Factors affecting the choice of functional appliances
Patient-related factors
• Age
• Compliance
• Oral Hygiene
• Malocclusion type
• Preference
Clinician factors
• Preference/familiarity
• laboratory facilities
• Available evidence
Success rates of functional appliances
• Fixed TB failure 3% (Read, 2001)
Twin block failure range from 9% (Harradine and Gale,
2000) to 14% (Morris et al., 1998, Gill and Lee, 2005) and up
to 33.6%, RCT (O’Brien,2003)
• Dynamax 9% (Lee et al., 2007) to 28% (Thiruven-
katachari et al., 2010).
• Herbst 12.9% (O’Brien,2003)
therapy
Maxillary changes are more stable than mandibular changes
Most relapse is due to dentoalveolar changes
Good buccal interdigitation
Early versus late Treatment
3. Early treatment and traumatic dental injuries (TDI)
• According to a meta-analysis (Petti, 2014), in young
persons with overjet greater than 3-4mm, the chance
of trauma increases by a factor of 2 on them.
• According to a Cochrane review (Batista et al.,
2018), there is some decrease in the incidence of
trauma with early treatment.

88
4. Early treatment and psychosocial benefits
• • Early treatment with TB increases self-esteem, self-
concept, and reduced negative social experiences
(O’Brien et al., 2003b, O’Brien et al., 2003a, O’Brien,
2006).
Research problems
• Small samples (Tulloch et al., 1990) with poor or no
controls
• Different appliances compared
• Different interpretations
• Inaccuracies in measurement
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