Prosthodontics Procedures and Complications - Posterior Quadrants

Prosthodontic procedures and
complications – Posterior quadrants
John Beumer III DDS, MS
Robert Faulkner DDS
Division of Advanced Prosthodontics, UCLA
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Exam and workup
l  Chief complaint
l  History of the present illness
l  Medical and dental history

Exam and workup
l  Missing teeth
l  Occlusal plane
l  Loss of OVD
l  Occlusal scheme

Exam and workup
l  Don’t forget that conventional
prosthodontic methods can be use address
many of these deficiencies

Selection of implants
l  Surfaces
l  Geometric designs

l  External hex vs. internal connection
l  Platform reduction
l  Geometric design of the neck
l  Location of the implant/abutment connection
l  Stability of the implant/abutment connection
l  One piece designs
l  Co-axis designs

Design of the implant body
l  Internal connections are more stable as compared to
external hex
l  Preferred in single tooth restorations
l  This issue is probably not clinically significant when splinting
non engaging multiple units together
l  Tapered implants achieve better primary stability
l  Preferred for immediate loading

Platform Switching (Reduction)
Will this type of implant fixture – abutment configuration
minimize the bone loss around the neck of implants?
v Based on a review by Bateli and Strub (2011) “the current literature
provides insufficient evidence about the effectiveness of any specific
modification in the implant neck area in preserving marginal bone or
preventing marginal bone loss”

Platform reduction
l  Recently conducted radomized clinical trials
indicate no advantage in terms of maintaining
marginal bone levels (Annibali et al 2012; Enkling
et al, 2013)

Geometric design of the neck
l  Positive slope vs negative slope
l  Presence of micro-threads
l  Evidence indicates there is no difference in marginal
bone loss

Location of the
implant/abutment connection
l  Subcrestal vs supracrestal
l  Evidence indicates there is no difference in
marginal bone loss

Stability
Implant/abutment connection
l  Multiple tooth restorations vs single tooth
restoration.
l  Size of the micro-gap
l  Bacterial colonization of the micro-gap

Marginal Bone Loss
Based on a Med Line search, a review of the literature
indicated that no implant system, surface or design
was found superior with regards to marginal bone loss
(Abrahamsson and Berhlundh, 2009)

One piece designs
Advantages
No implant abutment connection
Problems
l  Cement retained
l  Require intra-oral preparations
l Time consuming
l Difficult
l  Misaligned implants
l Difficulty in obtaining proper retention form
and resistance form

One piece systems
Nobel direct and similar one piece systems
There are no gaps developing between an
abutment and fixture. Why the bone loss?
Most have modern surfaces.
Many were immediately provisionalized and
loaded with cement retained restorations. In
many cases the cement extended down to
the boney levels
v An inflammatory response was initiated which was
progressive and irreversible leading to extensive
bone loss.

Co-axis designs
l  Desiged to account for
the anatomy of the
alveolar ridge
l  Permits subgingival
angulation correction
l  Issues
l  Biomehanics
l  Surgical placement
difficult

l  The best implant anchorage is achieved with
implants prepared with micro-rough surfaces and
they are dramatically superior to machine type
surfaces.
l  There appears to be no significant advantage of
platform reduction with respect to maintenance of
marginal bone or the long term survival of
implants.

l  On the basis of theoretical and laboratory studies, internal
connections are more stable and demonstrate smaller
micro-gaps when exposed to off angle loads.
l  Since these studies were based upon single tooth applications, it is
unclear whether there are clinically significant differences between
these two implant/abutment connection designs with regards to
splinted multi-implant prostheses.
l  Based on animal studies, implant/abutment connections
that are sub-crestal lead to more marginal bone loss than
connections that are equi-crestal or supra-crestal.
However, the evidence based on human studies is
indeterminate.

l  Properly designed, randomized clinical outcome
studies are not available assessing whether
internal connection implant/abutment interfaces
are superior to external hex designs when
restoring posterior quadrants with implant
supported fixed partial dentures.

Implant site evaluation and selection
Conventional methods
l  Diagnostic wax-up
l  Fabrication of a radiographic guide

Implant site evaluation and selection
l  Radiographic guide

l  The middle implant is tilted distally and medially in order to
maximize length and to enable anchoring the tip of the
implant in cortical bone
CAD-CAM

CAD-CAM
l  Scan the wax-up and proceed

CAD-CAM
l  Fabricate a model
l  From the model, make a surgical drill guide
(template)

CAD-CAM
l  Forego the 3D model
l  Identify implant positions

CAD-CAM
l  Change lengths, diameters, angulations etc. via
the internet with 3 - way consultation between the
surgeon, prosthodontist and the milling center.

CAD-CAM
l  The implant sites, implant lengths and diameter
have been chosen.
l  A surgical drill guide (template) can be milled or
made with a 3D printer
Inferior alveolar nerve

CAD-CAM
l  The surgical drill guide permits fully guided implant
placement

CAD-CAM
l  Such practice ensures that the implants will
be in the proper position and alignment and
the desired apical-coronal depth

CAD-CAM
l  These programs can also be used to
design and mill custom abutments

CAD-CAM
l  The definitive restorations. It has been
cemented. Note the supragingival margins.

l  These custom abutments
were designed before
placement of the
implants
CAD-CAM
Courtesy Dr. A. Pozzi

l  Definitive prosthesis
CAD-CAM

Abutment selection
v Prefabricated (stock)
v Cement retained
v  One piece
v  Two piece
v  Angled
v Screw retained
v  Angled abutments
v Prepable abutments
v UCLA abutment
v Custom abutments
v Conventional methods
v CAD-CAM designed and milled

Abutment selection
Cement vs screw retention
Screw retained restorations
l  Advantages
l  Retrievability – important if laminated porcelain is used to restore the
occlusal surfaces and repair or recontouring of the prosthesis is needed
l  When limited interocclusal space does not permit the development of axial
walls of sufficient thickness for proper retention and resistance form
l  Disadvantages
l  Screw access hole on the occlusal surfaces is unesthetic and may
compromise the position of occlusal contacts
l  Abutment screw retention requires perfect alignment and angulation of
implants
l  Cross linking screw retention requires skilled lab support and is costly

Abutment selection
Cement vs screw retention
Cement retained restorations
l  Advantages
l  Simplicity - It’s a common procedure in the dental office
l  Angulation problems are easier overcome
l  No screw access hole on the occlusal surfaces
l  Better esthetics
l  More control of occlusal contacts
l  Disadvantages
l  The margin is not scalloped to follow the gingival margin making it
difficult to remove subgingival cement
l  Subgingival cement retention – peri-implantitis can lead to loss of the
implants and adjacent teeth
l  Most dentists are not familiar with the techniques used to cement an
implant retained prosthesis
l  If the abutment screw becomes loose, the restoration will probably be
destroyed while gaining access to the screw

Abutment selection
Prefabricated vs custom abutments
Cemented restorations
Custom abutments are preferred because:
l  Better control the thickness of metal and porcelain
making chipping and fracture of the occlusal surfaces
less likely
l  Control the margin of the restoration in relation to the
gingival margins making it easier to retrieve cement

v  Carry restoration more subgingivally than we can
predictably remove cement.
v  For more ideal emergence profile and contour.
v  Avoid trapping cement subgingivally
v  More predictable seating of bridge or pontic
v  Better retention particularly when a cemented
restoration would have a very short axial wall.
v  Easier to restore when there is limited inter-
occlusal or restorative space
Arguments in favor of screw retained restorations

Abutment selection
Prefabricated vs. custom abutments
Cement retained implant crowns with laminated
porcelain occlusal surfaces
When a metal ceramic crown is fabricated to engage a stock
abutment, often the metal core is uneven and excessively thick.
Residual stress can build up during addition of the porcelain
predisposing to chipping and fracture of the prosthesis.

Abutment selection
Prefabricated vs. custom abutments
l  The position of the margin can
be controlled with custom
abutments. It is difficult to
remove cement when it
becomes impacted
subgingivally.
Prefabricated abutments
Prefabricated abutments
Custom abutments

Abutment selection
Prefabricated (stock)
l  Cement type
One piece system
Problem – Cement margin is often
several mm subgingival making
removal of cement problematic
Two piece system

Abutment selection
Prefabricated – Screw retained
Issues and concerns
l  Loosening and fracture of prosthetic screws

Abutment selection
Prefabricated – Screw retained
Angled abutments
Issues and concerns
l  Biomechanics
l  Emergence profile
l  Esthetics

Abutment selection
UCLA abutment
l  The restoration directly
engages the head of the
implant fixture without an
intervening abutment

Abutment selection
UCLA abutment
Advantages
l  No cement margin
l  Porcelain extended subgingivally
l  Can be used when there is
minimal interocclusal space
l  Account for poor angulation
Disadvantages
l  Abutment screw access
hole on the occlusal surface

Abutment selection
UCLA abutment
Can be used to make custom abutment for either a cement
retained or screw retained (cross pinning screws) prosthesis
1.  Used to overcome misaligned implants
2.  Used when a porcelain occlusal surface is desired

Abutment selection
Prepable abutments
Issues
l  Misangled implants
l  Time

Custom abutments
Two methods of fabrication
Conventional CAD-CAM
l  Account for difficulties in alignment, position and angulation
l  Better control of occlusal factors such as width of the occlusal table
l  Permits the use of a cemented restoration with complete
control of margin placement

Custom abutments
l  These custom abutments were designed to
retain the prosthesis with cross pinning screws

Custom abutments
CAD – CAM method
l  These abutments were milled from titanium, nitrite coated.
They are designed to retain the prosthesis with cement

Custom abutments
CAD – CAM method
Design criteria
l  Anatomic form/contour
abutment
l  They are designed according to
the emergence profiles of teeth
being replaced and often blanch
the tissue when seated. They are
generally not used in the esthetic
zone.

Custom abutments
CAD – CAM method
Design criteria
l  Support contoured
l  Abutment designed to
support the soft tissue
contoured with a provisional
restoration.

Custom abutments
CAD – CAM method
Design criteria
l  No tissue displacement
l  These abutments are
slightly under contoured,
and are often used when a
stock healing abutments
have been employed.

Custom abutments
CAD – CAM method
Design criteria
l  The abutment design on the right is of concern because of
subgingival cement accumulations may be difficult to access
and remove
Anatomic form/contour No tissue displacement
Support contoured
soft tissue

Custom abutments
CAD – CAM method
Materialsl  Titanium
l  Zirconia
l  Chrome - cobalt
Zirconia is not recommended in the posterior quadrants because of
the risk of fracture (Canullo et al, 2013; Sghaireen, 2013)

❖  The treatment procedure is similar to current methods
Shape memory
sleeve abutment system

”
‣  Nitinol is safe and bio-compatible
‣ Many devices are approved by FDA
‣  Economical to manufacture
Arch bars
Heart balloon
Heart stent
(Nickel titanium alloy)
Shape memory

Shape memory
l  The flaps of the sleeve engage the abutment and
the out flaps engage coping of the implant crown

Shape memory

Shape memory
l  The crown can be removed by
transmitting an electric current
through the coping and into
the shape memory sleeve

Provisional restorations
l  Used to resolve issues regarding esthetics,
occlusal scheme, and prosthetic design.
l  The posterior teeth on both sides of the
arch are restored with implans

Provisional restorations milled from PMMA
and designed with CAD programs
Provisional can be designed and milled with CAD-CAM
programs. This prototype was milled from a block of PMMA.
Courtesy Dr. M. Moscovitch

Impressions
l  Transfer copings with closed tray for linear
configurations
Fabricating the
definitive restorations

Fabricating the
l  Make records and mount casts
l  Transfer records to the articulator

Fabricating the
Virtual articulation and design programs

Fabricating the
definitive restorations - Occlusal factors
l  Narrow the occlusal table
l  Buccalize or lingualize as
required
l  Centric only contacts

Fabricating the
definitive restorations – Hygiene access
l  Smooth emergence profiles
l  Proxy brush access

Fabricating the
definitive restorations – Pontic design
l  No ridge laps
l  Modified ridge lap pontic designs are
favored in the posterior quadrants

Fabricating the
Custom abutment designs – Cement retained
l  Avoid abrupt changes in contour
at the margin of the restoration
l  Place margins slightly supra-
gingival

Fabricating the
definitive restorations – Occlusal materials
l  Occlusal forces delivered into the bone anchoring
the implants are not effected by the nature of the
occlusal material (Gracis et al, 1991)
Metal Laminated porcelain Monolithic zirconia

Fabricating the
Metal Laminated porcelain Monolithic zirconia
Criteria for selection based upon:
Wear characteristics
Nature of the dentition in the opposing arch
Potential for failure
Esthetics
Parafunctional activity

l  Preferred
Fabricating the

Fabricating the
Laminated Porcelain
Issues
l  Fracture and chip rate has been
reported as high as 22% when
the framework is made of
zirconia (Nothdurft et al, 2013)

Fabricating the
Monolithic zirconia
l  PMMA prototype adjusted
l  Scanned
l  Fabricated in zirconia
l  Initial data is promising but short
term (Moscovitch, 2015)
Courtesy Dr. M. Moscovitch

Fabricating the
definitive restorations – Try in
l  A jig designed to
correctly orient
multiple abutments
made of metal

Fabricating the
definitive restorations – Try in
l  A jig designed to
correctly orient multiple
abutments made of
pattern resin

Fabricating the
definitive restorations - Delivery
l  Occlusal adjustment
l  Two thicknesses of mylar should pass through the
implant contact when the natural teeth hold one
thickness
l  Proximal adjustments
l  Two thicknesses of mylar

Note: The cusp
angles are flat
and the occlusal
tables are
narrow
Result: Lateral
forces on the
implants are
minimized
Anterior group
function with centric only contact

Group function
Patient in right working position.
Note lateral guidance is provided
by the premolars and the central
incisor.
Result: Lateral forces
on the implants are
minimized. Courtesy Dr. M. Hamada

Anterior (canine) Guidance
Space allowed only two implants to be placed in
this patient. However, note anterior guidance.
Design the occlusion to minimize the delivery of nonaxial forces
Courtesy Dr. M. Hamada

Group function
•  Only two implants have been placed to restore the corner of
the arch in this patient.
•  The implants were inclined towards the labial and milled
customized abutments were used.
•  Note that the minimal height of the buccal wall of the posterior
abutment. As a result retention was designed to be achieved
with lingual set screws as opposed to cement.

Group function
•  The finished prosthesis.
•  It is adjusted so that contact during lateral excursion is
provided by the natural dentition and not the implants.

Restoring the corner of the arch :
Mutually protected occlusion
Group function
was used to
distribute lateral
loads as widely as
possible in order
to reduce the risk
of implant
overload

Cement
retained restorationsIssues
l  Retention and resistance form of the custom abutment
l  Retention of cement subgingivally leading to peri-implantitis and in
some cases loss of the implants and adjacent teeth
l  80% of all cases of peri-implantitis are associated with retained cement

Cement
retained restorations
v  What are the risks of impacting cement
subgingivally?
v  It depends on the position of the margin. In a recent
study if the margin was as little as one mm subgingivally,
the rate was 100% (Linkevicius et al, 2013)
v  Even if the cement is detected it is difficult to remove
without reflecting a flap
v  Of these what percentage of patients develop peri-
implantitis?
v  Unknown

Subgingival cement accumulation
Prepable abutment
v The abutment is prepared so that the margin is slightly sub gingival.
v An impression is made and the porcelain fused to metal crown was
completed in a customary fashion.
v The abutment is secured to the implant fixture and the crown is then
cemented.

Prepable abutment
v The patient was unhappy with the esthetic result and so a
hole was drilled into the occlusal surface in order to access the
abutment screw. The crown and abutment was then removed
v Note the accumulation of cement subgingivally.

Cement
Problem
l  Most dentists are not familiar with
the proper technique to cement an
implant crown given the fragility of
the epithelial attachment
l  They attempt to use the same
method they use with natural
dentition (Wadhwani et al, 2012)
Courtesy Dr. C. Wadhani

ImplantSurface
Bone
EpitheliumSulcus
Circumferential
collagen fibers
*
Peri-implant
tissues are
more easily
displaced from
the surface of
the implant
crown implant.
Why is there a greater risk of
cement accumulation in the
sulcus of implant crowns?

Cement
Strategies to limit embedding cement subgingivally
l  Avoid the use of stock (prefabricated abutments
l  Proper design of the custom abutment
l  Place the crown margin at or above the gingival margin
l  Venting ????
l  Packing retraction cord prior to cementation ?????
l  Avoid the use of an excessive amount of cement

Strategies to limit
embedding cement subgingivally
Avoid the use of stock (prefabricated) abutments
Considerations for use:
v Tissue height should be essentially the same, 360
degrees around the abutment
v Occlusal clearance for sufficient axial wall height for proper
resistance and retention form
v Angulation allows reasonable draw with adjacent teeth

Strategies to limit
v Use custom abutments
v Place the margins supra-gingivally

Strategies to limit
Venting the restoration
This is not an effective strategy. Venting helps the clinician
seat the restoration but if the margin is subgingival cement is
still injected deep into the sulcus (Wadhwani et al, 2012).

Strategies to limit
Venting the abutment (Wadhwani et al, 2011)
v  Vent holes are placed 180
degrees from one another on
the abutment above the level
of the abutment screw head
v  With this design the excess
cement flows into the
chamber above the head of
the abutment screw
v  Shows promise with bench
studies
Courtesy Dr. C. Wadhani

Strategies to limit
Packing retraction cord into the cord prior to
cementation
§  Gives the clinician a
false sense of security
§  If the margin is sub-
gingival, cement is still
extruded sub-gingivally
and often apical to the
retraction cord

Strategies to limit
Best strategy
v  Supra-gingival margins
v  Controlling the amount of cement used
v  Line the implant crown/s with teflon tape. The thickness of the tape mimics
the thickness of the film thickness of the cement
v  Inject a fast set vinyl polysiloxane material into the intaglio surface of the
crown. This will form a duplicate of the abutment
v  Remove the polysiloxane abutment duplicate and the teflon tape
v  Coat the inner surfaces of the implant crown/s with cement, seat the
silicone abutment duplicate, remove the excess cement and seat the
prosthesis into position intra-orally Courtesy Dr. C. Wadhani

Types of cements used
v  Polycarboxylate cements should not be used because
they contain fluoride which will corrode the titanium
surface of the implant or abutment.
v  Resin cements containing hydroxylated ethymethacrylate
(HEMA) which is potent cytotoxic agent, should be
avoided.
v  Zinc oxide and eugenol cements are favored. The are
anti-bacterial and are radio-opaque.

Complications and trouble shooting
Mechanical failures: Screw loosening
v  Rare with abutment size screws of modern
designs and when they are tightened
sequentially and with proper torque
v  More frequent with prosthetic size screws
v  These screws are of smaller diameter, finer thread
patterns and are tightened to only 10-15 N/cm
v  We prefer not to use prefabricated (stock) abutments
because the prosthesis is retained with these small
screws

Mechanical failures: Screw fracture
v  Rare with abutment size screws of modern designs
v  More frequent with prosthetic sized screws
v  These screws are of smaller diameter
Removal can be accomplished with an explore or a scaler. Some-
times it helps to rotate the screw fragment deeper into the implant
and then smooth over irregularities of the threads of the implant by
means of a tap, or an impression coping etc. Courtesy Dr. N. AbouJaoude

Mechanical failures: Screw fracture
Sometimes the internal
threads of the implant must
be retapped. A guide
sleeve is useful when
attempting this maneuver
Guide
sleeve
Tap
Courtesy Dr. N. AbouJaoude

v  Usually seen in implants with unfavorable
configurations, alignments and patients
exhibiting parafunctional activity.
v  Note the unfavorable ratio between the
length of the implants and the distance to
the occlusal surfaces.
Mechanical failures: Implant fracture
(Courtesy Dr. N. AbouJaoude)

Unfavorable configurations, alignments and
patients exhibiting parafunctional activity.
Patient presents with:
l  Unfavorable ratios between the lengths of the implants
and the distance to the occlusal plane,
l  Poor anchorage in grafted bone
l  Palatally positioned implants inclineed towards the buccal
l  A linear configuration
Courtesy Dr. TL Chang

Design
l  Implant-assisted overlay RPD
l  Implants used for support and
retention
l  Bracing (resistance to lateral
forces) supplemented by the RPD
design
Unfavorable configurations, alignments
Hader bar
attachment
ERA
attachment
Axis of
rotation

l  Implant connecting bar design is
implant-assisted
l  Cross arch stabilization provided by
the RPD design protects the
implants from potentially detrimental
lateral forces
Unfavorable
configurations, alignments

This is a five year followup x-ray
of a patient with an implant
supported fixed partial denture.
Closer exam revealed
both implants to be
fractured .
The patient was a heavy bruxer.
Six months later he presented
with significant bone loss around
both implants.

This patient did well with this implant
supported fixed partial denture for more
than four years (note 4 year followup x-ray).
However, soon thereafter, the anterior
implant fractured, the bridge was
removed and a trephine used to
remove the implant.

The neck of this implant fractured during placement.
Courtesy Dr. T. Tang

Fractured abutments
•  Rare except for zirconia
abutments.
•  When they facture those with
an internal connection are
often difficult and time
consuming to remove
Courtesy Dr. A. Sharma

§  Peri-implant mucositis:
§  A reversible inflammation of the soft tissues
surrounding implants in function
§  Incidence:
§  Up to 38% of implants (Mir-Mari et al, 2012)
§  Treatment:
§  Removal of offending irritants (plaque, calculus,
cement etc.
§  Local anti-microbial agents (Arestin, Atridox)
(Trejo et al, 2006; Heitz-Mayfield et al, 2011).

•  Peri-implantitis:
•  An inflammatory process affecting the tissues around and
osseointegrated implant in function, resulting is loss of supporting bone
Signs and symptoms
v Bleeding upon probing
v Granulation tissue formation
v Purulence
v Bone loss around the implants

Risk factors
•  Periodontitis
•  Smoking
•  Diabetes
•  Subgingival cement accumulations (80%
according to Wilson et al, 2000)
•  Loose retaining screws

Incidence
§  Unknown primarily because of
imprecise definitions used in
the literature, multiple factors
causing bone loss, etc.

l  Peri-implantitis –
an enigma. What
is it really?
Treatment
l  Usual conservative therapies
l  Removal of plaque, calculus,
subgingival cement accumulations,
chlorhexidine mouth rinses, and in
nonresponders systemic antibiotics
such as metronidazole and
amoxicillin.
l  Plus instructions to check the
occlusion for excursive contacts,
loose screws, presence of
foreign bodies, etc
Courtesy Dr. D. Krill

l  There is no evidence to indicate that bony reconstruction are
successful or have any impact on treatment outcomes.
Courtesy Dr. D. Krill

l  Surgical debridement is recommended by some periodontists
l  Flaps are reflected to allow removal of retained cement, and
decontamination of the implant surface
l  Some have attempted to reconstruct the bony defects with
bone grafts
l  There is no evidence that this approach improves clinical
outcomes

l  According to one study, 80% of peri-implantitis cases are
directly associated with retention of cement subgingivally

l  Loss of keratinized tissue
l  Problematic around mandibular molars
l  Ounce of prevention is worth a pound of cure.
Encourage the use of mucosal repositioning flaps during
initial implant placement or during second stage surgery.

Recurrent loss of retention – cemented restorations
l  Insufficient height of axial walls can be due to:
l  Buccal or lingual inclinations
l  Lack of interocclusal space
Secondary to
inadequate retention
and resistance form

Chipping and fracture of the laminated porcelain
l  Up to 22 % when the framework is zirconia
l  8-10% when the framework is a ceramo-metal

Case report
l  This 49 year old, healthy female presented with multiple tooth loss in
the posterior maxilla and wished to have these teeth replaced,
preferably with implants. Loss of these teeth was secondary both to
caries and periodontal disease. The mandibular dentition was mostly
intact, but there were abnormalities in the occlusal plane in the molar
region because of wear, super-eruption of molar teeth and
unfavorable crown contours. The remaining maxillary posterior tooth
exhibited advanced peridontal bone loss, with deep peridontal
pockets and was clinically mobile. There was an impacted 3rd
maxillary molar on the right side. There was no evidence or
indication of parafunctional activity. The mandibular dentition was in
good condition with minimal periodontal bone loss. Several crowns
restoring the mandiblular molars had open margins but only minimal
caries was noted. The maxillary sinuses exhibited varying degrees
of pneumatization with insufficient bone to anchor implants (6-8 mm
on the right and 3-8 mm on the left). The anterior maxillary and
mandibular teeth were in good condition with significant vertical
overlap and anterior guidance

Case report
Major issues considered in this patient
l  Implant supported FDP vs. RPD
l  Socket augmentation
l  Sinus augmentation
l  Number and arrangement of implants
l  Screw retained vs cement retained
prostheses
l  Do I need provisional restorations
l  Splinting vs nonsplinting
l  Occlusion – Anterior group function vs. group
function

Case report
l  Provisional restorations

Case report
l  Custom abutments
l  Definitive
restorations

Case report
l  Occlusion – Anterior group function
l  Patient is 15 years post delivery with
virtually no loss of marginal bone
l  No chipping or fractures of porcelain

Case report
This 71 year old healthy male presented with a failing fixed partial denture in the mandibular
left posterior quadrant. The patient wished to replace these teeth with a fixed prosthesis. The
fixed partial denture was failing, most probably because of the the extended span and the ratio
of the number of dental units restored (5) in relation to the number of natural tooth abutments
available (2) was unfavorable. The anterior abutment had fractured, probably due to the
length of the span, and this tooth was nonrestorable. The maxillary arch was partially
edentulous and several existing crowns exhibited caries at the margins. Teeth #15 and #29
had a questionable prognosis. The maxillary dentition exhbited little periodontal compromise
but minimal pockets were found associated with the teeth of the posterior right quadrant. The
discrepancies associated with the plane of occlusion were not clinically significant, but crown
contours of the maxillary teeth were unfavorable. The posterior maxillary teeth on the left side
were slightly extruded. Wear was moderate and there was evidence of parafunctional activity
(bruxism). Oral hygiene was unsatisfactory. The posterior molar in the left mandible was tipped
mesially and was unsuitable as an abutment for a fixed partial denture. However, it was
periodontally sound and could be retained as an RPD abutment if the patient wished to pursue
this form of treatment. The patient’s terminal dentition on the right side extended to the first
molar. Exam revealed minimal bone loss of the edentulous segment in the left posterior
mandible. The mandibular anterior teeth were crowded and exhibited root proximity.
However, these teeth were positioned such that an anterior guided, mutually protected
occlusal scheme was present and consistent with the patient’s envelope of function.
Consequently, the patient did not wish to correct the arrangement of these teeth strictly for
esthetic purposes.

Case report
Issues considered in this case
l  Implant supported fixed dental prostheses vs
removable partial denture (RPD)
l  Number and arrangement of implants
l  Cement retained vs screw retained prostheses
l  Cement retained vs screw retained prostheses
l  Occlusal materials
l  Occlusion – Anterior group function vs group
function

Case report
l  Surgical drill (template) guide

Case report
l  Cement retention with custom abutments

Case report
l  Definitive restoration

Case report
l  Definitive restoration
l  Note the hygiene access

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Implant Dentistry, Removable
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Dentistry and Maxillofacial
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Prosthodontics Procedures and Complications - Posterior Quadrants

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