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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:

Fpd failures/certified fixed orthodontic courses by Indian dental academy

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Page 1: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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

Page 2: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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

Page 3: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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

Page 4: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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

Cement Selection

Page 5: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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

Bubbles come out of the margin or through perforation of the crown

(if present) when the crown margin is pushed by applying pressure

Page 6: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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

the area.

• Crown lengthening

• Sub gingival margins

Page 7: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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

the retention.

• A short, over tapered crown would have minimal retention because

the restoration can be removed along infinite paths.

Page 8: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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

• Excessive oxide layer in inner side of retainer

• Tight contact points

• Thick cement space

Page 9: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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.

• 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.

Page 10: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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.

• Results in cementation failure.

Reduce bucco lingual width of occlusal surface

Indications

• Mobility of teeth

• Tenderness on mastication

Page 11: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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

• Long span bridges

Wax Patterns

• Removal from the die

• Spruing stage

• Investing stage because of the thick investment material.

Incomplete Casting

Page 12: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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.

MECHANICAL FAILURE

1. Retainer failure

2. Pontic failure

3. Connector failure

Retainer Failure

Perforation

• Insufficient occlusal reduction

Page 13: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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

Causes

• Selection of margin

• Improper preparation

• No gingival retraction

• Improper selection of impression material

• Distortion of wax patterns

• Nodules at margin or inside casting

Page 14: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• Thick cement

• Prior setting of cement

Facing Failure

Fracture

Too little retention

Spot contact at porcelain metal junction

Malocclusion

Microleakage.

Wearing

• 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

Page 15: Fpd failures/certified fixed orthodontic courses by Indian dental academy

microcracks or microleakage in metal & facing

• Tarnish of underlying metal & facing

Pontic failure

Requirements

Form & shape of gingival surface must not irritate residual ridgeForm & shape of gingival surface must not irritate residual ridge

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)

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.

Page 16: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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 from junction.

GINGIVAL AND PERIODONTAL BREAKDOWN

- Margins placement- Integrity of contacts and margins- Occlusion

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

Page 17: Fpd failures/certified fixed orthodontic courses by Indian dental academy

- 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

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.

Page 18: Fpd failures/certified fixed orthodontic courses by Indian dental academy

Disadvantages

• Difficult to prepare

• Soft tissue prone to trauma

• Causes gingival & periodontal pathosis

• Difficult oral hygiene

• Metal margins seen through gingival.

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

Page 19: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• Remake the bridge

NECROSIS OF PULP

Can occour at three stages - Prior to preparation

- During preparation

- After preparationReasons 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

Treatment options:Treatment options:

•• For anterior teeth – apicectomy and retrograde fillingFor anterior teeth – apicectomy and retrograde filling

•• For posterior teeth – endodontic therapyFor posterior teeth – endodontic therapy

Page 20: Fpd failures/certified fixed orthodontic courses by Indian dental academy

•• Remake the bridgeRemake the bridge

ESTHETIC FAILURES

Requirements for Esthetic Restorations

Proper shade selection

Correct tooth preparation

Avoidance of grey margins

Prevention of metal exposure

Final impression

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 cervical 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

Page 21: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• 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

• 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:

Page 22: Fpd failures/certified fixed orthodontic courses by Indian dental academy

• Improper abutment selection• Wear of tooth• Increased occlusal forces

Treatment options: • Remake the bridge using more abutment teeth.

Temporo-mandibular joint problems

Reasons for TMJ problems:Reasons for TMJ problems:

•• Improper occlusal schemeImproper occlusal scheme

Treatment options:Treatment options:

•• Remake the bridge using proper occlusal schemeRemake the bridge using proper occlusal scheme

Caries… the frequent culprit

Caries – 38%Caries – 38%

Periapical involvement – 15%Periapical involvement – 15%

Perforated occlusal surface – 10%Perforated occlusal surface – 10%

Fracture post &core – 8%Fracture post &core – 8%

Defective margins – 8%Defective margins – 8%

Fracture teeth – 7%Fracture teeth – 7%

Porcelian failures – 8%Porcelian failures – 8%

Page 23: Fpd failures/certified fixed orthodontic courses by Indian dental academy

JPD, Vol 78, Issue 2, pg 127-131, Aug 1997 JPD, Vol 78, Issue 2, pg 127-131, Aug 1997

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.

Page 24: Fpd failures/certified fixed orthodontic courses by Indian dental academy

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

Page 25: Fpd failures/certified fixed orthodontic courses by Indian dental academy

A seminar on

Failures in fpd

Presented by

Dr.G.MANMOHAN,Final year P.G Student,Date: 12-07-08. Signature of Prof & HOD

Page 26: Fpd failures/certified fixed orthodontic courses by Indian dental academy

SIBAR INSTITUTE OF DENTAL SCIENCES Guntur-522509