PROSTHODONTIC EVALUATION FOR IMPLANT TREATMENT PLANNING

DEPARTMENT OF PROSTHODONTICS & CROWN AND BRIDGE & ORAL IMPLANTOLOGY, DDCH, UDAIPUR
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PROSTHODONTIC
EVALUATION FOR
IMPLANT TREATMENT
PLANNING
PRESENTED BY:
Dr. JEHAN DORDI
III YEAR POST GRADUATE

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• Prosthetic options in implant dentistry
• Extra-oral evaluation
• Smile line
• TMJ evaluation
• Lip lines
• Intra-oral evaluation
• Type of edentulism
• Arch relationship
• Arch form
• Opposing and adjacent teeth at occlusal position
CONTENTS

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• Available space for different prosthesis
• Diagnostic casts
• Diagnostic templates
• Occlusal consideration
• Available bone: Influence on prosthetic treatment planning
• Bone density: Influence on prosthetic treatment planning
• Conclusion
Contents conti..

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PROSTHETIC OPTIONS IN IMPLANT

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• The benefits of implant dentistry can be realized only when the full range of
available prosthetic options for the final prosthesis is first evaluated by the
practitioner and then presented to the patient.
• Thus, it is important to first visualize the intended final prosthesis based on
which the existing bone is evaluated to determine the type and number of
implants necessary to support the intended prosthesis.
• The ultimatum of the patients is finally the teeth in their oral cavity and not the
implant and best of the results are achieved if implant placement and planning
are prosthodontically driven.

In 1989, Misch proposed five prosthetic options:
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PROSTHETIC OPTIONS
TYPE DEFINITION
FP-1 FP which replaces only the crown and appears like a natural tooth
FP-2 FP which replaces the crown and a portion of the root. Crown contour appears
normal in the occlusal half but is elongated or hyper-contoured in the gingival half
FP-3 FP which replaces missing crowns and gingival color and portion of the
edentulous site
FP-1 FP-2 FP-3

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PROSTHETIC OPTIONS
TYPE DEFINITION
RP-4 RP which is mainly an overdenture completely supported by implants
RP-5 RP which is an overdenture supported by both soft tissue and implant
RP-4 RP-5

A newer classification is proposed for Fixed Prosthesis (FP) based on
method of retention:
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Class I prosthetic
design: Individual
crowns are
cemented on the
abutments.
Class II prosthetic
design: Individual
crowns are screw
retained on the
implants.
Proussaefs P, AlHelal A, Taleb A, Kattadiyil MT. Adjacent Dental Implants Classification Based on Restorative Design. J Oral Implantol. 2017 ;43(5):405-9.

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Class III
prosthetic
design: Individual
screw-retrievable
cement-retained
prosthesis are
made.
Class IV prosthetic
design: Splinted
crowns are
cemented on the
abutments.

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Class V prosthetic
design: Splinted
crowns are screw
retained on the
implants.
Class VI prosthetic
design: Splinted
crowns are designed
to be screw
retrievable/cement
retained on the
implants.

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EXTRAORAL

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Smile Line:
The LARS factors as described by Ahmed et al, provides information for
determining the appropriate display of the maxillary anterior teeth. These
factors are:
Lip length: Short, medium, large
Age: Elder persons typically show less of maxillary and more of
mandibular teeth
Race: African descent patients frequently display less of maxillary
anterior teeth than Caucasian descent patient
Sex: Females generally show twice as much of the maxillary incisors as
male.
Ahmad I. Vital guide to Aesthetic dentistry. Vital. 2006 Jun;3(2):19-22.

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TMJ Examination must be done to:
Check any dysfunction
Maximal opening
Deviation
Unrestricted mandibular moments

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Lip lines:
The lip positions should be evaluated, with lip at rest as well as during the
smiling, when the implant therapy is given in the aesthetic region as well
as for the full mouth fixed as well as removable implant prosthesis.
The maxillary lip lines, when the patient smiles, are of three categories.

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Low lip line:
It shows no interdental papillae during
smiling.
They do not expose the complete crown
height and soft tissue, any prosthesis
which looks ideal in the incisor half may
satisfy their aesthetic demands.

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Medium lip line:
This type of smile exposes the clinical
crown as well as the interdental papillae
and providing aesthetic implant therapy in
such patients is a great challenge.
All efforts should be made to preserve any
existing interdental papillae; if lost, it should
be regenerated with the soft tissue
manipulation and grafting techniques.

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High lip line (gummy)
This type of smile exposes the entire clinical
crown, the interdental papillae, and the full gingival
margin above the teeth.
Vertical ridge reduction and restoration with the
ceramic prosthesis with a gingival colored cervical
ceramic, is the treatment of choice.

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For all the above three categories, if the patient is completely edentulous,
the removable prosthesis over the implant is the treatment of choice to
achieve high aesthetic results.
The use of pre-fabricated teeth and denture flanges for lip support give a
satisfactory maxillofacial aesthetic outcome.

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INTRA-ORAL EVALUATION

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TYPE OF
EDENTULIS
M
CONTI…

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Based on classification by Misch and Judy (1985)
partially edentulous arches can be classified as:

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Class I: Partially edentulous
arches with bilateral edentulous
areas posterior to remaining
natural teeth. Class I is further
divided into 4 divisions
Division A:
Edentulous areas have abundant
bone height more than 10mm and
length more than 7mm for endosteal
implant.
Direction of load is within 30 degrees
of implant body axis.
Crown implant ratio is less than 1.
Root form implants and independent
prosthesis are often indicated

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Division B:
Edentulous areas have moderate available bone width 2.5-5mm and atleast
adequate bone height more than 10mm and length 15mm.
Direction of load is within 20 degrees of implant axis.
Crown implant ratio is less than 1.
Surgical options include osteoplasty, small diameter implants and/ or
augmentation.

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Division C
Edentulous area have inadequate
available bone for endosteal implants
with a predictable result because of
two little bone width (C-w), length,
height (C-h) or angulation of load.
Crown implant ratio is more than 1.
Surgical options for C-w includes
osteoplasty or augmentation; for C-h
sub-periosteal implants or
augmentation.
Root forms maybe considered with
augmentation and or nerve

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Division D:
Edentulous areas have severely resorbed
ridges involving a portion of basal or
cortical supporting bone.
Crown implant ratio is more than 5.
Surgical options usually require
augmentation before implants can be
inserted.

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Class II: Partially edentulous arches
with unilateral edentulous areas
posterior to remaining natural teeth.
Division A-D are same as for class I.

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Class III: Partially edentulous arch with
unilateral edentulous areas with
natural teeth remaining anterior and
posterior.

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Class IV: Partially edentulous arch
with edentulous area anterior to
remaining natural teeth and crosses
the midline.

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Classification of Completely Edentulous Arches
The edentulous jaw is divided into three
regions and described according to the
Misch–Judy classification.
The division of bone in each section of
the edentulous arch determines the
classification of the edentulous jaw. The
three areas of bone are evaluated
independently from each other.
Therefore, one, two, or three different
divisions of bone may exist.

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Type 1: In this type of edentulous arch, the bone is
symmetrical and similar in all the 3 segments.
According to volume of bone present, the division of
bone is written with type 1:
Type 1 division A: Symmetrical
bone in all 3 segments with abundant
bone present.
The patient may use as many root
form implants as needed and
whenever desired to support the final
prosthesis.
The type 1, division B: Edentulous ridge presents adequate bone in all
3 sections in which to place narrow-diameter root form implants. It is
common practice to modify the anterior section of bone in the mandible
by osteoplasty to a division A and to place full-size root form implants in
this region.

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Type 1 division C-h: Symmetrical bone
present in all the 3 segments with an
inadequate bone having a deficiency in
height. Implant supported removable
prosthesis is indicated to reduce occlusal
loads.
Type 1 division C-w: Ridge has
inadequate bone width for implantation. It
can be converted to C-h ridge by
osteoplasty.
Type 1 division D: Ridge offers the
greatest challenge and implant failure at the
time of placement or after many years may
result in mandibular fracture.

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Type 2: Here the posterior segments of bone is similar but differs from
anterior segments.
The classification of bone is written as Type 2 + Division of bone in
anterior segment+ Division of bone in posterior segment. For eg:
Type 2 division A, B arch Type 2 division A, C-h arch

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Type 3: In this type posterior segments have different bone levels.
After writing the type, the anterior bone volume is listed first, followed by
the division of bone in right posterior segment followed by left posterior
segment. For eg:
Type 3 division A, B, C arch Type 3 division C, D, C arch

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ARCH
RELATIONSHIP
CONTI…

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Ideal inter arch distance:
Posterior: 7mm
Anterior: 8-10mm
Increased space:
Results from vertical loss of alveolar
bone and soft tissues.
Increased space makes the
placement of removable prosthesis
easier.
In fixed restoration increased space
makes replacement teeth elongated.
Increased crown height increased
moment of force on implant
increased risk of component and
material fracture.

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Management of increased inter arch
space:
Can be decreased by addition of onlay
grafts before implant placement.
Autogenous and/or membrane grafts.
Alloplastic graft
Removable prosthesis
It improves…..
Crown-implant ratio
Esthetics
Permits wider implant
selection
Benefit of increased surface
area
Improves hygiene condition

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Lack of inter arch space results from:
Migration of opposite natural dentition into
the edentulous space.
History of tooth abrasion, attrition and
skeletal insufficiencies.
Even when the opposing teeth are extracted
or missing the inter arch space is still less
as the alveolar process has followed the
teeth.
Consequences:
Decreased abutment
height
Inadequate retention
Inadequate bulk for
esthetics and strength
Poor hygiene condition

3
Management of decreased inter
arch space:
Surgical reduction of tuberosities.
Osteoplasty and/ or soft tissue
reduction of implant region
Selective grinding
Prosthodontic restoration
Endodontic therapy

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ARCH FORM
INTRA-ORAL EVALUATION CONTI…

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The arch form influences the number and positions of the implants required
in fixed implant prosthesis for the edentulous maxilla and mandible.
Three types of dental arch forms are found in patients.

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Square arch: shows minimum facial
cantilevered forces; thus minimum number
of implants are required to support a full-
arch fixed or completely implant supported
removable prosthesis.
Only two implants are required at the
canine positions to restore the anterior
maxillary or mandibular region.
The full-arch, fixed, implant-supported
restoration (12–14 units) can be made
possible by placing only six implants (two at
canine, two at second premolar, and two at
first molar positions).

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Ovoid arch: shows more facial
cantilevered forces on the prosthesis
compared to the square arch form,
thus one more implant should be
added anterior to canines positions
(at one of the central incisor
positions) to reduce the cantilevered
forces on the rest of the implants.

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Tapering arch: has the maximum
facial cantilevered forces thus two
more implants should be added
anterior to canine positions (one at
each central incisor position) to
reduce the cantilevered forces on the
rest of the implants.

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The arch form is a critical element when
anterior implants are splinted with
posterior implants to minimize cantilever
forces.
The distance from the center of the
most anterior implant to a line joining
the distal aspect of the two most distal
implants is called the anteroposterior
distance or A-P spread.
A greater A-P spread is required in the
presence of anterior cantilevers.
When five anterior implants in the mandible are used for
prosthesis support, it has been recommended that the ratio of
the distal cantilever to the A-P spread should not exceed 2:5.

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The most ideal biomechanical arch form
depends on the restorative situation:
The tapering arch form is favorable for
anterior implants supporting posterior
cantilevers due to a greater A-P spread.
The square arch form is preferred when
canine and posterior implants are used to
support anterior teeth in either arch
The recommended anterior cantilever
dimension in the maxilla is less than that of
the posterior cantilever in the mandible
because the bone is less dense and forces
are directed outside the arch during

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OPPOSINGAND
ADJACENTTEETHAT
OCCLUSALPOSITION
CONTI…

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The teeth adjacent to and opposing the edentulous site should be
examined for any supra eruption inclinations, mesial drifting, etc. for
prosthetically guided implant insertion.

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Prosthetic planning before implant insertion avoids future problems
like
Unaesthetic prosthesis,
Recurrent dislodgement of prosthesis,
Implant component fractures,
Fractured prosthesis,
Loosening of the connection screw,
Implant body fracture,
Crestal bone resorption,
Implant failure, after implant is loaded/in function.
These problems usually arise because of offset occlusal forces and
extreme angulation of the implant prosthesis with the implant axis.

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AVAILABLE SPACE FOR DIFFERENT PROSTHESIS

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The minimum amount of vertical space required for implant
prostheses is as follows:
Fixed cement-retained: 7-
8 mm
Fixed screw-retained (implant level): 4-5 mm
Fixed screw-retained (abutment level): 7.5 mm
Carpentieri J, Greenstein G, Cavallaro J. Hierarchy of restorative space required for different types of dental implant prostheses J Amer Dent Asso. 2019 ;150(8):695-706.

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Fixed screw-retained hybrid:
15mm.
These dimensions represent the minimal amount of vertical rehabilitative space
that can accommodate the above implant prostheses.
Unsplinted overdenture: 7mm
Bar overdenture: 11 mm (for one arch)

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DIAGNOSTICCAST

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Upper and lower diagnostic casts must
be articulated in occlusion or in centric
relation. These diagnostic casts are
used:
1. To evaluate the patient’s opposing
tooth/teeth, their overeruption, buccal
or lingual inclinations, the drifting of
adjacent teeth, ridge form, etc.
2. Diagnostic casts enable these
prosthodontic factors, for example,
maxillo-mandibular relationships,
existing occlusion, and potential

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3. To fabricate a radiographic
template (using radiograph or CT
scan), which is used for accurate
planning of the implant.
4. To fabricate the surgical stent for
accurate implant placement.
5. For the fabrication of an interim
prosthesis after implant insertion.

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DIAGNOSTIC
TEMPLATES

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Although computed tomography (CT) procedures can identify the
available bone height and width accurately at a proposed implant site, the
exact position and orientation of the implant (which many times
determine the actual length and diameter of the implant) often are
dictated by the prosthesis.
A diagnostic template is most beneficial with this imaging technique.
Types of diagnostic templates:
Vaccuform template
Acrylic template
Template fabricated with radiopaque
denture teeth
Complex tomography template

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Vaccuform template:
This is produced by a vaccuform reproduction of the diagnostic cast and
has a number of variations:
The proposed restoration on the diagnostic wax-up is coated with a thin
film of barium sulfate.
This coating should be done before the fabrication of template. Due to this,
on CT examination, restorations become evident.

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Acrylic template:
Diagnostic wax-up provides an acrylic template.
A hole is drilled on the occlusal surface of proposed restorations followed
by filling this hole by gutta-percha.
This provides radiopacity of the proposed restoration on CT examination,
and precise position and orientation of proposed implant may be
identified by radiopaque plug of gutta-percha.

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Template fabricated with radiopaque denture teeth:
These radiopaque denture teeth are specifically manufactured for
implant imaging purposes and are used for the diagnostic wax–up and
subsequently are incorporated into the template.
If acceptable, it may be modified into a surgical template at a later
stage. This serves to transfer these findings to the patient at the time of
surgery.

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Complex tomography:
Diagnostic templates of CT examination are generally more precise than
tomography examination.
The simple method to produce tomography template is by placing 3 mm
ball bearing at proposed implant positions in vaccuform of diagnostic
cast.
Ball bearing can serve as a measure of magnification of the image.

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OCCLUSAL CONSIDERATION

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Elimination of premature contacts:
An occlusal analysis should be carried out to identify any premature
contacts during mandibular excursions.
An elimination of eccentric contacts may allow recovery of the
periodontal ligament health and muscle activity within 1–4 weeks.

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Bruxism:
The problem of bruxism should be treated before placing implants, to
avoid post loading problems, such as the early wearing of the
prosthesis, ceramic fractures, component fractures and crestal bone
resorption.

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Implant considerations for bruxers:
Additional implants preferably of greater diameter are indicated
Occlusal considerations – the anterior teeth may be modified to recreate the
proper incisal guidance to avoid posterior interferences during excursions.
In the presence of natural, healthy canines, a canine guided occlusion is the
occlusal scheme of choice.
If the canine is absent and is restored, then a mutually protected occlusion
is indicated.

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Night guard
A night guard should be given with even occlusal contacts around the
arch in centric occlusion and posterior dis-occlusion with anterior
guidance in all excursive movements.
The patient is advised to wear the device for a period of 4 weeks at night.
The night guard is then re-fabricated with 0.5–1 mm of acrylic resin on the
occlusal surface.

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AVAILABLE BONE: INFLUENCE ON PROSTHETIC TREATMENT PLANNING

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BONE VOLUME CLASSIFICATION
Misch classified bone volume into four groups, Division A, B, C and D
describing width and height.
Division A
Division A bone can be described as
abundant bone volume in height and
width.
The height is more than 10 mm and
the width is greater than 5 mm.
Bone modification procedures
(grafting and or osteoplasty) may be
avoided and result in less trauma to
the bone and a reduced healing

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Division B:
Division B bone presents itself with moderate bone volume in height and
width.
The height is more than 10 mm but the width at the crest atrophied to 2.5
mm to 5mm.
Deficient width can be overcome by the use of narrow diameter implants,
bone augmentation or osteoplasty.

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Division C:
Division C bone is characterized by compromised bone volume in height
and width.
The height is less than 10 mm and the width atrophied to less than 2.5 mm.
Either augmentation through block or sinus grafts before endosteal implant
placement or the use of sub-periosteal implants is the preferred treatment
modality.

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Division D:
Severely deficient bone volume in height and width indicates D4 bone.
Extensive sinus grafting, block grafts and particulate grafts are
necessary to achieve acceptable conditions for endosteal or sub-
periosteal implant placement.

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Different bone volume requires treatment plan approached
dental implant placement.
Misch and Judy (1985) have given a classification system for
the available bone with treatment options for all categories.

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PROSTHETIC OPTIONS AVAILABLE FOR VARIOUS DIVISION BONE
BONE
VOLUME
DIVISION
FP-1 FP-2 FP-3 RP-4 RP-5
Division A For ideal implant
placement and
natural esthetic
appearance of
final prosthesis
These prosthetic options may be
considered depending on amount of bone
loss and lip positions
These conditions may require
osteoplasty considering inter-arch
space to accommodate denture teeth
Division B ---- FP-2 or FP-3 restorations are indicated in
this condition to compensate increased
clinical height.
Osteoplasty to get Division A ridge is
mostly indicated in anterior mandible
because of fewer esthetic concerns in this
region.
---- ----
Division C More number of implants are required to expand implant bone surface area. In edentulous patients, RP-
5 prosthesis may be considered.
Division D Autogenous bone grafts is indicated to upgrade the division. Endosteal or sub-periosteal implants may
be inserted depending on the division of bone attained.

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BONE DENSITY: INFLUENCE ON PROSTHETIC TREATMENT PLANNING

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The strength of the bone supporting the endosteal implant is directly
related to its density.
Therefore, bone density exerts a significant influence on the clinical
success of implant therapy.
A range of implant survival has been found relative to location. The
anterior mandible has greater bone density than the anterior maxilla.
The posterior mandible has poorer bone density than the anterior
mandible.
The poorest bone density exists in the posterior maxilla and is
associated with dramatic failure rates.

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As the bone density decreases, the biomechanical loads on the
implants must be reduced. This can be accomplished in several ways
by considering the following prosthetic design.
Angle of load on the
implant body should be
more axial and offset loads
minimized.
Splinting the crowns of
adjacent implants with
relatively stiff.

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Narrower occlusal tables
should be designed.
Restorative materials may
be considered.

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Cantilever length may be shortened
or eliminated in case of full-arch
restorations for edentulous patients.
RP-4 rather than FP prosthesis may
be considered in edentulous patients
to reduce nocturnal parafunctional
forces.

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RP-5 prosthesis may be considered
to permit the soft tissue to share the
occlusal force.
Night guards and acrylic occlusal
surfaces distribute and dissipate the
parafunctional forces on an implant
system.

7

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The importance of biomechanics and the limitations of implant systems
were initially underestimated.
Over the years, clinical experience and research underscored the
importance of biomechanics in the success and predictability of implant-
retained prostheses.
The treatment planning for an implant restoration is unique regarding the
number of variables that may influence the therapy.

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Of prime importance is the recognition of the fact that a definitive
treatment plan should be developed sequentially to ensure the best
possible service.
The biomechanics must be factored into the planning at the beginning of
any implant treatment to achieve long-term, predictable success.

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PROSTHODONTIC EVALUATION FOR IMPLANT TREATMENT PLANNING

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