FAILURES IN FIXED PARTIAL DENTURES

FAILURES IN FIXED PARTIAL DENTURES
DEPARTMENT OF PROSTHODONTICS
3rd Year Resident

CONTENTS
Introduction
Classification
Review Of Literature
Causes of failure in FPD
Biological failures
Mechanical failures
Esthetic failures
Causes & management
Conclusion
References

INTRODUCTION
• Fixed prosthodontic treatment can offer exceptional satisfaction for both patient and dentist. It
can transform an unhealthy, unattractive dentition with poor function into a comfortable,
healthy occlusion capable of giving years of further service while greatly enhancing esthetics.
• To achieve such success, however, requires meticulous attention to every detail from initial
patient interview, through the active treatment phase, to a planned schedule of follow-up care.

• Fixed prosthodontic failures can be frustrating and complex in terms of both
diagnosis and treatment and may occur at any time. Hence, it is important to be
aware of obvious and subtle indications of prosthesis failure and have a working
knowledge of the procedure that are necessary to remember the situation.

• Before calling any fixed tooth-supported prosthesis as “Failing” or “Failed” ,
there are certain objectives which a fixed prosthesis should fulfill.
• Failing to fulfill these objectives leads to failures in fixed prosthodontic
treatment.

• Gerson (1957) – stated that inadequately cemented restorations may cause an increased
vertical dimension, loosening of the crown or FPD after a relatively short time,
microleakage and decay under the abutments, exposure of metal margins and sensitivity.
• Leonard I. Linkow (1962) – gave the importance of form, type, shape and position of
contact areas. He stated that the contacts which are flat, open, improperly placed, rough,
or poorly polished will lead to displacement of teeth and exert a lifting force, disturb the
axial relationship, injure supporting tissues, produce a deflective occlusal contact and
vertical or horizontal food impaction.

• Fifty patients - 89 FPDs.
• Of the 89 FPDs, 13 or 15%, were identified as failures or had been replaced because of failure.
• Dental caries (38%)
• Perforated occlusal surfaces (15%)
• Fractured post and cores (8%)
• Defective margins (8%)
• Fractured teeth (7%)
• Porcelain failures (8%).
Libby .G et al, Longevity of fixed partial dentures, J Prosthet Dent. 1997
Aug;78(2):127-31

• For the aggregate population represented by the limited longitudinal studies available,
this meta-analysis indicated that:
• Less than 15% of fixed partial dentures were removed or in need of replacement at 10
years;
• whereas, nearly one third were removed or in need of replacement at 15 years.
• Less than 5% of abutments were removed at 10 years.
MarkScurria,James Bader : Meta-analysis of fixed partial denture survival:
Prostheses and abutments (J Prosthet Dent 1998;79:459-64.)

• The aim of this study was to evaluate the factors that influence the longevity of fixed
metal ceramic bridge prostheses, including the length of the bridge as well as the basic
circumstances of the mouth.
• A total of 132 patients attended the clinical examination- altogether 195 bridges,
• The overall survival after 10 years was 84%.
• Long bridges had lower survival than the shorter ones .
• Age of the patient did not influence the survival.
R. Napankangas , Longevity of fixed metal ceramic bridge prostheses: a clinical follow-up study,
journal of oral rehabilitation, 2002;Pages 140 - 145

• Failure rate and length of service of crowns and fixed partial dentures (FPDs) fabricated in a
Nigerian dental school. The reasons for failure of the initial restorations
• Poor esthetics ( 46%), Fracture (35.6%), Dental caries(15.4%).
• These outcomes were contrary to findings previously reported in studies from western countries
where dental caries was principally responsible for failures (22.0% to 38.0% of cases).
• The three-unit metal-ceramic FPDs had the greatest longevity at 8.6 years.
• The overall mean years of service for replaced restorations were 5.6 years.
• The study found a decrease in the mean years of service as the number of units in the fixed partial
dentures increased.
Oginni AO. Failures Related to Crowns and Fixed Partial Dentures Fabricated in a Nigerian
Dental School. J Contemp Dent Pract 2005 November;(6)4:136-143.

• 147 ZBR were evaluated after a mean observation period of 60 months.
• The technical and the biological outcomes of the ZBR were evaluated.
• Occlusal risk factors were examined: occlusal relationships, parafunctional habits and the presence of occlusal
nightguard.
• The results showed the survival rate of crowns and FPDs was 93.2%, the success rate was 81.63%.
• The chipping rate was 15%. Several parameters were shown to significantly influence veneer fracture: the absence of
occlusal nightguard, the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and
the presence of implants as support.
• The results of the study confirm that chipping is the first cause of ZBR failure.
Koenig V, Vanheusden A, LeGoff S and Mainjot A conducted a clinical risk factors related to
failures with zirconia-based restorations: an up to 9-year retrospective study.
Journal of Dentistry 41 (2018) 1164 – 1174

• This study was aimed to assess the periodontal status of Saudi adult females who had received regular oral
prophylaxis following the insertion of fixed partial dentures.
• The effects of sub- and supra-gingivally placed crown margins were also assessed.
• Sample size - 78 females who had fixed partial dentures.
• The plaque index, gingival index, probing pocket depth, tooth mobility and locations of the crown margins
were assessed and recorded by one calibrated examiner.
• The abutment teeth scored significantly higher plaque and gingival indices and greater probing pocket
depth than non-abutment teeth.
Al-Sinaidi A and Preethanath R (2018) conducted a study on the effect of fixed partial dentures on
periodontal status of abutment teeth.
The Saudi Journal for Dental Research 2018

• In addition, the abutment teeth scored greatest mean values of the clinical parameters in
subjects who were 46 year-old or older and those who had their functioning fixed partial
dentures for more than 5 years
• The teeth with supra-gingivally placed crown margins had significantly higher mean
values of plaque index, gingival index and probing pocket depth than teeth with sub-
gingival crown margins.
• The results of this study indicated that in subjects with fixed partial dentures, the
abutment teeth are more prone to periodontal inflammation than the non- abutment teeth.
• Additionally, the individual’s age, duration of insertion of fixed partial dentures and
location of the crown margins affect the periodontal health of the abutments.

• A total of 450 fixed partial denture failures in subjects were assessed.
• The FPDs was examined for the failure factors (biological, mechanical, and esthetic).
• Out of 450 FPDs failures, 33.3% of it showed the biological failure, 55.1% showed the mechanical failure
and 11.5% showed esthetic failure. The most frequent reason for failure was mechanical factors followed
by biological and esthetic failure factors.
• The caries was the most common biological failure factor, the loss of retention was the most common cause
of mechanical failure factor and the unacceptable color match was accounted more when compared to other
esthetic failure factors.
Chandranaik MB, Thippanna RK. Fixed Partial Denture Failures: A Clinical Survey for
Evaluation of the Factors Responsible. CODS J Dent 2017;9(2):41-45.
COD Journal of Dentistry, July-December 2017;9(2):41-45

• A total of 152 patients were recalled for clinical examination. Of these, 78 patients attended and were examined.
• The survival proportion of the examined 78 FDPs (all units of the original FPD) was 74.4%.
• The success proportion (FDPs without complications) was 52.6%.
• The most frequent complications were caries (14.1%), endodontic complications (11.5%), loose retainers (7.7%), root fractures
(5.1%), and framework fractures (3.8%). FDPs with post-and-cores (3.2%).
• This long-term retrospective study indicated that the prognosis for complicated and extensive FDPs in aging patients does not worsen
with increased clinical complexity. New materials, treatment complexity, and older patients did not seem to markedly influence
prognosis.
Helena Aenglund et. al A retrospective clinical evaluation of extensive tooth-supported fixed
dental prostheses after 10 years Volume 125, Issue 1, p65-72, January 2021
THE JOURNAL OF PROSTHETIC DENTISTRY

THE JOURNAL OF PROSTHETIC DENTISTRY

Objectives of Fixedprosthodontic Treatment
Chandrakala V, Deepmala S, Srivatsa G. Different classification system for failures in tooth supported fixed partial denture: a systematic
review. Int J Prev Clin Dent Res 2019;6:17-20
•Preservation and improvement of related hard- and soft-tissue structures
•Preservation or improvement of oral function
•Improvement or restoration of esthetics
•Ensuring restoration retention, resistance and stability
•Providing restoration with mechanical or structural integrity
•Preserving or improving patient comfort
•Designing restorations for maximum longevity.

Why do we need to know about complications?
Knowledge regarding the clinical complications that can occur in fixed
prosthodontics enhances
1. The clinician’s ability to complete a thorough diagnosis,
2 . Develop the most appropriate treatment plan,
3. Communicate realistic expectations to patients, and
4. Plan the time intervals needed for post-treatment care

Classification system for Failures in Tooth Supported
Fixed Partial Denture

• The causes of FPD failures were summarized as early as in 1920
when
Tinker wrote –
• “ Chief among the causes for such disappointing results have been:
• First : Faulty or no attempt at diagnosis and prognosis.
• Second: Failure to remove foci of infection
• Third: Disregard for tooth form
• Fourth: Absence of proper embrasures
• Fifth: Inter-proximal spaces
• Sixth: Faulty occlusion and articulation” Tinker ET. Fixed bridge-work. J Natl Dent Assoc 1920;7:579-95.

Thayer Classification – 1984
Thayer KE. Textbook of Fixed Prosthodontics. 2nd ed. Chicago, Year Book Medical Publishers, Inc. 1984.
•Caries
•Cement failures
•Preparation fractures
•Acrylic veneer wear/loss
•Porcelain fractures
•Solder joint or major connector failure
•Periodontal involvement.

Smith Classification – 1985
Smith B, Howe L. Planning and Making Crowns and Bridges. 4th ed.: CRC Press; 2013.
1.Loss of retention
1.Mechanical failures of crown and bridge components
1.Changes on abutment tooth
1.Design failures
1.Inadequate clinical or laboratory technique
1.Occlusal problems

1.Loss of retention
1.Mechanical failures of crown and
bridge components
• -Porcelain fracture
• -Failure of solder joints
• -Distortion
• -Occlusal wear and perforation
• -Lost facings

1.Changes on abutment
tooth
• -Periodontal disease
• -Problems with the pulp
• -Caries
• -Fracture of the prepared natural
crown or root
• -Movement of the tooth

1.Design failures
1.Inadequate clinical or laboratory
technique
• Marginal deficiencies
• Defects
• Poor shape and color
1.Occlusal problems

Wise Classification – 1999
Wise MD. Failure in the restored dentition; management and Treatment. Quintessence: London. 1995;397-412.
1.General pathosis
1.Periodontal problems
1.Caries
1.Pulpal changes
1.Erosion
1.Cracked teeth
1.Subpontic inflammation
1.Temporomandibular joint disorders
1.Occlusal problems.

John. F. Johnston Classification - 1986
Biological
Failures
Mechanical
Failures
Esthetics
Failures
Facing
Failures
Dykema RW, Goodacre CJ, Phillips RW. Johnston's Modern Practice in Fixed Prosthodontics. 4th ed. Philadelphia, London: W B Saunders Co.; 1986

1. Improper case selection
2. Improper treatment planning
3. Due to defects/deficiencies in different techniques
4. Due to occlusal discrepancies introduced with new restoration
5. Due to improper Maintenance

1. Improper case selection :
Lack of proper medical history to rule out general pathosis
Patients with High caries index & unrealistic demands
Periodontally compromised abutments & Long span FPD
Patients with large amount of bone loss
Patient with undiagnosed habit of bruxism

2. Improper Treatment Planning:
i) Improper selection of abutment & restorative material
ii) Inadequate Bridge Design
- Under-prescribed (cantilevered, intra-coronal retainers)
- Over-prescribed (long span bridges )
iii)Occlusal discrepancies (pathologic occlusion)
iv) Periodontal problems ( subgingival margins, inflamed gingiva, pockets, crown
lengthening)
v) Improper restoration of decayed tooth structure.

2. Improper treatment planning:
vii) Endodontic failure of abutment
viii) Post & core not considered
ix) Failures in post & core
a. Inadequate post length
b. Damaged apical seal
c. Lack of ferrule
d. Excessive post diameter
e. Lack of rotational resistances & stress distribution
f. Fracture of cast post & core
g. Distortion of wax pattern
h. Fracture of core due to inadequate strength of material for core build up

A) Clinical technique
i) Defects in tooth preparation
 Damage to adjacent tooth
 Soft tissue injury
 Pulpal injury
 Excessive tooth reduction
 Inadequate reduction
 Improper margin placement
 Improper margin geometry/ selection

Inlay placed in weaken tooth
Improper retention form due to increased taper, short axial walls/less
surface area & cement failure
Improper resistance form due to sharp angles, short tooth preparations
with large diameter
Improper aesthetics due to display of metal, minimum thickness of
porcelain
Supragingival margins at high esthetic zone

ii) Defects in impression making
a. Improper gingival retraction
 Adrenaline cords in cardiovascular disease patient
 Traumatization of gingiva
 Permanent loss of attachment (>5min)
 Pulpal inflammation due to acidic hemostatic agent

b) Improper handling & manipulation of impression material
Inadequate ratio of base & catalyst
Incomplete mixing
Hydrophobic nature of materials
Delayed insertion
Premature removal
Distortion during removal
Inadequate adhesion of material to tray

b. Improper handling & manipulation of impression material
Delayed pouring
Inadequate bulk of material
Incomplete polymerization
Bubbles due to air incorporation
Rough chalky surface due to inadequate cleaning
Improper pouring of dental stone

iii. Defects in cementation
Due to incorrect manipulation of cements
Due to poor cementation technique
Due to poor choice of luting agents

B) Laboratory techniques
i) Casting defects
 Complete misfit
 Partial castings
 Rolled margins
 Porosity
 Finning
 Nodules
 Pitting
 Contamination
 Over & under expansion
 Distortion

ii) Defects in Pontic
Larger pontic in inadequate space
Pontic given in severely resorbed ridges
Inadequate strength of material
Pontic in improper occlusion
Improper contours
Impingement of pontic on the tissues
Incompatible material in contact with tissues
Improper selection of pontic design

iii) Defects in connector
Casting defect
Failure of solder due to:
a. Contamination
b. Incomplete flow of solder
c. Oxidation
d. Improper distance (ideal 0.13mm)
e. Improper soldering technique
f. Insufficient bulk
g. Improper selection of joint

4. Due to occlusal discrepancies introduced with new restoration
5. Due to improper Maintenance

Failures in FPDs can be simply classified as:
Biologic
Aesthetics
Mechanical
Psychogenic
Donald W. Fisher/William W Morgan
MODIFICATION AND PRESERVATION OF EXISTING DENTAL RESTORATIONS

Biologic Mechanical Aesthetics Psychogenic
Caries Connector Failure Immediate Lack Of Counselling
Pulpal Degeneration Occlusal Wear Delayed
Endodontic Tooth Fracture
Periodontal Porcelain Fracture
Tooth Perforation Loss Of Retention
Subpontic Inflammation
Occlusal Problems
General Pathosis
Maintenance Failure
1.Dykema R.W., Goodacre C.J. and Phillips R.W. “Johnston’s Modern Practice in Fixed Prosthodontics”. Fourth Edn, W.B.
Saunders Co. Philadelphia, London.

Caries
One of the most common biologic failures
Causes
 Defective margin placement and adaptation
 Perforation
 Wearing a loose F.P.D. for a long time
 Poor oral hygiene
 Improper temporization
 Poor pontic form which fills the embrasures
 Surface roughness
 Dissolution of the luting cement

• Schwartz et al (1970) & Randow et al (1986) both reported caries to
be the most frequent cause of failure of existing restorations (36% &
18.3%).
• Glantz et al in 1993 reported that of 77 bridge reviewed at 15yrs ,
32.5% required removal. Further reported in 1993 that the incidence of
caries was not related to the age of the patient rather to the time that
the bridge had functioned .

Symptoms
• Perceived by the patient as pain or sensitivity to hot, cold and sweet
food/liquids
• Bad taste
• Bad breath
• Loose restorations
• Fractured teeth
• Discoloured teeth
Detection
• Visually (if present on labial surface)
• By probing (Tactile)
• Radiographs (if present interproximally)

Treatment
• If the caries is minor and restricted to the facial surface  restore without removing the
prosthesis
• Material used for such restoration in order of preference is silver amalgam, composite
resins and glass ionomers, depending on location on anterior or posterior teeth.
• Extensive lesions may require
-Removal of prosthesis and restoration
-Endodontic treatment
-Extraction followed by fabrication of a new prosthesis

Prevention
• Ensuring adequate marginal adaptation during try-in of restoration
• Educating the patient in maintaining oral hygiene
• Reviewing the same during recall appointments

Caries of tooth Adjacent to Retainer
• The main cause for this is lack of proximal contact at the time of
cementation.

PULP DEGENERATION
Manifestation
 Pain on percussion
 Sensitivity to hot and cold
 Tenderness
 Apical pathology on x-ray

PULP DEGENERATION
Causes
 Inefficient cooling and too rapid preparation of tooth.
 Lack of protection of prepared abutment during construction.
 Residual caries
 Occlusal trauma
 Defective margins

PULP DEGENERATION
Management
 Endodontic treatment followed by remaking of F.P.D
 Relieving of premature contacts
 Occlusal equilibration

PULP DEGENERATION
Prevention
 Proper diagnosis and restorative treatment should be done prior to prosthetic treatment.
 Use of high speed hand piece with feather light touch
 Use of water spray
 Temporary used should be well contoured, well extended with proper adaptation.
 Proper occlusal equilibration should be done prior to fabrication of F.P.D. and also at the time
of insertion.
 Proper designing of F.P.D. with well extended and adapted margins.

Endodontic Failure of Abutment
Causes:
• The endodontic treatment of the abutment was improper or inadequate.
• A root perforation or crack of the tooth during the old endodontic treatment may
manifest much later.
Symptoms:
• Perceived by patient as pain on biting or swelling.
Detection:
With the help of symptoms and radiographs.

Treatment:
• Extraction must be postponed if possible.
• Endodontic retreatment and apicoectomy may be attempted through the retainer or after
removing the prosthesis.
• Karlsson (1986) demonstrated that 10% of 641 bridge abutments exhibited periapical lesions
after 10 years, 19.8% of 303 root filled abutments exhibited non-healed periapical lesions.
• This conveys that just the presence of lesions on radiographs may not necessitate any treatment.
• Patient symptoms need to be assessed.

Prevention:
• Endodontically treated teeth must be used as abutments only after
thorough evaluation.
• If endodontic treatment is found inadequate, retreatment may be
performed.
• When in doubt, the design of the prosthesis should be altered to
exclude the tooth as abutment.

Periodontal Breakdown
Manifestations
 Gingival enlargement
 Mobility of abutment
 Deepening of pocket
 Loss of supporting structures
 Deposition of calculus

Failure to completely treat the
periodontal condition before
giving the prosthesis.
Poorly designed
prosthesis
Poor oral hygiene/
plaque control
Occlusal stress of
pathological nature
Systemic factors
leading to plaque
accumulation
CAUSES OF PERIODONTAL BREAKDOWN

MANAGEMENT
Plaque accumulation Prophylaxis, removal of local factor
Tissue hyperplasia Gingivoplasty
Devitalized & severe bone loss Endodontic procedure/hemi section
of teeth.
 Less severe breakdown can be treated without fear of loss of teeth,
with small surgery

PREVENTION
• Any existing periodontal disease must be eliminated and tissues should
return to optimal health before commencing fixed prosthodontics treatment.
• The prosthesis should be supported adequately by sufficient number of
abutments to function on a long term basis.
• Patient should be instructed on proper oral hygiene measures and
implementation must be verified through recall appointments.

Tooth Perforation
• Causes
• Tooth perforation can occur during:
• Placement of pinholes/pins
• Endodontic treatment
• Preparation for post and core

Treatment:
• Endodontic treatment is performed when pinholes or pins perforate into pulp chamber.
• If perforation is located occlusal to alveolar crest, preparation can be extended to cover defect.
• If located below crest and is accessible, perforation can be sealed through periodontal surgery.
• If perforation is inaccessible then the abutment requires extraction.
Furcation region:
• Surgically inaccessible
• Severe periodontal problems may ultimately lead to
extraction of the tooth.

Sub Pontic Inflammation
Causes:
• Excessive pressure by pontic due to improper pontic design and pontic
contacting too large an area
• Improper prosthesis design
• Poor maintenance of oral hygiene by the patient

Symptoms:
• Perceived by the patient as pain, swelling, bad breath, bad taste, bleeding
gums and poor aesthetics.
Treatment:
• If improper design is the problem, the prosthesis should be refabricated with
proper design after allowing the inflammation to subside.
• Patient should be educated to maintain the pontic space using aids like super
floss.

OCCLUSAL PROBLEMS
One of the objective……….
 Patients may be uncomfortable with their new occlusions.
 Some patients tolerate gross occlusal discrepancies without complaining , whereas others
are intolerant to discrepancies in the range of 10-15 microns.
 General discomfort with the “bite”
 Sore or Sensitive teeth
 Loose teeth or bridges
“Tired” or “sore” muscles

Occlusal interferences are undesirable occlusal contacts that may produce
mandibular deviations during closure to maximum intercuspation or
prevent smooth passage to or from maximum inter cuspal position .
There are four types of occlusal interference
Centric
Working
Non-working
Protrusive

• Interfering centric and eccentric occlusal contacts can cause:
Excessive tooth mobility
Irreversible pulpal damage
Neuromuscular discomfort
Bruxism
Trauma to soft tissues

Causes and Treatments
• Interfering centric or eccentric contacts  tooth mobility and irreversible
pulpal damage.
• Tooth mobility is reversible if problem is detected early and adjusted but
correction may cause prostheses failure due to perforation and loss of
aesthetics.
• Pulpal damage should receive endodontic treatment following occlusal
correction.

• Mobility due to long term occlusal interferences on normal teeth and due to
traumatic occlusion on teeth weakened by periodontal disease, are treated by
removing FPD and splinting teeth with removable prosthesis.
• If mobility is severe, extraction is necessary.
• An altered vertical dimension also leads to occlusal problems.
• This is the result of poor treatment planning and needs to be identified and
corrected.
• It may also lead to temporomandibular disorders.

General Pathosis
• Failure to diagnose a pathological change, having a vital bearing on the patient’s life
expectancy is a failure.
• For example a patient with a squamous cell carcinoma being treated for missing teeth
with a FPD instead of the more important condition is a failure.
• Many times patients come back to the dentist after many years for restorative
treatment. Patient’s current medical condition should be evaluated.
• A change in a patient’s medical condition like cerebral hemorrhage alters patient’s
motivation, physical ability to maintain teeth, diet and general resistance, leading to a
deterioration of restorations and abutments

Maintenance Failure
• Maintenance of the prosthesis is very important for the biologic
survival of the restoration.
• Failure may be due to:
Failure of the dentist to prescribe a maintenance program
Failure to implement or prescribe a recall system
Inadequate motivation of patient
Inadequate motivation by dentist

FAILURES IN FIXED PARTIAL DENTURES

FAILURES IN FIXED PARTIAL DENTURES (PART-II)
DEPARTMENT OF PROSTHODONTICS
3rd Year Resident

Failures in FPDs can be simply classified as:
Donald W. Fisher/William W Morgan
MODIFICATION AND PRESERVATION OF EXISTING DENTAL RESTORATIONS

Caries Connector Failure Immediate Lack Of Counselling
Pulpal Degeneration Occlusal Wear Delayed
Endodontic Tooth Fracture
Periodontal Porcelain Fracture
Tooth Perforation Loss Of Retention
Subpontic Inflammation Cementation Failure
Occlusal Problems
General Pathosis
Maintenance Failure
1.Dykema R.W., Goodacre C.J. and Phillips R.W. “Johnston’s Modern Practice in Fixed Prosthodontics”. Fourth Edn, W.B.
Saunders Co. Philadelphia, London.

LOSS OF RETENTION
Retention is the quality of preparation that prevents the restoration
from being dislodged by forces parallel to its path of withdrawal.
 Looseness or sensitivity to temperature or sweets.
 Bad taste or odour.

FREEDOM OF DISPLACEMENT
• Retention is improved by geometrically limiting the numbers of paths
along which a restoration can be removed from the tooth preparation.

Causes of Retention Failure
Excessive
Taper
Short
Clinical
Crowns
Misfit
Improper
Cementation
Procedure

MANAGEMENT
Clinical conditions with excessive taper and short clinical crowns should be treated with :-
• 1. In case of Excessive Taper:
 Incorporation of proximal grooves
 Additional retentive grooves (should be along with the path of insertion)
• 2. In case of Short Crowns:
 Crown lengthening procedure
 Modification of supra-gingival margin Sub-gingival margin
 Additional retentive grooves and proximal box
 Post & Core Procedure
 Addition of extra abutments

MISFIT
The misfit can occur at different locations :
1. Internal gap
2. Marginal gap
3. Vertical marginal discrepancy
4. Horizontal marginal discrepancy
5. Over-extended margin
6. Under-extended margin

CAUSES FOR MISFIT
• Distortion of the metal substructure
• Distortion of the margins (towards the tooth surface)
• Improper water/powder ratio
• Improper mixing time
• Improper burnout temperature
• Metal bubbles in occlusal or marginal regions
• Inadequate vacuum during investing

CAUSES FOR MISFIT
• No surfactant
• Porcelain flowed inside the retainer
• Excessive oxide layer formation in inner side of the retainer (due to
contaminated metal or repeated firing of porcelain)
• Tight contact points
• Thick cement space
• Insufficient pressure during cementation procedure

Connector Failure
Causes:
• Inadequate connector width.
• This is usually due to supra-eruption of opposing tooth
• Internal porosity
• Incomplete casting or soldering which has weakened
the metal can also cause connector failure

Treatment:
• If the cause is supra-eruption  offending tooth may be contoured to provide
adequate clearance.
• If casting defect was the problem  most often a new prosthesis is made.
• Pontic can be removed by cutting through the intact connectors and a temporary
removable partial denture can then be inserted to maintain the existing space and
satisfy esthetic requirements.

Dovetail preparation in each restoration
adjacent to the broken connection

OCCLUSAL WEAR
Clinical features
• Attrition of the opposing teeth,
• Polished facets on the Retainers/Pontics,
• Gingival Recession or Inflammation.

Causes:
• Insufficient thickness of restoration due to inadequate preparation of
occlusal surface or lack of functional cusp bevel.
• Heavy chewing Forces
• Para-functional Habits
• Rough porcelain occlusal surfaces cause
wear of opposing natural teeth

Treatment
 If wear is due to inadequate preparation  a new prosthesis is made
after providing adequate clearance
Any rough porcelain surface should be polished or glazed.
For Bruxers, a night guard may be a solution.
When occlusal wear is anticipated  it is better to plan metal occlusal
surfaces opposing natural teeth or metallic restorations.

Tooth Fracture
1. CROWN FRACTURE:
Causes:
• Excessive tooth preparation leaving insufficient tooth structure to resist occlusal
forces.
• Endodontically treated abutment with excessive tooth structure loss.
• Abutment with large restorations.
• Interfering centric/eccentric contacts.
• Attempting to forcibly seat an improperly fitting prosthesis.

Treatment
Small defect restored with Amalgam, Composite Resin
Large defect- a new prosthesis is fabricated to include the fracture area
Partial coverage – changed to full coverage
Post and core if needed
Pulp exposure – Endodontic treatment
Increase resistance form by placement of bevels

ROOT FRACTURES :
Causes
• Trauma
• Forceful seating of a post and core.
• Fractures occurring during endodontic treatment.
Treatment
• If located well below alveolar bone, tooth must be extracted followed by a new prosthesis

Porcelain Fracture
• Porcelain fractures occur with both Metal Ceramic and All Ceramic
crown restorations.

Metal – Ceramic Porcelain Failures
Metal
Framework
Design
Occlusion
Metal
Handling
Procedure
Preparation,
Impression &
Insertion
Metal
Porcelain
Incompatibility

Metal Framework Design
• Sharp angles or extremely rough and irregular areas over the veneering
area serve as points of stress concentration.

• Porcelain fracture can also occur as a result of underlying perforation
in the casting.
• An overly thin metal casting that does not adequately support
porcelain leads to flexure and porcelain fracture.

OCCLUSION
• The presence of heavy occlusal forces or habits such as clenching and
bruxism can cause failure.
• Centric or Eccentric occlusal interferences which create deflective
contact of the opposing teeth can cause fracture of porcelain.

METAL HANDLING PROCEDURE
• Improper handling of alloy during casting, finishing or porcelain
application can cause contamination which leads to ceramic fracture.
• Excessive oxide formation in metal can also cause porcelain fracture.

FAILURES DUE TO IMPROPER PREPARATION,
IMPRESSION & INSERTION
• Teeth prepared with slight undercut can cause bending of prostheses during
insertion, which initiates crack propagation.
• Distorted impressions can also cause prosthesis failure.

• When teeth are prepared with feather-edge finish lines or if finish lines
are not recorded properly in impression, the technician may extend the
metal beyond finish line as finish line is vague.
• The thin metal may bind against tooth and initiate crack of overlying
porcelain.

METAL PORCELAIN INCOMPATIBILITY
• This happens rarely. This can be easily prevented if manufacturer’s
instructions are followed when choosing the porcelains for a particular
metal.

PORCELAIN REPAIR
Composite Repair Method :
a) - Mechanical roughening of fractured site Hydrofluoric acid
b) - Application of Silane coupling agent
c) - Application of Direct Opaque & Curing.
d) - Ceramic repair material added to site, cured and finished

ADVANTAGES:
• Less chairside time
• Lower cost
• Ease of application
DISADVANTAGES:
• Low strength
• Poor wear resistance
• Esthetics may compromise
• Long term success in load bearing areas is unpredictable.

• A more permanent repair is possible when adequate metal
framework thickness is available:
• This technique works best with facially veneered restorations and
involves the following steps.

Procedure :
1) Removal of the remaining porcelain on the fractured unit to expose the underlying metal.
2) Drilling of several pinholes (4 or 5) into the framework to a depth of at least 2 mm.
3) Making of an impression.
4) Creation of a pin – retained metal casting 0.2 to 0.3 mm thick out of a metal – ceramic alloy to fit over the
exposed metal framework.
5) Fusion of porcelain to the pin – retained.
6) Cementation of the casting in position.

PORCELAIN JACKET CROWN FAILURES
• The quality of the tooth preparation & the magnitude of the occlusal forces
present are the predominant factors that determine clinical success or failure.
• The tooth preparation must provide adequate ,but not excessive tooth
reduction & must be designed to support the restoration since no metal is
present to provide support.

• Three main types of Failures are as follow..
VERTICAL
FACIAL
CERVICAL
LINGUAL

VERTICAL FRACTURE
• The marginal area of jacket crowns is often more closely
adapted to the prepared tooth than are other areas of restoration.
• If a tapered finish line is used, the restoration may contact the tooth on a sloping surface,
so that forces are produced that attempt to expand the restoration and that are not well
resisted by porcelain.
Sharp areas on
the prepared tooth
High stress concentration
Within the restoration
VERTICAL
FRACTURE

FACIAL CERVICAL FRACTURE:
It occurs in a semi lunar form mainly due to short tooth preparation.
Ideally the inciso-cervical length  Two third or three quarter of final restoration.
When opposing tooth contact is located incisal to the prepared tooth tipping forces
are more frequently developed.

LINGUAL FRACTURE
Semi-lunar lingual fracture is seen when occlusion is located cervical
to the cingulum of the preparation, where forces on the porcelain are
more shear in nature & not as well resisted.
Inadequate lingual tooth reduction.
Heavy occlusal forces

ESTHETICS FAILURE
Ceramic restorations more often fail esthetically than mechanically or
biologically.
Poor color match is the frequent reason for most of the remakes of the
restorations.
(J Int Dent Med Res 2010; 3: (3), pp. 146-153 )

Causes –
Failure to identify patient expectations regarding esthetics
Improper shade selection
Failure to transfer the shade to dental laboratory.
Excessive metal thickness at incisal and cervical region
Thick opaque layer application
Over glazing or too much smooth surface

Metal exposure in connector, cervical or incisal regions
Failure to produce incisal and proximal translucency
Improper contouring
Failure to harmonize contra lateral tooth morphology
• Color
• Contour
• Position
• Angulation

Recession leading to Esthetic Failure
• The marginal fit or cervical form of a prosthesis can promote plaque accumulation,
causing gingival inflammation, which produces an unnatural soft tissue color or form
that is esthetically unacceptable.

CEMENTATION FAILURE
It includes
Cement Failure
1. Cement selection
2. Old cement
3. Prolonged mixing time
4. Thin mix
5. Thick mix
6. Cement setting prior to seating

7. Inadequate isolation
8. Incomplete removal of temporary cement
9. Thick cement space
10. Inclusion of cotton fibers
11. Insufficient pressure while cementation

PSYCHOGENIC FAILURE
When all the parameters for a successful FPD have been met with, rarely a patient
may still feel uncomfortable with the restoration.
This has been attributed to the stress and behavioral changes in the individual.
The patient may require counselling to get over this problem.
A failure to recognize this problem during the diagnostic phase itself, can lead to a
failure of the prosthesis.

Fixed prosthodontic treatment does not end with the fitting of
restorations.
Subsequent maintenance is an integral part of treatment. If this is not
adequately prescribed, failure can occur.
The first consideration when confronted with any failure is to ascertain
the cause.
If there is a cause that is correctable, it should be taken care of first.
Failures most often occur because of violation of principles either
collectively or individually.

Care should be taken not to become involved in repairs that should
have been remakes.
Repairs are usually the second best to the original in one or more
ways.
Most failures are unique and present varying challenges to the dentist.
Therefore treatment plan for each situation must be individualized.

Planning and making crowns and bridges. Smith B, Howe L. 4th edition. Abingdon, Informa
healthcare.
Contemporary fixed prosthodontics. Rosenstiel S, Land M, Fujimoto J. 4th edition. St Louis,
Mosby Elsevier.
Shillingburg HT, Hobo S, Whitsett LD, Jacobi R, Brackett SE. Fundamentals of fixed
prosthodontics. Quintessence Publishing Company.
Koenig V, Vanheusden A, LeGoff S and Mainjot A. A clinical risk factors related to failures with
zirconia-based restorations: an up to 9-year retrospective study. Journal of Dentistry 2018;41:1164
– 1174.
E. G. Kontakiotis, C. G. Filippatos, S. Stefopoulos & G. N. Tzanetakis. A prospective study of the
incidence of asymptomatic pulp necrosis following crown preparation. International Endodontic
Journal 2017.

Seong LG, May LW. Key Indicators of success or survival for clinical performance of fixed partial
denture. Annals of Dentistry University of Malaya. 2019 Dec 3;26:53-8.
Kapoor C, Vaidya S. Evaluation of Complications Associated with Fixed Partial Denture-An
observational study. Journal of Advanced Medical and Dental Sciences Research. 2019 Aug
1;7(8):149-52.
Al-Sinaidi A and Preethanath R. A study on the eﬀect of ﬁxed partial dentures on periodontal status
of abutment teeth. The Saudi Journal for Dental Research 2018.
Triwatana P, Nagaviroj N, Tulapornchai C. Clinical performance and failures of zirconia- based fixed
partial dentures: a review literature. The journal of advanced prosthodontics. 2012 May 1;4(2):76-83.
Muddugangadhar BC, Amarnath GS, Sonika R, Chheda PS, Garg A. Meta-analysis of failure and
survival rate of implant-supported single crowns, fixed partial denture, and implant tooth-supported
prostheses. Journal of international oral health: JIOH. 2015 Sep;7(9):11.

Swain PK. Failure Rate in Fixed Partial Denture Patients-A Clinical Study. Journal of
Advanced Medical and Dental Sciences Research. 2018 Oct;6(10).
Jain JK, Sethuraman R, Chauhan S, Javiya P, Srivastava S, Patel R, Bhalani B. Retention
failures in cement-and screw-retained fixed restorations on dental implants in partially
edentulous arches: A systematic review with meta-analysis. The Journal of the Indian
Prosthodontic Society. 2018 Jul;18(3):201.
Alraheam IA, Ngoc CN, Wiesen CA, Donovan TE. Five‐year success rate of resin‐bonded
fixed partial dentures: A systematic review. Journal of Esthetic and Restorative Dentistry.
2019 Jan;31(1):40-50.
Walton J N, Gardner F M, Agar J R : A survey of crown and fixed partial denture failures
: length of service and reasons for replacement. JPD 1986:56; 416-21

• Libby BSG, Arcuri MR, LaVelle WE, Lisa Hebl Longevity of fixed partial
dentures JPD 1997; 78 : 127- 31.
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treatments and agents for composite-to-porcelain repair. JPD 1996;76:119-
24.
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resistance form of dislodged crowns and retainers JPD 1998;80:405- 9.
• James S. Marcum - The effect of crown marginal depth upon gingival tissue
JPD 1967;17: 479-88.

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