Selection of dental implant patients/ prosthodontic courses

Selection of patient for intraoral
implants
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

Introduction
The use of dental implants to provide support for replacement of
missing teeth is becoming an important component of modern
dentistry. As a result of advances in research on implant design,
materials, and techniques the use of these devices has increased
dramatically in the past few years and is expected to expand further
in the future. Many types of implants are now available for
application to different clinical cases, and an increasing number of
dentists have become involved in this form of treatment.
Many individuals with edentulism can be treated with partial or
complete traditional removable dentures or fixed bridges. However,
these prostheses are not satisfactory for a significant number of
individuals who have lost the tooth-bearing portions of the bone and
simply cannot manage removable prostheses, or are medically
compromised and cannot properly masticate food. Moreover, there is
a strong suggestion that a substantial number of patients prefer
implant- supported prostheses over soft tissue supported prostheses.

Research advances in dental implantology have led to
the development of several different types of implants, and it is
anticipated that continued research will lead to improved
devices. At present, continued evaluation is necessary to
determine that appropriate implant devices are available to
meet the therapeutic demands of the different portions of the
jawbones and the unique needs of patients.
Criteria of success vary with different implant systems.
Therefore, it is difficult to compare certain types of implants for
which success criteria and indications may be different.
Dental implants may be classified by type as endosseous,
subperiosteal, transosteal, intramucosal, endodontic, and bone
substitutes

These implant types are subdivided as follows:
• Endosseous:
Root form.
Blade (plate) form.
Ramus frame.
• Subperiosteal:
Complete.
Unilateral.
Circumferential.
• Transosteal:
Staple.
Single pin.
Multiple pin.www.indiandentalacademy.com

For long-term successful performance of all dental
implant types the following general factors should be
considered:
•Biomaterials.
•Biomechanics.
•Dental evaluation.
•Medical evaluation.
•Surgical requirements.
•Healing processes.
•Prosthodontics.
•Postinsertion maintenance.

All practitioners involved in patient care should be knowledgeable
regarding these factors and their interrelationships. Standards of
dental practice would suggest the following general
contraindications for the above three categories of dental implants:
• Debilitating or uncontrolled disease.
• Pregnancy.
• Lack of adequate training of practitioner.
• Conditions, diseases, or treatment that severely compromise
healing, e.g., including radiation therapy.
• Poor patient motivation.
• Psychiatric disorders that interfere with patient understanding and
compliance with necessary procedures. Unrealistic patient
expectations.
• Unattainable prosthodontic reconstruction.
• Inability of patient to manage oral hygiene.
• Patient hypersensitivity to specific components of the implant.www.indiandentalacademy.com

With regard to indications for a specific implant type, the bone
available to support the implant is the primary factor after
prosthodontic diagnosis and treatment plan. This bone is
measured in width, height, length, anatomical contour, and
density. These physiological and anatomical factors may be altered
by either osteoplasty or augmentation of the bone. In addition,
other factors affecting indications for implant type are the degree
and location of the edentulism of the patient.

Indications for each implant type are specified below:
• ENDOSSEOUS, root form:
o Adequate bone to support the implant with width and height
being the primary dimensions of concern.
o Maxillary and mandibular arch locations.
o Completely or partially edentulous patients.
• ENDOSSEOUS, blade (plate) form:
o Adequate bone to support the implant with width and length
being the primary dimensions of concern.
o Maxillary and mandibular arch locations.
o Completely or partially edentulous patients.

• ENDOSSEOUS, ramus frame:
oAdequate anterior bone to support the implant with width
and height being the primary dimensions of concern.
oMandibular arch location.
oCompletely edentulous patients.
• SUBPERIOSTEAL, complete, unilateral, circumferential:
oAtrophy of bone but with adequate bone to support the
implant.
oMaxillary and mandibular arch locations.
oCompletely and partially edentulous patients.
oStable bone for support.

• TRANSOSTEAL, staple, single pin, multiple pin:
ο Adequate anterior bone to support the implant.
o Lack of adequate training of practitioner.
ο Conditions, diseases, or treatment that severely
compromise healing, e.g., including radiation therapy.
ο Poor patient motivation.
ο Psychiatric disorders that interfere with patient
understanding and compliance with necessary
procedures.
ο Unrealistic patient expectations.
ο Unattainable prosthodontic reconstruction.
ο Inability of patient to manage oral hygiene.
o Patient hypersensitivity to specific components of the
implant.

Implant treatment is delivered in several ways:
(1) By multidisciplinary teams of dentists in which an oral
surgeon or periodontist performs the surgical component of the
implant and a prosthodontist performs the prosthetic component;
(2) By individual implantologists with extensive training in
both the surgical and prosthetic components who perform all
aspects of the procedure;
Patient selection should be restricted to those patients who
show a need and motivation for the implant procedures. The
evaluation of the recipient should include a survey of adequate bone
structure, medical history, and, where indicated, medical laboratory
studies and consultation with the patient's physician. The use of
computerized tomography for evaluation of maxillary and
mandibular anatomy is suggested when more accurate information
regarding implant placement is needed. The patient's dental
evaluation also should include a psychosocial appraisal of his or her
suitability for implant procedures when psychological symptoms
are present. www.indiandentalacademy.com

Osseointegration is the
direct structural and
functional connection
between ordered, living
bone, and surface of a load
carrying implant

Baseline vital signs of
blood pressure. Pulse
and temperature
should be taken in the
evaluation stage

The sequential multiple
analyzer allows for
analysis of specific blood
components, which may
be helpful in diagnosing
underlying systemic
diseases

Complete blood
count is determined
in the clinical
laboratory

Urine analysis
should precede
Stage I surgery

Chest X-rays are
taken if general
anaesthesia is being
considered.

Baseline E.C.G
should be
completed pre-
operatively

A thorough clinical
assessment should
be undertaken for
every patient
before undergoing
therapy

Assessment
of any oral
pathology

Assessment
of TMJ
function

In partially edentulous
patients an evaluation
of pocket depth should
be made with a
Michigan O Probe with
Williams markings

Use of disclosing
agents facilitates
assessment of the
plaque index

Presence of
calculus should be
noted

Mobility patterns
may be ascertained
by using a mirror
handle and a
periodontal probe
handle placed at
opposite ends of
the tooth.

The patients past
personal oral
hygeine habits and
periodontal health
may be accurate
predictors of
his/her projected
compliance in the
maintenance of
osseointegrated
implants.

Intra oral and extra
oral photographs
should be taken pre-
operatively, intra-
operatively and post
operatively

Diagnostic study
models are helpful in
treatment planning
an projecting goals to
the patient pre-
operatively. They
also aid in this
retrospective analysis
of the progress of
therapy.

Pre-operative
radiographic analysis
is one of the most
critical aspects of the
clinical evaluation

Diagnostic wax
up aids in the
proper projection
of functional and
aesthetic goals

In planning the
implant case we
must think is
reverse, i.e., we
need to plan the
final outcome
prior to the
placement of
fixtures.

Diagnositc wax up
may then be
duplicated and
appropriate surgical
stents created.

The facebow fork with
wax, compound or any
other accurate
recording medium is
placed in the mouth
and pressed against the
maxillary arch. The
facebow is centered on
the face and then held
in position and
tightened.

A centric relation
record is started by
pressing wax against
the maxillary teeth.
The mandible is
manipulated into
centric relation
position and guided
into the wax.

Wax record is then
trimmed through
the buccal cusp tip
of the maxillary
teeth. The wax
record is tried
back in the mouth
to verify its
accuracy.

Wax record is floated
in room temperature
water to prevent
distortion

The mounts are
poured, trimmed
and mounted in
the conventional
manner.

situations, a complete
radiographic survey
should be done

Partially edentulous
situation, the
panoramic radiograph
can be of value in
radiographic
assessment of gross
osseous pathology,
appropriate tooth
position and some
indication as to
appropriate fixture site
location and length.

The appropriate
location of
neurovascular
bundle and fixture
site locations may
be projected.

The lateral
cephalometric
radiograph is of
much greater
diagnostic value
for the fully
edentulous
patient.

A tomogram is
used to evaluate
the patients bony
topography

Section of tomogram
used to evaluate the
bony topography in
the posterior maxilla

Computerized
tomography is an
important part of
the pre-operative
radiological
analysis.

Treatment sequence – Edentulous
•Diagnostic records
•Transitional prosthesis
•Surgery / fixture placement
•Surgery / abutment connection
•Definitive restoration
•Maintenance

situation a diagnostic
wax up has been
completed utilizing
denture teeth.

Metallic balls
have been
incorporated into
the stent to allow
for calculation of
the magnification
error

Radiological stents
prepared for CT
scans should be
prepared with gutta
percha radiographic
markers rather than
with stainless steel
balls to prevent
scatter.

Biomechanical considerations
The purpose of inserting implants into the jaw bone is to
establish long lasting support for the patients prosthetic teeth.
From a mechanical point of view is it thus essential to
consider the strength of the elements involved and load
supplied in order to establish the desired long term function.
When placing the fixtures in the bone the surgeon
establishes the base for the future function of the implant
supported prosthesis. The number and positions of the fixture
and anchorage quality are defined at the time the surgical
procedure is carried out. An understanding of basic
biomechanical relationships is therefore essential for the
surgeon striving for long term success for the patient.

The following guidelines are valuable for minimizing the risk
of overload as well as minimizing its possible consequences:
1. The lever arm principle is affective for estimating the
distribution of forces between implants as well as on each
individual implant.
2. The force direction to strive for is axial on the fixtures.
3. The key factor for achieving axial load is spreading the
implant in both mesial / distal and buccal / lingual directions.
4. Fixtures along the straight line such as two fixture solutions
may provide critical problems. Placements of at least one
offset fixture is crucial in such cases.
5. Preservation of as much high quality cortical bone as possible
at the coronal neck is essential for optimizing the
biomechanical strength of the system
6. Bi-cortical anchorage of the fixture is advantageous for
minimizing the stress level of the bone.www.indiandentalacademy.com

In the full arch prosthesis, the implants constitute bridge
posts which share the applied prosthetic loads as axial forces
between them. Placing the implants evenly along an arch enables
this axial load distribution. In partial prosthesis with shorter span,
this geometrical implant spread is not always possible. In such
cases it is appropriate to look at the fixture as being an artificial
tooth root rather than a bridge post, because it may have to
withstand load in all direction from the connected prosthesis.
Implant supported partial prosthesis are therefore more sensitive
to the precise and detailed placement and anchorage of the fixtures
than are full arch prosthesis.

SINGLE FREE STANDING FIXTURE
The single tooth replacement in the anterior part of the jaw
means the replacement of a missing natural tooth with a fixture
of approximately the same dimensions as the missing natural
tooth. If the fixture in such a case is as long as the missing
natural root and has the same bone support as the natural root
once did, sufficient bone strength can be expected. Thus the
load limits will not be defined by the bone in such a situation.
In the posterior part of the jaw, however, a single fixture
does not correspond to the lost root support of a molar which
ordinarily has multiple roots of approximately the same
dimensions as a fixture. Extension of the prosthetic tooth
beyond the outer diameter of the abutment introduces
cantilever affects and fixture bending movement. Considering
these factors in combination with the fact that loading factors
are at their greatest in the posterior region of the mouth, it is
easy to understand that a single fixture in the molar region may
be subjected to excessive forces.

TWO FIXTURES
Two fixtures supporting the prosthesis will always define a line
connecting the surface of the implant and around which the prosthesis load
can cause a bending movement. Such a movement will occur if a vertical load
is applied offset to this center line. Also a transverse force component will
always be derived from occlusal contact force as a result of the inclination of
the cusps. The transverse force will lead to a bending of the implant as well. If
prosthesis has an extension the leverage will enhance any transverse force
applied at the end of the extension.
Thus the two fixture solution makes bending movements on the
implants all but inevitable and substantial stress magnification can be
developed due to lever arm affects in some situations. In corresponding
positions, natural teeth are always supported by multiple tooth roots, spread
along the extension of the teeth. Unfortunately, the two fixture solution is
incapable of giving such optimal support leading to high stress levels. Ins as
much as this situation often occurs in the posterior part of the mouth where
the occlusal forces are at their greatest, both proper support of the fixture
threads in cortical bone and bi-cortical anchorage are essential to assure
sufficient bone strength at the implant site. Bi-cortical anchorage may
sometimes be achieved by buccally/lingually placed fixtures.

THREE OR MORE FIXTURES
To eliminate the risk of excessive bending at a partial
implant supported prosthesis the placement of a third fixture is
recommended. This third fixture makes it possible to spread the
fixture support analogously. If three fixtures are anatomically
possible they should be placed slightly out of line with an offset of
a minimum of 2-3 mm. By doing so the prosthesis will be
supported by a tripod and any offset axial force or any transverse
force will be counter acted by axial forces on the fixtures. The
placement of third offset fixture brings the situation back to the
preferred vertical load distribution among the bridge posts
supporting the prosthesis.

OVERDENTURE
Transverse forces and bending movement
The purpose of supporting an overdenture by implants is
to retain the prosthesis and to stabilize its position. The
stabilizing function means that transverse forces from biting or
chewing will act in the posterior/anterior direction at the
attachment level. Thus in the case of only two fixtures supporting
the overdenture, the fixtures will be subjected to bending
movements. If a third fixture is possible, and placed offset to the
other two, it is possible to compensate for this transverse force by
axial forces as in the partial cases. To benefit from this third
fixture the implants have to be connected to each other by a bar
or bridge.

Load magnitude and bone quality
Transverse forces in the case of an overdenture maybe
of a large magnitude since the implants have to withstand the
total transverse force applied to the prosthesis. Therefore, the
anchorage of the fixtures in the bone is crucial in this form of
treatment and long fixtures and short abutments are
preferred. In weak bone the third fixture and a bar
construction should be utilized in order to minimize the
loading of the bone. The implant supported overdenture
represents a therapy with potential high loads and should be
carefully planned in situations with weak bone such as in the
maxilla.

In completely edentulous patients a removable implant supported
prosthesis offers several advantages over a fixed restoration:
1. Fewer implants are required
2. Prosthodontic appointments are shorter, components costs are
decreased, prosthesis are less complicated and treatment is less
expensive for the patient as a consequence.
3. Long term professional maintenance or treatment of
complications is facilitated.
4. Daily home care is easier.
5. Patient aesthetics can be enhanced with labial flanges and denture
teeth compared with customized metal or porcelain teeth. The
labial contours can replace lost bone width and height and
support the labial soft tissues without hygienic compromise.
6. The prosthesis can be removed at night to manage parafunction.

The patient should not be encouraged to accept a fixed
prosthesis if a removable prosthesis can adequately satisfy the
patients needs and desires. Ideally the fixed partial denture is
completely implant supported rather than joining implants to teeth
. This concept leads to the use of more implants in the treatment
plan. Although this may be a cost disadvantage, there are
significant advantages. The added implants in the edentulous site
result in fewer pontics, more retentive units in the restoration, and
less stress to the supporting bone. As a result, complications are
minimized and implant and prosthesis longevity are increased.
The final restoration must be visualized at the onset. After
this first importance to, the individual areas of abutment support
are determined. If natural teeth are present in those areas, they
are evaluated using the criteria of traditional prosthodontics. If no
natural teeth are in the areas of primary support, the bone is
evaluated to assess which type of implant may be placed to support
the intended prosthesis. www.indiandentalacademy.com

BONE DENSITY
Available bone is particularly important in implant dentistry and
is describes the external architecture or volume of the edentulous
areas considered for implants. In addition, bone has an internal
structure described in terms of quality or density which reflects
the strength of the bone.
Following the standard surgical and prosthodontic protocol,
Adell et al reported an approximate 10% greater success in the
anterior mandible as compared to the anterior maxilla. Lower
success rates were also noted in the posterior mandible as
compared to the anterior mandible with the same protocol was
followed by Schnitman et al. The highest clinical failure rates have
been noted in the posterior maxilla.

BONE CLASSIFICATION SYSTEMS RELATED TO
IMPLANT DENTISTRY
Linkow in 1970, classified bone density into three
categories:
Class I bone structure: this ideal bone type consists of evenly
spaced trabeculae with small cancellated spaces.
Class II bone structure: the bone has slightly larges cancellated
spaces with less uniformity of the osseous pattern.
Class III bone structure: large marrow filled spaces exist
between bone trabeculae.

Lakholm and Zarb, in 1985, listed four bone qualities found in
anterior regions of the jaw bone.
Quality 1: composed of homogenous compact bone.
Quality 2: thick layer of compact bone surrounding a core of
dense trabecular bone.
Quality 3: thin layer of cortical bone surrounding dense
trabecular bone of favourable strength.
Quality 4: thin layer of cortical bone surrounding a core of low
density trabecular bone.

Misch bone density classification (1988)
D1: Dense cortical bone
D2: Thick dense to porous cortical bone on crest and course
trabecular bone within.
D3: Thin porous cortical bone on crest and fine trabecular
bone within.
D4: Fine trabecular bone
D5: Immature, non-mineralized bone.
In order to communicate more broadly to the profession
related to the tactile sense of different bone densities this
classification is compared to materials of varying densities.

Drilling and placing implants into D1 bone is similar to drilling
and into Oak or Maple wood.
D2 bone is similar to the tactile sensation of drilling into white
pine or Spruce.
D3 bone is similar to drilling into Balsa wood.
D4 bone is similar to drilling into Styrofoam.

RADIOGRAPHIC BONE DENSITY
Periapical or panoramic radiographs are not very beneficial to
determine bone density because the lateral cortical plates often obscure
the trabecular bone density.
Bone density may be more precisely determined by tomographic
radiographs, especially computerized tomograms. Ct produces axial
images of the patients anatomy perpendicular to the long axis of the
body. Each CT axial image has 260,000 pixels and each pixel has a CT
number (Hounsfield unit) related to the density of the tissues within the
pixel. In general the higher the CT number, denser the tissue.
D1: More than 1250 Hounsfield unit
D2: 850 –1250 Hounsfield unit
D3: 350-850 Hounsfield unit
D4: 150-350 Hounsfield unit
D5: less than 150 Hounsfield unit

CROWN IMPLANT BODY RATIO
The crown implant body ratio impacts the appearance of
the final prosthesis and the amount of movement of force on the
implant and surrounding crestal bone. The crown height is
measured from the occlusal or incisal plane to the crest of the
ridge and the endosteal implant height from the crest of the ridge
to its apex. The greater the crown height the greater the
movement force of lever arm to lateral force. Aesthetically, the
prosthesis is likely to replace the sole anatomic crowns of natural
teeth when a greater crown implant ratio is present. As the crown
implant ratio increases the number of implants and / or wider
implants should be inserted to counter act the increase in stress.

AVAILABLE BONE HEIGHT
The minimum height of available bone for endosteal
implants is in part related to the density of the bone. The more
dense bone may accommodate a shorter implant and the least
dense bone requires a longer implant. Once the minimum
implant height is established for each implant design, the width
is more important than additional length. The height of the
available bone is measured from the crest of the edentulous
ridge to the opposing landmark such as the maxillary sinus or
mandibular canal in the posterior regions. The anterior regions
are limited by the nasal nares or the inferior border of the
mandible. The mandibular first premolar region may present
reduced height of available bone compared with the anterior
region because of the anterior loop of the mandibular canal as
it passes below the foramen and proceeds superiorly then
distally before it exits through the mental foramen.www.indiandentalacademy.com

AVAILABLE BONE WIDTH
The width of available bone is measured between the
facial and lingual plates at the crest of the potential implant site.
Once adequate height is available for implants, primary criteria
affecting long term survival of endosteal implants is the width of
the available bone. Root form implants of 4mm crestal diameter,
usually require 5mm of bone width to ensure sufficient bone
thickness and blood supply around the implant for predictable
survival.

AVAILABLE BONE ANGULATION
Bone angulation is aligned with the forces of occlusion and
is parallel to the long axis of the prosthodontic restoration.
Alveolar bone angulation represents the root trajectory in
relation to the occlusal plane. Rarely this bone angulation
remains constant after the loss of teeth especially in the anterior
edentulous maxillary arch. The limiting factor of angulation of
force between the body and the abutment of an implant is
correlated to the width of the bone. The implant body may be
inserted so as to reduce the divergence of the abutments.
Therefore, the acceptable bone anglation and the wider ridge
may be as much as 30º.

PRE-IMPLANT CONSIDERATIONS
The pre-implant prosthodontic evaluation of the
patients overall condition closely resembles traditional
dentists. However, specific conditions may modify and
hinder the course of implant treatment if overlooked and
should be considered before a final treatment plan in
presented to the patient.

The conditions include the following:
1. Existing occlusion
2. Existing occlusal plane, orientation
3. Interarch space
4. Existing vertical dimension of occlusion
5. Maxillomandibualr arch relationship
6. TMJ status
7. Existing prosthesis
8. Arch form
9. Implant ideal permucosal position
10. Missing teeth – location
11. Missing teeth - number
12. Lip line at rest and during speech
13. Mandibular flexion
14. Soft tissue support.

Centric occlusion is the tooth position of maximal
intercupsation . Its relationship to centric relation is noteworthy
to the restoring prosthodontist because of the potential need of
occlusal adjustments to eliminate deflective tooth contours.
A proper curve of spee and curve of Wilson are indicated
for proper aesthetics and to prevent posterior lateral interferences
during excursions. The occlusal plane is evaluated in relationship
to the final implant prosthesis. Odontoplasty, endodontic therapy
and /or crowns are indicated to remedy tipping and /or extrusions
of adjacent or opposing natural teeth. A pretreatment diagnostic
wax-up is strongly suggested to evaluate these needed changes
before implant placement.
The interarch space depends on the type of restoration and
requires at least 7mm in the posterior regions and 8-10mm in the
anterior regions of the mouth for fixed restorations. This permits
enough space for occlusal material strength and aesthetics,
abutment height retention and hygiene considerations.

Removable prosthesis often require 12mm or more of interarch
space for denture teeth and acrylic base strength, attachments, bars and
hygiene considerations.
Several conditions relate to arch relationship. Arch relationship
often concerns the anterior regions of the maxilla and mandible. The
anterior edentulous maxilla resorb towards the palate. The width of the
alveolar ridge decreases 40% within a few years primarily at the
expense of the labial plate. Consequently, implants are often placed
lingual to the original tooth position. Final restoration is consequently
over contoured to place the incisal 2/3rd
in the ideal position for
aesthetics. The incisal edge position is facial to the remaining bone. This
results in a cantilevered force on the anterior implant body. An anterior
cantilever on implants in the mandibular arch may correct and Angle’s
Class II jaw relationship. Transversal arch relationships include the
existence of posterior cross bites which occur frequently in implant
dentistry. When mandibular sub-periosteal implants are used for
implant support posterior teeth maybe placed in a cross bite to decrease
the moment forces developing on the maxillary posterior teethwww.indiandentalacademy.com

Existing prosthesis are evaluated for proper design and
function. A removable partial soft tissue supported restoration
opposing the proposed implant supported prosthesis is of particular
interest. The occlusal forces vary widely as the underlying bone
remodels. The aesthetics of the existing prosthesis that will be
replaced by implant supported restoration are evaluated. The
contour, arrangement and position of the teeth in an acceptable
restoration all influence the future implant prosthesis design.
The position of the implant abutment is of particular
importance for prosthesis. An implant placed in improper position
can compromise the final results in aesthetics, biomechanics and
maintenance. The most compromising position for an implant is too
facial resulting in compromised aesthetics, phonetics, lip support
and function. An angulated abutment may help improve the
condition if the improper placement is not severe. But the facial
gingival contour remains compromised.

The number and location of missing tooth influence the
prosthodontic treatment plan of the patient. For most cases the
second molar is not replaced in posterior implant supported
prosthesis. The mandibular first molar is designed to occlude
with the marginal ridge of a natural second molar to prevent
extrusion.
The lip positions are evaluated including resting lip line,
maxillary high lip line and mandibular low lip line. The resting
lip line is especially noted if maxillary anterior teeth are to be
replaced.
Ridge parallelism is also evaluated. Having both ridges
parallel to the occlusal plane is most favourable. If both ridges
are divergent, stability of the denture will be greatly affected.

Review of literature
Jacob RF Reece GP Taylor TD Miller MJ
Mandibular restoration in the cancer patient: microvascular surgery
and implant prostheses. (In: Tex Dent J (1992 Jun) 109(6):23-6)
This article deals with state of the art reconstruction and
rehabilitation of the head and neck cancer patient who requires
mandibular resection. The mandible can be reconstructed by
microvascular free tissue transfer of bone and soft tissue from
distant body sites. The dental units and missing soft tissue contours
can be supported by osseointegrated implants placed in the grafted
bone. This article discusses the rationale for patient selection and
sequencing of this complex and rewarding rehabilitation.

Larsen PE Stronczek MJ Beck FM Rohrer M
Osteointegration of implants in radiated bone with and without
adjunctive hyperbaric oxygen. (In: J Oral Maxillofac Surg (1993 Mar)
51(3):280-7)
A study was undertaken to evaluate the integration of
endosseous implants in rabbit tibias that had received a tumoricidal
dose of radiation. The effect of hyperbaric oxygen on integration in this
compromised situation was also evaluated. Despite clinical and
radiographic evidence of success of all implants, there was a significant
decrease in amount of histologic bony integration of implants placed in
the tibias that had received radiation therapy when compared to
contralateral control implants. Adjunctive hyperbaric oxygen therapy
significantly improved the amount of histologic integration of implants
placed within the radiated tibias evaluated at 10 and 16 weeks after
placement. Hyperbaric oxygen was also associated with better soft
tissue wound healing in the radiated surgical site. Increased integration
time significantly improved the amount of histologic integration in the
animals that did not receive hyperbaric oxygen.www.indiandentalacademy.com

Johnsson K Hansson A Granstrom G Jacobsson M Turesson I
The effects of hyperbaric oxygenation on bone-titanium implant
interface strength with and without preceding irradiation.
(In: Int J Oral Maxillofac Implants (1993) 8(4):415-9)
This study investigated the influence of a single 15-Gy dose
of irradiation on the capacity of titanium screws to integrate in
irradiated bone tissue. The biomechanical force necessary to
unscrew the titanium implants 8 weeks after placement was 54%
lower for implants in irradiated bone tissue compared to implants
in nonirradiated bone tissue. Postirradiation use of hyperbaric
oxygen treatment (2-hour daily treatments for 21 days) increased
the biomechanical force necessary to unscrew the titanium
implants by 44% in irradiated bone and by 22% in nonirradiated
bone.

Franzen L Rosenquist JB Rosenquist KI Gustafsson I
Oral implant rehabilitation of patients with oral malignancies
treated with radiotherapy and surgery without adjunctive
hyperbaric oxygen. (In: Int J Oral Maxillofac Implants (1995 Mar-
Apr) 10(2):183-7)
Five patients treated with radiotherapy and surgery for oral
malignant tumors had a total of 20 Brånemark implants placed in
irradiated bone of the mandible. The radiotherapy dose varied
between 25 and 64 Gy (mean 40.3 Gy) with a biologically effective
dose varying between 33.4 and 106.9. One implant did not
osseointegrate, but 19 remain stable after 3 to 6 years of
observation. The oral surgery procedures were carried out without
adjunct hyperbaric oxygen therapy, and the successful results
support the view that such adjunctive measures are not always
necessary in the oral rehabilitation after radiotherapy.

Esposito M, Hirsch JM, Lekholm U, Thomsen P
Biological factors contributing to failures of osseointegrated oral implants. (I).
Success criteria and epidemiology. (European Journal of Oral Sciences
106(1):527-51, 1998 Feb)
Radiographic examinations together with implant mobility tests seem to
be the most reliable parameters in the assessment of the prognosis for
osseointegrated implants. Biologically related implant failures calculated on a
sample of 2,812 implants were relatively rare: 7.7% over a 5-year period (bone
graft excluded). The predictability of implant treatment was remarkable,
particularly for partially edentulous patients, who showed failure rates about half
those of totally edentulous subjects. Analysis also confirmed (for both early and
late failures) the general trend of maxillas, having almost 3 times more implant
losses than mandibles, with the exception of the partially edentulous situation
which displayed similar failure rates both in upper and lower jaws. Surgical
trauma together with anatomical conditions are believed to be the most
important etiological factors for early implant losses (3.60% of 16,935 implants).
The low prevalence of failures attributable to peri-implantitis found in the
literature together with the fact that, in general, partially edentulous patients
have less resorbed jaws, speak in favour of jaw volume, bone quality, and
overload as the three major determinants for late implant failures in the
Branemark system. Conversely, the ITI system seemed to be characterized by a
higher prevalence of losses due to peri-implantitis. These differences may be
attributed to the different implant designs and surface characteristics.

Esposito M, Hirsch JM, Lekholm U, Thomsen P
Biological factors contributing to failures of osseointegrated oral implants.
(II). Etiopathogenesis. (Eur J Oral Sci 1998;106(3):721-64.)
The aim of the present review is to evaluate the English language
literature regarding factors associated with the loss of oral implants. An
evidence-based format in conjunction, when possible, with a meta-analytic
approach is used. The review identifies the following factors to be
associated with biological failures of oral implants: medical status of the
patient, smoking, bone quality, bone grafting, irradiation therapy,
parafunctions, operator experience, degree of surgical trauma, bacterial
contamination, lack of preoperative antibiotics, immediate loading,
nonsubmerged procedure, number of implants supporting a prosthesis,
implant surface characteristics and design. Excessive surgical trauma
together with an impaired healing ability, premature loading and infection
are likely to be the most common causes of early implant losses. Whereas
progressive chronic marginal infection (peri-implantitis) and overload in
conjunction with the host characteristics are the major etiological agents
causing late failures. Furthermore, it appears that implant surface
properties (roughness and type of coating) may influence the failure
pattern. Various surface properties may therefore be indicated for different
anatomical and host conditions. Finally, the histopathology of implant
losses is described and discussed in relation to the clinical findings.www.indiandentalacademy.com

Tong DC, Rioux K, Drangsholt M, Beirne OR
A review of survival rates for implants placed in grafted maxillary
sinuses using meta-analysis. (International Journal of Oral &
Maxillofacial Implants 13(2):175-82, 1998 Mar-Apr)
A variety of materials and procedures are used to create
adequate bone volume in the maxillary sinus for placement of
endosseous implants in the posterior atrophic maxilla. This review
used the structured method of meta-analysis to evaluate the survival of
the implants placed into various materials that have been used in the
maxillary sinus with the sinus lift procedure. A MEDLINE computer
search of the English literature yielded 28 studies that reported using
the maxillary sinus augmentation procedure to increase bone volume
for placement of endosseous implants; only 10 of these met the
inclusion criteria for meta-analysis. Data regarding immediate or
delayed placement of implants were combined to simplify analysis.
Implant survival was 90% for autogenous bone (484 implants in 130
patients followed for 6 to 60 months), 94% for the combination of
hydroxyapatite (HA) and autogenous bone (363 implants in 104
patients followed for 18 months), 98% for the combination of
demineralized freeze-dried bone (DFDB) and HA (215 implants in 50
patients followed for 7 to 60 months), and 87% for HA alone (30
implants in 11 patients followed for 18 months).

Lindh T, Gunne J, Tillberg A, Molin M
A meta-analysis of implants in partial edentulism.
Clinical Oral Implants Research 9(2):80-90, 1998 Apr
A meta-analytic technique was used to estimate the
survival of implants supporting bridges or single crowns in
partially edentulous patients. A survey of the literature
revealed 66 studies, published between 1986 and 1996. Nine
studies on single implants and 10 studies on fixed partial
dentures met the inclusion criteria for the meta-analysis.
Data from a total of 2686 implants, 570 single crowns (SC)
and 2116 in fixed partial dentures (FPD), were analyzed. In
order to calculate annual survival rates for individual
studies a life-table analysis was conducted. Maximum
follow-up time ranged between 1 and 8 years. After 1 year
the success rate was calculated to be at least 85.7% for FPD
and 97.2% for SC. When the results from the FPD studies
were pooled the survival rate was 93.6% after 6-7 years. The
corresponding value for SC was 97.5%.www.indiandentalacademy.com

Cochran DL
A comparison of endosseous dental implant surfaces. (Journal of Periodontology
70(12):1523-39, 1999 Dec)
Endosseous dental implants are available with various surface characteristics
ranging from relatively smooth machined surfaces to more roughened surfaces created by
coatings, blasting by various substances, by acid treatments, or by combinations of the
treatments. Meta-analyses were performed on all implants in all locations, on implants
placed only in the maxilla or the mandible, and, finally, on implants placed in the maxilla
compared to implants placed in the mandible. Evaluation of the data revealed that
predictably high success rates can be achieved for implants with both rough and smooth
titanium surfaces and for hydroxyapatite-coated implants. When studies were clustered by
specific indications or patient populations, rough surfaced implants had significantly
higher success rates compared to implants with more smooth surfaces except in the case
of single tooth replacements where the success rates were comparable. In general,
implants placed in the mandible had significantly higher success rates than implants
placed in the maxilla. However, in the partially edentulous patient group, titanium implants
with a rough surface had significantly higher success rates in the maxilla compared to the
mandible and, in cases of single tooth replacement, success rates were similar in the
maxilla and in the mandible as was the case for hydroxyapatite-coated implants. The
documented advantage of implants with a roughened surface in animal and in vitro
experiments has been demonstrated in clinical cases when studies were compared in
which specific indications or patients were treated. Additionally, implants placed in the
mandible have, in general, higher success rates than implants placed in the maxilla, with
only a few exceptions noted. These data from human clinical experiences support the
documented advantage of implants with a roughened surface in animal and in vitro
experimentation and indicate that the magnitude of the advantage is significant for patient
care.

Esposito M, Hirsch J, Lekholm U, Thomsen P.
Differential diagnosis and treatment strategies for biologic
complications and failing oral implants: a review of the literature.
(Int J Oral Maxillofac Implants 1999;14(4):473-90)
The aim of this article was to review the literature on differential
diagnosis and treatment of biologic complications and failing implants.
All types of publications, with the exception of abstracts, published in
English up to December 1998, were included. A multi-layered search
strategy was used. Controlled clinical trials (CCTs) were searched in the
Cochrane Oral Health Group's Specialized Register of Trials. This
database contains all CCTs identified in MEDLINE and EMBASE.
PubMed was searched using various key words and the "related
articles" feature. All identified publications were obtained and none
were excluded. Infection, impaired healing, and overload are considered
the major etiologic factors for the loss of oral implants. Only a few
clinical and animal investigations were found that tested the validity of
the proposed therapeutic approaches. The treatment of failing implants
is still based mainly on empirical considerations, often derived from
periodontal research, from data extrapolated from in vitro findings, or
from anecdotal case reports performed on a trial-and-error basis.www.indiandentalacademy.com

Ivanoff C-J. - Gröndahl K. - Bergström C. - Lekholm U. - Brånemark P-I.
Influence of bicortical or monocortical anchorage on maxillary implant
stability: A 15-year retrospective study of Brånemark system implants.
(February 2000 - Int. J of Oral & Maxillofacial Implants - Vol. 15 No. 1 pp
103-110.)
` Numerous factors relating to bone quality have been cited with
respect to stress distribution at the bone-to-implant interface. One such
factor is the role and influence of cortical fixation, both mono- (MCF) and
bi-cortical fixation (BCF). To date BCF has been deemed by clinicians to
be beneficial and experimentally it has been shown to yield increased
torque resistance and an increase in percentage bone-to-implant contact.
However calculations from Finite Element Analyses (FEA) and
photoelastic studies have yielded conflicting results, indicating that BCF
may be less than ideal, with an influence over the pattern of stress
concentration which becomes located in the crestal regions. This has been
associated with an under stimulation of the cancellous compartment. Few
data exist from long-term clinical studies. To this end a retrospective
assessment of data gathered over 15 years was undertaken to compare the
outcome for implants placed in the maxilla benefiting from either MCF or
BCF.

Creugers NH, Kreulen CM, Snoek PA, de Kanter RJ
A systematic review of single-tooth restorations supported
by implants. (Journal of Dentistry 28(4):209-17, 2000 May)
A three-step inclusion/exclusion procedure was
applied to identify papers that represented: good scientific
practice (GSP), reported results of all patients, implants and
crowns for more than 2years, and had sufficient data to
generate life-table analyses. The outcomes were 'implant
failure' and 'crown completion'. Nine studies survived.
These data showed an overall mean GSP of 0.37 with a
predicted 4year implant survival of 97% (n=459), and an
uncomplicated crown maintenance of 83% (n=240). Single-
tooth implants show an acceptable short-term survival of
4years, but crown complications are common.

Lee JJ, Rouhfar L, Beirne OR
Survival of hydroxyapatite-coated implants: a meta-analytic
review. (Journal of Oral & Maxillofacial Surgery 58(12):1372-
9; discussion 1379-80, 2000 Dec)
The survival rates reported for HA-coated implants
were similar to the survival rates reported for uncoated
titanium implants. If resorption of the HA coating causes
late failure of implants, the yearly interval survival rates
should have decreased with increased years of follow-up.
This decrease was not observed in the longitudinal human
clinical trials that met the selection criteria for this study.
Detailed analysis of these clinical trials did not show that
HA-coating compromises the long-term survival of dental
implants.

Sadowsky SJ
Mandibular implant-retained overdentures: a literature
review.
(Journal of Prosthetic Dentistry 86(5):468-73, 2001 Nov)
The implant-retained overdenture for the mandible has
been shown to be a highly successful prosthetic treatment
similar to the fixed implant denture. However, controversy
persists as to its design and indications. Few literature
reviews have been published on the topic. This article
critically analyzes the existing mandibular implant
overdenture literature relative to bone preservation, effect on
antagonist jaw, number of implants required, anchorage
systems, maintenance, and patient satisfaction. A MEDLINE
search was completed (from 1987 to 2001), along with a
manual search, to locate relevant English-language articles
on mandibular implant overdentures. Twelve treatment
concepts are elucidated from a distillation of the literature

Boioli LT, Penaud J, Miller N
A meta-analytic, quantitative assessment of osseointegration establishment and
evolution of submerged and non-submerged endosseous titanium oral implants.
(Clinical Oral Implants Research 12(6):579-88, 2001 Dec)
Two implant placement methods are used in oral implantology:
submerged (S, two-stage surgical procedure) and non-submerged (NS, one-stage
surgery). However, a quantitative assessment of their influence on implant
osseointegration, summarising the whole present experience, is not directly
possible, owing to the lack of normalisation of the published results. To overcome
this difficulty, selection criteria have been applied to the latter in a process of a
meta-analysis of specialised literature, in order to authorise a pooled treatment
with an adequate statistical method. Survival life tables are established (up to 15
and 10 years respectively for S and NS implants placed in normal situations) for
extended samples (13049 S and 5515 NS implants). Early (before loading) failure
rates and 95% confidence level ranges of cumulative implant survival rates are
shown. For both categories, the quality of the placement stage remains critical to
ensure optimal osseointegration behaviour. Both categories match current
survival requirements, but with a quite different behaviour over time. NS implants,
while osseointegrating better initially, are subject to causes of osseointegration
loss, which persist over a longer period of time. Implant design characteristics
(including the type of surface) seem to be more relevant than the placement
procedure for the implant's behaviour. This is in agreement with recent
histological and preliminary clinical results, and should be confirmed by further
studies. www.indiandentalacademy.com

Quirynen M, De Soete M, van Steenberghe D.
Infectious risks for oral implants: a review of the literature. (Clin Oral Implants
Res. 2002 Feb;13(1):1-19)
The use of oral implants in the rehabilitation of partially and fully
edentulous patients is widely accepted even though failures do occur. The
chance for implants to integrate can for example be jeopardised by the intra-
oral presence of bacteria and concomitant inflammatory reactions. The
longevity of osseointegrated implants can be compromised by occlusal
overload and/or plaque-induced peri-implantitis, depending on the implant
geometry and surface characteristics. Animal studies, cross-sectional and
longitudinal observations in man, as well as association studies indicate that
peri-implantitis is characterised by a microbiota comparable to that of
periodontitis (high proportion of anaerobic Gram-negative rods, motile
organisms and spirochetes), but this does not necessarily prove a causal
relationship. However, in order to prevent such a bacterial shift, the following
measures can be considered: periodontal health in the remaining dentition (to
prevent bacterial translocation), the avoidance of deepened peri-implant
pockets, and the use of a relatively smooth abutment and implant surface.
Finally, periodontitis enhancing factors such as smoking and poor oral
hygiene also increase the risk for peri-implantitis. Whether the susceptibility
for periodontitis is related to that for peri-implantitis may vary according to
the implant type and especially its surface topography.

References
1. Jacob RF Reece GP Taylor TD Miller MJ
Mandibular restoration in the cancer patient: microvascular
surgery and implant prostheses. (In: Tex Dent J (1992 Jun)
109(6):23-6)
2. Larsen PE Stronczek MJ Beck FM Rohrer M
Osteointegration of implants in radiated bone with and without
adjunctive hyperbaric oxygen. (In: J Oral Maxillofac Surg
(1993 Mar) 51(3):280-7)
3. Johnsson K Hansson A Granstrom G Jacobsson M Turesson I
The effects of hyperbaric oxygenation on bone-titanium implant
interface strength with and without preceding irradiation. (In:
Int J Oral Maxillofac Implants (1993) 8(4):415-9)

4. Franzen L Rosenquist JB Rosenquist KI Gustafsson I
Oral implant rehabilitation of patients with oral malignancies
treated with radiotherapy and surgery without adjunctive
hyperbaric oxygen. (In: Int J Oral Maxillofac Implants (1995
Mar-Apr) 10(2):183-7)
5. Esposito M, Hirsch JM, Lekholm U, Thomsen P
Biological factors contributing to failures of
osseointegrated oral implants. (I). Success criteria and
epidemiology. (European Journal of Oral Sciences
106(1):527-51, 1998 Feb)
6. Esposito M, Hirsch JM, Lekholm U, Thomsen P
Biological factors contributing to failures of
osseointegrated oral implants. (II). Etiopathogenesis. (Eur J
Oral Sci 1998;106(3):721-64.)www.indiandentalacademy.com

7. Tong DC, Rioux K, Drangsholt M, Beirne OR
A review of survival rates for implants placed in grafted
maxillary sinuses using meta-analysis. (International Journal
of Oral & Maxillofacial Implants 13(2):175-82, 1998 Mar-Apr)
8. Lindh T, Gunne J, Tillberg A, Molin M
A meta-analysis of implants in partial edentulism. (Clinical
Oral Implants Research 9(2):80-90, 1998 Apr)
9. Cochran DL
A comparison of endosseous dental implant surfaces.
(Journal of Periodontology 70(12):1523-39, 1999 Dec)
10. Esposito M, Hirsch J, Lekholm U, Thomsen P.
Differential diagnosis and treatment strategies for
biologic complications and failing oral implants: a review of the
literature. (Int J Oral Maxillofac Implants 1999;14(4):473-90)

11. Ivanoff C-J. - Gröndahl K. - Bergström C. - Lekholm U. -
Brånemark P-I.
Influence of bicortical or monocortical anchorage on
maxillary implant stability: A 15-year retrospective study
of Brånemark system implants. (February 2000 - Int. J of
Oral & Maxillofacial Implants - Vol. 15 No. 1 pp 103-110.)
12. Creugers NH, Kreulen CM, Snoek PA, de Kanter RJ
A systematic review of single-tooth restorations supported
by implants. (Journal of Dentistry 28(4):209-17, 2000 May)
13. Lee JJ, Rouhfar L, Beirne OR
Survival of hydroxyapatite-coated implants: a meta-
analytic review. (Journal of Oral & Maxillofacial Surgery
58(12):1372-9; discussion 1379-80, 2000 Dec)

14. Sadowsky SJ
Mandibular implant-retained overdentures: a literature
review. (Journal of Prosthetic Dentistry 86(5):468-73, 2001
Nov)
15. Boioli LT, Penaud J, Miller N
A meta-analytic, quantitative assessment of
osseointegration establishment and evolution of submerged
and non-submerged endosseous titanium oral implants.
(Clinical Oral Implants Research 12(6):579-88, 2001 Dec)
16. Quirynen M, De Soete M, van Steenberghe D.
Infectious risks for oral implants: a review of the
literature. (Clin Oral Implants Res. 2002 Feb;13(1):1-19)

17. Contemporary implant dentistry. Carl E. Misch
Second Edition.
18. Implant therapy. Nevins. Second Edition
19. Dental Implants; Dental Clinics of North America, Jan
1998.
20. Brånemark System of Oral Reconstruction.
Russmassan.
21. Surgical Manual of Oral Reconstruction. Brånemark

CONCLUSION
Patients who are partially or fully edentulous are
better served with tissue integrated prosthesis rather than
other classical forms of therapy. However, not all patients can
or should be considered suitable for this procedure.
The first step in the clinical protocol is a thorough
medical and dental evaluation to screen out those patients
who can be better served by an alternate treatment modality.
The patient must be viewed in totality and the end
result visualized prior to the surgery. The “reverse approach”
means the anticipated prosthetic result should be determined
prior to surgery.

Selection of dental implant patients/ prosthodontic courses

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