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1. Bridge Failures
“Technology in the hands of a skilled operator makes it possible
to do more work of an even higher quality. But in the hands of one
who has not mastered the skills of his or her profession, that
technology merely enables one to do tremendous damage.”
-
Herbert T. Shillingburg
Excellence in dental care is achieved through the dentist’s ability to
assess the patient, determine needs, design an appropriate treatment
plan and execute the plan with proficiency.
CLASSIFICATIONS
The causes of FPD failures were summarized as early as in 1920 when Tinker
wrote
“Chief among the causes for such disappointing results has been:
First: Faulty, and in some cases, no attempt at diagnosis and prognosis.
Second: Failure to remove foci of infection in attention to treatment and care of the
investing tissues and mouth sanitation.
Third: Disregard for tooth form
Fourth: Absence of proper embrasures
Fifth: Inter proximal spaces
Sixth: Faulty occlusion and articulation

2. Other classification given by Bennard G. N. Smith
1. Loss of retention
2. Mechanical failure of crowns or bridge components
a. Porcelain fracture
b. Failure of solder joints
c. Distortion
d. Occlusal wear and perforation
e. Lost facings
3. Changes in the abutment tooth
a. Periodontal disease
b. Problems with the pulp
c. Caries
d. Fracture of the prepared natural crown or root
e. Movement of the tooth
4. Design failures
a. Under-prescribed FPDs
b. Over-prescribed FPDs
5. Inadequate clinical or laboratory technique
a. Positive ledge
b. Negative ledge
c. Defect
d. Poor shape and color
6. Occlusal problems

3. Failures of FPD
Failures of fixed partial dentures occur based on:
• Patient complaints
• Duration of time
Patient complaints
• Pain
• Sensitivity
• Looseness of bridge
• Pain in soft tissue (gingiva)
• Esthetics
• Fracture
• Swelling
• Speech
• Mastication
Duration of time
• Immediate
• Delayed
TYPES OF BRIDGE FAILURES
I.
Cementation failure
II.
Mechanical failure
III.
Gingival and periodontal breakdown
IV.
Caries
V.
Necrosis of pulp
VI.
Esthetic failure

4. I.CEMENTATION FAILURE
• Cement failure
• Retention failure
• Occlusal problems
• Distortion of the bridge
Cement Failure
• Cement selection
• Old cement
• Prolonged mixing time
• Thin mix
• Thick mix
• Cement setting prior to seating
• Inadequate isolation
• Incomplete removal of temporary cement
• Thick cement space
• Inclusion of cotton fibers
• Insufficient pressure while cementation

5. Cement Selection
• FPD Multiretainers - GIC
• Non Vital Teeth/Advanced Pulp Recession - ZINC PHOSPHATE
• Temporary Cementation - ZINC OXIDE EUGENOL
• Fixation of Facings- DIMETHACRYLATE COMPOSITES
• Abutment with Minimal Dentin / Exposure - CALCIUM HYDRO
OXIDE + ZINC OXIDE EUGENOL
Thick Cement Space
• Convergence below 6º
• Excessive application of die spacer
• Thick cement mix
• Grinding metal inside retainers
• Cement setting prior to seating
How to Confirm Cement Failure
 Pull the crown margin and see for movement of the crown
 Crown margins which were subgingivally placed will be visible
when we pull the crown margin

6.  Bubbles come out of the margin or through perforation of the crown
(if present) when the crown margin is pushed by applying pressure
occlusally
Retention failure
• Excessive taper
• Short clinical crown
• Mis-fit
• Mis-alignment
Retention
• Retention prevents the removal of the restoration along the path of
insertion or the long axis of the tooth.
• Resistance prevents dislodgement of the restoration by forces
directed in apical or oblique direction
Improving Retention
• Additional retentive grooves/ proximal grooves.
• Additional pins- drill the retainer & tooth .5 to .7 mm with round
bur in buccal & lingual aspects, cut the excessive length & smoothen

7. the area.
• Crown lengthening
• Sub gingival margins
• Additional abutments
Excessive Taper
• The relationship of one wall of preparation to the long axis of that
preparation is the inclination of that wall.
• Sum of the inclination of two opposing walls give the taper of the
preparation.
• Minimum 12º taper is necessary to ensure the absence of undercuts
& also the restoration is placed on the preparation after being
fabricated in final form.
• Conscious effort to incorporate taper usually results in over tapered,
non retentive preparation.
Short Clinical Crown
• Cement creates a weak bond, largely by mechanical interlocks,
between the inner surface of the restoration & the axial wall of the
preparation. So, greater the surface area of preparation, greater wills

8. the retention.
• A short, over tapered crown would have minimal ret ention because
the restoration can be removed along infinite paths.
• Because the length of axial wall occlusal to finish line interferes
with the displacement, the length & inclination become important
factors.
Misfit
Causes
• Expansion of metal substructure because of
-Improper water /powder ratio of investment
-Improper mixing time
-Improper burn out temperature
• Distortion of the margins
• Distortion of metal substructure
• Metal bubbles in occlusal or margin regions because of
- Inadequate vacuum during investing
- Improper brush technique
-
No surfactant
• Porcelain inside retainer

9. • Excessive oxide layer in inner side of retainer
• Tight contact points
• Thick cement space
• Insufficient pressure during cementation
Misalignment
• In case of misalignment the bridge will +ve spring in it & tend to
seat further on pressure due to abutment teeth moving slightly
• In misfit the resistance felt is solid.
Causes
• Abutment displacement due to improper temporization.
• Distortion of wax pattern
• Casting defects
• Distortion of metal framework in porcelain firing.
• Porcelain flow inside the retainers
• Mal alignment of solder joints
• Excessive metal or porcelain in tissue surface of pontic.
Remedy
• If the bridge seats fully under pressure - leave it in place for 30 min
to 1 hr asking the patient to exert gentle pressure.

10. • If it does not work, temporarily cement to one of the retainers for 1
to 2 days.
• Then, the bridge is unsoldered, separate components tried. If they
seat, take location impression & resolder.
Occlusal problems
Problems in occlusion are basically
Immediate problems
1. Occlusal interferences
2. Marginal ridges at different levels
3. Supra eruption of opposing tooth
4. Para functional habits
Delayed problems
1. Wearing of occlusal surfaces
2. Loss of occlusal contacts
3. Cementation failure due to lateral forces
4. Periodontal and gingival breakdown
5. Tenderness
Torque
• From a cusp extended too far bucally or lingually.
• Pre mature contact on lateral excursion extremity.

11. • Results in cementation failure.
Reduce bucco lingual width of occlusal surface
Indications
• Mobility of teeth
• Tenderness on mastication
• Hyperemia of soft tissues
• Sensitivity to heat, cold & sweet
• Burnished metal in area of premature contact
Checking occlusion
Touch
Tin articulating paper
Occlusal indicator wax
Occlusion should be adjusted both in centric and eccentric
Distortion
• Distortion of wax patterns
• Incomplete casting

12. • Long span bridges
Wax Patterns
• Removal from the die
• Spruing stage
• Investing stage because of the thick investment material.
Incomplete Casting
• Too thin wax patterns
• Incomplete wax elimination
• Cool mold or melt
• Insufficient metal
Long Span Bridges
• Thin crown
• Soft metal
• Heat treatment not being done
• Porosity in the metal
• Distortion of margins.

13. MECHANICAL FAILURE
1. Retainer failure
2. Pontic failure
3. Connector failure
Retainer Failure
Perforation
• Insufficient occlusal reduction
• High points in opposing dentition
• Premature contacts
• Soft metal
• Porosity
• Para functional habits
Marginal Discrepancy
The more accurately the restoration is adapted to tooth, the less
will be chances of cementation failure, recurrent caries or periodontal
disease. 50μ to 100μ discrepancy is acceptable.
• Rough margins reduce adaptation
• Open margins encourage entry of saliva and cariogenic organisms
• Over extended margins cannot be adapted to converging convexity
of tooth at cervical margin

14. Causes
• Selection of margin
• Improper preparation
• No gingival retraction
• Improper selection of impression materi al
• Distortion of wax patterns
• Nodules at margin or inside casting
• Thick cement
• Prior setting of cement
Facing Failure
Fracture
Too little retention
Spot contact at porcelain metal junction
Malocclusion
Microleakage.
Wearing

15. • Deep bite
• Acrylic veneering opposing porcelain teeth
• Faulty brushing & flossing
• Parafunctional habits
Discoloration
• Absorption of oral fluids
• Absorption
of
artificial
food
colouring
agents
through
the
microcracks or microleakage in metal & facing
• Tarnish of underlying metal & facing
Pontic failure
Requirements
F o r m & s h a p e o f g i n g i v al s u r f a c e mu s t n o t i r r i t a t e r e s i d u a l r i d g e
Design must incorporate mechanical principles for strength &
longevity
Esthetics
Residual Ridge Contour
• Ideal - smooth, easy to clean
• Irregular hyperplastic tissue (commonly because of an ill fitting rpd)

16. must be surgically removed
• Severe bone resorption (particularly because of trauma) - surgical
ridge augmentation
Ridge Contact
• Pressure free contact without blanching.
• In esthetic zone, the pontic should contact on the labial/ buccal
aspect.
• In mandibular posteriors hygienic pontic can be given.
Metal Sub Structure is compromised due to
• Limited edentulous space in Occluso gingival direction due to supra
eruption of opposing tooth.
• Limited space mesiodistally due to drifting of adjacent teeth
• Framework must provide uniform thickness for porcelain - cut back
wax uniformly
Metal ceramic junction should be 1.5 mm away fr om junction.
GINGIVAL AND PERIODONTAL BREAKDOWN
- Margins placement
- Integrity of contacts and margins
- Occlusion

17. Reasons for gingival breakdown
•
•
•
•
•
•
Plaque retention
Improper design
Faulty margins
Incorrect occlusal anatomy
Over contoured retainer
Inadequate embrasure
Treatment options:
• Give proper oral hygiene instructions
• Remake the bridge
Reasons for periodontal breakdown:
• General periodontal problems
• Local periodontal problems like
- Poor bridge design
- Incorrect assessment of abutment strength
- Insufficient abutment selected
- Traumatic occlusion
Treatment options:
• Remake the bridge
Supra Gingival Margins
Advantages
• Can be easily finished
• Easily cleanable
• Impressions easily recordable
• Easy evaluation at recall

18. Disadvantages
• Esthetically inferior
• Not indicated for short clinical crowns
• Not indicated in case of root sensitivity
Sub Gingival Margins
Indications
• Esthetic demands
• Caries removal
• Existing sub gingival restorations
• Crown lengthening.
Disadvantages
• Difficult to prepare
• Soft tissue prone to trauma
• Causes gingival & periodontal pathosis
• Difficult oral hygiene
• Metal margins seen through gingival.

19. CARIES
• Caries occouring on the margin of the retainer,
• Caries affecting indirectly by starting elsewhere on the tooth and
spreading.
• Caries due to cementation failure.
Reasons for caries:
• Poor oral hygiene
• Open margins
• Faulty contacts
Treatment options:
• Use conventional filling materials
• Correction of crowns and bridges if possible
• Remake the bridge
NECROSIS OF PULP
Can occour at three stages
- Prior to preparation
- During preparation
- After preparation

20. Reasons for pulp necrosis:
• Increased occlusal trauma
• Increased heat during preparation
• No pulp protection
Other reasons for pulp necrosis:
• Speed, size, and type of the rotating instrument
• The amount of pressure used
• Depth of remaining dentin
• Vibration
• Coolants
• Desiccation
• Chemical injury
Treat ment options:
• For anterior teeth – apicecto my and retrograde filling
• For posterior teeth – endodontic therapy
• R e ma k e t h e b r i d g e
ESTHETIC FAILURES
Requirements for Esthetic Restorations
Proper shade selection
Correct tooth preparation
Avoidance of grey margins
Prevention of metal exposure
Final impression

21. Reasons for Esthetic Failure
• Failure to identify patient expectations regarding esthetics
• Improper shade selection
• Failure to transfer shade selection to laboratory
• Excessive metal thickness at incisal and ce rvical regions
• Over glaze or too much smooth surface
• Metal exposure in connector, cervical, and incisal region
• Dark space in cervical third due to improper pontic selection
(anteriors)
• Failed to produce incisal and proximal translucency
• Improper contouring
• Failure to harmonize contra-lateral tooth morphology- contour,
colour, position, angulations
• Discoloration of facing
Shade Selection
• Walls and surroundings should be in neutral colour or blue
• Never select under direct sunlight
• Upright position of the patient
• Use squint test
• Teeth should be clean and unstained

22. • Shade selection should be done before teeth preparation
• Don’t dry the tooth while selecting the shade
• Canine is the darkest tooth
• Premolars lighter shade than canine
• Maxillary anteriors are missing, shade of the mandibular anteriors is
considered
• In case of a non-vital tooth, cover it and select the shade of the
adjacent tooth.
Other Biologic bridge failure are
Fracture of tooth
Reasons for fracture:
• Improper abutment selection
• Wear of tooth
• Increased occlusal forces
Treatment options:
• Remake the bridge using more abutment teeth.
Temporo-mandibular joint problems

23. R e a s o n s f o r TM J p r o b l e ms :
• I mp r o p e r o c c l u s a l s c h e me
Treat ment options:
• R e ma k e t h e b r i d g e u s i n g p r o p e r o c c lu s a l s c h e me
Caries… the frequent culprit
Caries – 38%
Periapical involvement – 15%
Perforated occlusal surface – 10%
Fracture post &core – 8%
Defective margins – 8%
Fracture teeth – 7%
Porcelian failures – 8%
JPD, Vol 78, Issue 2, pg 127-131, Aug 1997

24. Conclusion
Failures most often occur because of violation of principles either
collectively or individually and for the most part are due to attempted
short-cuts or positive indifference and inexcusable ignorance on the
part of those concerned. Whatever said and done, at last it is only the
ability of a Prosthodontist which determines the success or failure of a
fixed partial denture.

25. Bibliography
• Shillingburg HT, Hobo S, Whitsett LD, Jacobe R, and Brackett SE:
Fundamentals of fixed prosthodontics, ed. 3, Chicago, 2001, Quintessence,
Inc.
• Tylman’s theory and practice of fixed Prosthodontics,8th edi,1989,William
F.P.Malone, David .L.Koth
• Roberts DH: Fixed bridge prosthesis, ed. 1, Bristol, 1973, John Wright &
Sons.
• Rosenstiel SF, Land MF and Fujimoto J: Contemporary fixed
prosthodontics, 2001, ed. 3, N.Delhi, Harcourt.
• Longevity of fixed partial dentures,JPD,Vol 78,Issue 2,Pg 127-131,Aug
1997.
• Failures related to crown and fixed partial dentures fabricated in Nigerian
dental school, Journal of contemporary dental practise, Vol 6, No 4,Nov
15,2005.
• Clinical complications in fixed Prosthodontics, JPD,2003,90 Vol, pg 31-41

26. A seminar on
Failures in fpd
Presented by
Dr.G.MANMOHAN,
Final year P.G Student,
Date: 12-07-08.
Signature of Prof & HOD
SIBAR INSTITUTE OF DENTAL SCIENCES
Guntur-522509