Malabar Dental College

2.  Introduction
 Classification of Failures
 Biological Failures
◦ Diagnosis and treatment planning.
◦ Abutment selection.
◦ Caries.
◦ Pulpal degeneration.
◦ Periodontal breakdown.
◦ Occlusal problems.
◦ Changes in vertical dimension.
◦ Tooth perforation.
◦ Subpontic inflammation.
◦ Temporomandibular disorders.

3.  Mechanical Failures
◦ Loss of retention
◦ Connector failure
◦ Occlusal failure
◦ Tooth fracture
◦ Root fracture
 Porcelain Fractures
◦ Metal ceramic porcelain failures
◦ Occlusion
◦ Metal handling procedures
◦ Metal with porcelain incompatibility.
◦ Preparation, impression and insertion.
◦ Porcelain jacket crown failures
◦ Vertical fracture.
◦ Facial cervical fracture.
◦ Lingual fracture.

4.  Esthetic failures
 Maintenance failures
 Repair of fracture porcelain units
 Summary & Conclusion
 References

6.  Biologic failures
 Mechanical failures
 Esthetic failures
 Maintenance failures

7.  Many failures occur because the dentist does
not take time to do a thorough diagnosis and
plan for success.
 The four major diagnostic aids to making a
dental diagnosis are :
 Taking a history
 Doing a careful clinical examination
 Having a complete set of radiographs
 Having a good set of diagnostic casts correctly
mounted.

8.  The selection of an abutment tooth depends on
the length of span of the restoration and the
amount of stress that will be applied to the
abutment .
 The strength of a tooth is directly proportional
to the amount of periodontal ligament that
attaches the tooth to bone.
 Minimal requirement for an abutment tooth is a
1:1crown :root ratio,and the root should not be
mobile or conical shape.

9.  A simple guide in deciding whether to make a
fixed or a removable partial denture is ante’s
rule comes in to play.
 “In fixed bridges the combined pericemental
area of the abutment teeth should be equal to
or greater in pericemental area than the teeth
to be replaced.”

10.  Caries :
 This is usually perceived by the patient as
 Pain or sensitivity due to hot, cold or sweet
foods and liquids
 Bad taste
 Bad breath
 Loose restoration
 Fractured teeth
 Discolored teeth

11.  Early detection is possible through
comprehensive probing of the margins of
the prosthesis and tooth surfaces with sharp
explorer.
 Radiographs are helpful in detection of
caries inter proximally.
 Conventional operative procedures can be
used to restore small carious lesions with
out need to fabricate new prosthesis.
 Gold foil is the material of choice for
restoring marginal caries.

12.  Amalgam is the alternative material because it
produces long term marginal seal.
 Caries in the proximal surfaces my require
removal of the prosthesis to obtain access to
caries.
 If the leasion is small the tooth preparation
can be extended to eliminate the caries and
new prosthesis fabricated .
 When larger lesion is present an amalgam
restoration is often required after removel of
restoration and excavation of caries. The
aburtment preparation is extended to cover
the filling and a new restoration is fabricated.

15.  Extensive lesions my encroach the pulp
making endodontic treatment necessary or
if it is not possible then the tooth has to be
extracted.
 Marginal caries lesions generally begin at
surface which progress inward .
 They occur internally which are lost
discrenabele externally until extensive
distruction . This problem can be the result
of incomplete removal of caries during a
previous treatment or of aloose retainer
casting that allows gross leakage to occur.

16.  This is usually perceived by patient as :
 Pain either spotaneous or related to hot , cold
or sweet stimuli.
 Pain which is accentuated by lying down or
exercise.
 Post insertion pulpal sensitivity on abutment
teeth that does not subside with time intense
pain or per apical abnormalities that are
detected radiografically often indicate need

17.  Access to the pulp requires preparation of a
hole the prosthesis through which necessary
treatment is completed.
 The perforation can be restored with gold foil ,
amalgam or a cast metal inlay with out
compromising the prosthesis.
 During endodontic treatment an assessment
should be made of quantity and quality of the
tooth structure remaining for support and
retention of restoration.

19.  This is perceived by the patient as :
 Loose ness of teeth or bridge work
 Drifting of teeth
 Bleeding tissues
 Changes in color of gums
 Bad taste
 Bad breath
 Pain which is some times received by
applying side ways pressure from opposing
tooth .
 Abscess formation
 Poor esthetics

20.  Periodontal disease can produce extensive
bone loss results in the loss of abutment
teeth and attached prosthesis.
 Less severe breakdown can be treated with
out fear of loss of teeth but treatment
involves surgery. Which my produce an
unacceptable relationship between prosthesis
and the soft tissue.
 The disease process may be present in both
restored and un restored areas of mouth in
same situations with no relationship to

22.  Poor marginal adaption
 Over contouring of the axial surfaces of
the retainer.
 Excessively large connectors that restrict
cervical embrasure space.
 Pontic that connects too large an area on
the edentulous ridge.
 Prosthesis with rough surfaces that
promotes plaque accumulation.

23.  The patient may be uncomfortable with their
new occlusions
 Some patients tolerate gross occlusal
discrepancies without complaining whereas
others are intolerant with discrepancies in the
range of 10-15 micro meters.

24.  Occlusal discrepancies can be perceived by
the patient as :
 General discomfort with the bite.
 Soar teeth
 Loose teeth or bridges.
 Sensitive teeth.
 Tired or soar muscles.

25.  The vertical dimension may be decreased as a
result of severe attrition or increase as a
result of poor restorative planning
 Often the increase occurs from the use of
porcelain on occlusal surfaces in short clinical
crowns

26.  The following symptons may be
perceived by the patient :
 Altered facial appearance
 Drooling of saliva
 Loss of vertical dimension which can
precipitate angular chelitis.
 Alteration in muscle activity can cause
myalgia

27.  Extreme increase in the vertical dimension
can reduce ability of the tongue to create a
seal during swallowing
 Teeth can become sensitive either due to
wear or trauma to the teeth from increased
vertical dimension.
 They complain of clashing of teeth because
of premature contacts

28.  Loss of posterior dimension can result in
the lower anterior teeth occluding more
heavily with the palatal surface of the
anterior teeth causing drifting or failure of
anterior restoration
 A decrease in vertical dimension can result
in lower incisors occluding with the palatal
soft tissue giving rise to soreness and
possible periodontal complications.
 Alteration in vertical dimension can cause
difficulty in mastication
 Gross increase in vertical dimension can
cause speech problems particularly with

29.  Interfering centric or eccentric occlusion
contacts can cause excessive tooth mobility.
 If it is detected early the interferences can be
eliminated by occlusal adjustment with out
permanent damage .
 Occasionally the combination of excessive
mobility with reduced bone support require
extraction of abutment teeth.
 The presence of interfering occlusal contacts
can also cause irreversible pulp damage
requiring endodontic treatment.

30.  Pin holes or pins used with retained
restorations can be improperly located and
may perforate the tooth laterally.
 If perforation is located occlusal and the
periodontal ligament.it is often possible to
extend the tooth preparation and cover the
defect.

31.  When the perforation extends in to the
periodontal ligament . It my be possible to
perform periodontal ligament surgery and
smooth off projecting pin or place a
restoration in to an perforated area.
 Lateral perforations become apparent only
after insertion of prosthesis.
 Endodontic treatment is required when
pinholes or pins may perforate in to the pulp
chamber.

32.  It is perceived by the patient as :
 Pain swelling
 Bad breath
 Bad taste
 Bleeding gums
 Poor esthetics

34.  Restoration which precipitate such
disorders could lead to patient
dissatisfaction.
 The useful classification of T.M.J DISODERS
IS:
 FACIAL ARTHROMYALGIA : also termed as
myofacial pain dysfunction syndrome.
 It involves pain in or around muscles of
mastication (myalgia) and T.M.J (arthralgia)
 The pain is usully long standing deep

35.  This implies disturbance in meniscus.
 It may be displaced interiorly and medially
with or with out reduction and is associated
with adhesion formation.
 Patient my complain of clicking, irregular
movement, locking or grating sounds which
can occur with or with out joint pain.
 ARTHROSIS AND ARTHRITIS:It is degenerative
disorder of the joint in which the joint form
and structure are abnormal.

36. Loss of retention :
 A prosthesis can come loose from an
abutment tooth and if this occurrence is not
detected early extensive caries often develops.
 The patient may be aware of looseness or
sensitivity to temperature or sweets .
 There my be recurring bad taste or odour
which must be differentiated from similar
symptoms caused by poor oral hygiene or
periodontal problems.

37.  Periodic clinical examination should include
attempts to un seat existing prosthesis by
lifting the retainers up and down (
occlusocervically ) while they are held
between fingers and curved explorer placed
under the connector.
 If casting is loose the occlusal motion causes
fluids to be drawn under the casting and
when casting is reseated with cervical force
the fluid is expressed generally producing
bubbles as the air and liquid are

38.  When retainer comes loose the prosthesis
must be removed so that the abutment teeth
can be evaluated.
 If the restoration can be dislodged from other
prepared teeth with out damage and if no
caries is present it is possible to re cement
the restoration .
 Improper cementation procedure may have
caused the problem.

40.  Inadequate tooth preparation
 Poor fit of casting
 In correct manipulation of cement
 Poor cementation technique
 Occlusal mismanagement

41.  Different mobility's between abutment so
that the most mobile abutment is
hydraulically displaced during
cementation.
 Poor mechanical design of restoration
 Poor choice of materials
 Excessive forces as in cantilever bridge
work.

42.  A connector between an abutment and a
pontic or between two pontics can fracture
under occlusal forces.
 Failures of both cast and soldered connectors
have been observed and are generally caused
by internal porosity that weakens the metal.
 When fracture occurs pontics are placed in a
cantilevered relationship with the retainer
casting and this can allow excessive forces to
be developed on the abutment tooth.

43.  For this reason the prosthesis should be
removed and remade as soon as possible .
 Occasionally an inlay like dove tailed
preparation can be developed in the metal to
span the fracture site and casting can be
cemented to stabilize the prosthesis
 If this is not possible the the pontic should be
removed by cutting through intact connectors
 A temporary removable partial denture can be
placed to maintain the space between teeth.

45.  Restoration can wear ultimately through to
the underlying tooth leading to cement wash
out and subsequent failure or over eruption
of the opposing tooth.
 It is caused due to :
 Insufficient thickness of restorative material
 Inadequate control of occlusion
 Highly abrasive diet
 Poor abrasion resistanceof the restorative
materials.

46.  When occluding surfaces are restored with
metal casting perforation may develop after
several years since occlusal metal thickness is
limited by the allowable amount of tooth
reduction.
 Perforation allows leakage and caries to occur
which ultimately leads to prosthesis failure.
 If perforation is detected early a gold or
amalgam restoration can be placed that seals
the area additional yrs of service.

47.  If metal is extremely thin a new prosthesis
should be fabricated.
 When occlusal surfaces are covered with
procelain wear of ceramic material is not a
problem even in presence of heavy occlusal
forces.
 But if porcelain opposes natural teeth
dramatic wear of enamel my occur with
eventual penetration in to dentin.

49.  Coronal tooth fracture can be dramatic
resulting in considerable loss of tooth
structure or it can be minor with little
significant damage .
 Small coronal tooth fracture often leaves the
restoration adequately retained with only
formation of a small marginal defect.
 This type of problem occurs primarily around
inlays partial coverage crowns as the result of
wear with apparent brittleness of tooth

50.  If the restoration and tooth structure
surrounding the defect can be adequately
prepared and still possess sufficient
strength , gold foil, amalgam or resin can
be used to restore the area.
 If there is a question regarding integrity of
the remaining tooth structure or
restoration a new prosthesis should be
fabricated so that it encompasses fracture
area .

51.  Large coronal fracture around partial coverage
crowns it is impossible to restorethe teeth but
generally a full coverage restoration can be
made however the tooth my be require a
separate pin retained restoration to serve as a
core and provide support and retention for a
new prosthesis.

52.  Abutment tooth fractures under full coverage
retainers usually occur horizotally at the level
of the finish line so that little or no coronal
tooth structure is left.
 This requires removal of prosthesis
endodontic treatment a post and core with a
new prosthesis .
 Single restoration can be salvaged if finish
line with a little coronal tooth structure
remaine intact after fracture.
 A post and core can be fabricated to fit both

54.  They are often located well below the alveolar
bone crest so that the teeth so that the teeth
must be extracted and a new prosthesis be
fabricated.
 In some cases it terminates at or just below
the alveolar bone.
 In such cases it may be possible to perform
periodontal surgery remove the bone and
expose the fracture site so it can be
encompassed by a new prosthesis.

55.  These fractures are mainly caused due to:
 Trauma
 During endodontic treatment
 Forceful seawing of post and core
 Attempt to fully seat a improperly fitting post
and core.
 Short screw tapered with poorly fitting posts
are conducive to root fracture as is excessive
thinning of the root epically or gingivally.

57.  Porcelain fracture’s occur with both metal
ceramic and all ceramic restoration .
 Majority of metal ceramic fracture’s can be
attributed to improve design characteristics of
the metal frame work or due to problems
related to occlusion.
 All ceramic restorations most commonly fail
because of deficiencies in the tooth
preparation or presence of heavy occlusal
forces.

58. Frame work design :
 Sharp angles or extremely rough with
irregular area over the veneering area serves
as points of stress concentration that can
cause crack propagation with ceramic fracture
.
 Perforation in metal can also cause failure.
 An overly thin metal casting does not
adequately support porcelain so that flexure
porcelain fracture are allowed.

59.  Trial insertion of prosthesis , final
cementation forces or post insertion occlusal
forces could produce the failure.
 When the frame work thickness is less than
0.2mm over large area of veneering surface
the potential for failure is much greater
regardless of type of casting alloy.
 With facially veneered restoration porcelain
fracture result from a frame work design that
allows centric occlusal contact and or

60.  Also failure occur when angle between
veneering surface with on veneered surface
and the non veneered surface aspect of the
casting is less than 90 degrees.
 These designs allow occlusal forces to cause
localized burnishing of metal and distortion
which leads to premature porcelain fracture.

62.  The presence of heavy occlusal forces or habits
such as clenching or bruxism can cause failure.
 Centric or eccentric occlusal interferences can
also place forces on porcelain that one capable
of causing fracture as do uncorrected occlusal
slides which are deflective contact of the
opposing tooth with the prosthesis.

63.  Improper handling of the alloy during
casting,finishing or application of the porcelain
can lead to metal contamination.
 Bubbles may form at metal ceramic junction
when porcelain is applied creating stress and
possibly cracks.
 Separation of the porcelain from the metal has
been observed in cases of sever contamination.

64.  Excessive oxide formation on the alloy surface
can also cause separation of the porcelain from
the metal
 This problem is frequently caused by improper
conditioning of base metal alloys with certain
gold palladium or high palladium content.

65.  A tooth preparation with slight undercut can
cause binding of the prosthesis as it is seated
which initiated a crack in the porcelain.
 The fracture my be apparent during try in that
could go unnoticed un till premature post
insertion failure occurs.
 An impression that is slightly distorted can
cause same problem.

66.  Teeth prepared with feather edge finish lines
or impression that do not record all the finish
lines can lead to extension of metal beyond
the actual termination of tooth reduction
because it is difficult to determine from the
die or impression where to terminate the wax
pattern.
 The thin metal may bind against the tooth
which initiate a crack in the overlying
porcelain
 Definite finish lines with impressions are
important in this regard.

67.  In rare instances an alloy with porcelain are
found to be truly incompatible with
successful bonding with out loss of veneer or
cracking is impossible.
 How ever failure resulting from improper
handling of the material is often mistakingly
attributed to metal porcelain incompatibility.

68.  Since these crowns have been in use for nearly
a century considerable clinical experience
relating to their failure is available.
 With good tooth preparation long term
success has been achieved on incisors where
as fractures are more frequently observed
when these restorations are placed on
posterior teeth and on canines because of
occlusal force on these teeth.

69.  The quality of tooth preparation with the
magnitude of the occlusal forces present are
the predominant factors that determine clinical
success or failure.
 They are more likely to fail in the presence of
heavy occlusal forces clenching or bruxism .the
tooth preparation must be designed to support
the restoration since no metal is present to
provide support.

70.  The marginal area of jacket crowns is often
more closely adapted to the prepared tooth
than other areas of the restoration.
 If a chamfer 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.

71.  Sharp areas of the prepared tooth such as line
angles or incisal edge produce high stress in
the restoration that can cause these fractures.
 Vertical fractures have also been observed
when a large portion of the proximal
preparation form is missing and is not
restored prior to impression procedure .
 When occlusal forces are applied to the
marginal ridge in which the missing tooth
form is located greater leverage is developed.

72.  Because of the distance from point of force
application to the underlying prepared tooth.
 The occlusal forces attempt to rotate the
restoration causing expansive forces.
 A round preparation from that does not provide
adequate resistance to rotational forces can
also cause the same type of failure.

74.  It occurs in a semi lunar form mainly due to
short tooth preparation.
 The incisocervical length of the preparation
should be 2/3 to 3/4th that of final
restoration.
 When preparation is short forces applied at
incisal edge.attempt to tip the restoration
facially and cause cervical porcelain fracture.
 When opposing tooth contact is located
incisally to the prepared tooth tipping forces
are more frequently developed with
restoration having a fulcrum on the cervically

76.  Semi lunar lingual fracture is seen when
occlusion is located cervically to the cingulum
of the preparation where forces on the
porcelain are more shear in nature and not as
well resisted.
 Other lingual fractures are not semi lunar in
form are the result of inadequate lingual tooth
reduction in which less than 1mm of porcelain
is present.
 Exceptionally heavy occlusal forces also can
cause lingual fracture even when adequate

78.  Ceramic restoration often fail esthetically than
biologically or mechanically.
 One of the main reason is unacceptable color
match.
 This could be the result of the inability to
match patients natural teeth with porcelain
color.
 “metamerism” is an ever present problem that
contributes to poor color matching.

79.  Insufficient tooth reduction or failure to properly
apply and fire the porcelain may have created a
restoration that does not match the shade guide
or the surrounding teeth.
 Esthetic failures can also occur because of
incorrect form or a frame work design that
display metal. In addition natural teeth under go
color changes that do not occur in porcelain.

80.  Partial veneer crowns are esthetically
unacceptable because of over extension of
the finish line facially.
 This displays excessive amount of metal
even with proper facial extension and
artificial appearance can be created if the
facial out line form of the prepared teeth
does not resemble an unprepared tooth.
 The marginal fit or cervical form of a
prosthesis can promote plaque
accumulation causing gingivitis.

82.  Maybe due to following reasons :
 Failure to prescribe both the nature and the
frequency of specific recall appointment to
individual patient.
 Failure to implement a recall system.
 Inadequate motivation of the patient to
maintain the dentition and recall
appointment.

83.  Inadequate motivation of the dentist to
maintain an adequate recall system.
 Motivation of the the dental team. Motivation to
maintain ,monitor and motivate existing
patients.

84.  Two approaches to porcelain repair are
possible .
 If a larger area of porcelain has been lost,a
porcelain facing may be constructed,and
placed using a resin based luting
material,after first etching the porcelain
surface with hydrofluoric acid in a manner
similar to that employed in porcelain veneers.
 Alternatively if a lesser amount of porcelain is
lost , repair may be achieved by the

85.  The patient presented with the porcelain having
sheared off the metal substructure of the upper
right lateral retainer of a 9-unit metal /
porcelain bridge which had been constructed 11
yrs previously.
 Repair should be attempted by construction of a
new porcelain facing , to be placed using
superbond as metal/ porcelain luting material

86.  Minimal re-preparation of the metal
substructure of the retainer was carried out, an
elastomeric impression was taken , and an
occlusal record made.
 Inorder to provide protection of the airway from
aluminum oxide dust used in the procedure, and
the same time to provide isolation from
moisture , rubber dam was adapted over the
bridge as closely as possible.

89.  The patient was given protective eyewear and
nose piece for air way protection.
 The metal surface was sandblasted using an
an intraoral sandblaster for 10 seconds,
during which the surface become matt.
 A high volume aspirator was held close to the
site to remove the considerable amount of
dust which accumulated.
 Etch –free metal / porcelain was applied to the
exposed metal and porcelain surface s and
allowed to evaporate.

90.  Silane primer was applied to the fitting surface
of the porcelain facing.
 Super bond was mixed ,and applied to the
porcelain facing which was then placed on the
pontic.
 Excess resin was removed using a probe and
the facing was held in position for
approximately 10 minutes until a hard set of
the luting material had been achieved.

91.  The occlusion was checked in all in all
mandibular movements and the facing adjusted
as necessary.
 The patient was recalled after one week for final
finishing of the porcelain /pontic margins.

92.  The patient presented with a porcelain
fracture of the buccal aspect of the upper left
canine retainer of a three- unit bridge.
 Following isolation of the fractured retainer
by placement of rubber dam, the area of
porcelain fracture was sand blasted using the
microercher for 10 seconds.
 Apf porcelain etching gel was applied to the
fractured porcelain surface for2 minutes.

93.  After washing and drying the surface, the metal
priming solution was applied to the exposed
metal and allowed to evaporate off.
 A dual-cure un-filled resin was then applied to
the area of the fracture,and after curing, z100
composite was applied ,using first a dentine
shade of 1.5mm depth followed by a more
translucent shade to complete the repair
contour.

96.  The composite was finished using conventional
composite finishing / polishing techniques, and the
occlusion checked in centric relation and in
protrusive and lateral mandibular movements.

98.  Wise Michael D. “Failures in restored dentition:
Management and treatment”. 1st edn, Quintessence
publishing Co. Ltd., London, Berlin, Chicago and
Tokyo.
 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.
 Brown M.H. “Causes and prevention of fixed
prosthodontic failures”. J. Prosthet. Dent. 1973; 30:
617-622.
 Barreto M.T. “Failures in ceramometal fixed
restoration”. J. Prosthet. Dent. 1984; 51: 186-189.
 Mutlu Ozcan, Wilhelm Niedermeier “Clinical study on
the reasons for and location of failures of metal-

99.  Pruden K.C. “Abutments and attachments in fixed
partial dentures”. J. Prosthet Dent. 1957; 7: 502-
510.
 Burke E.J.T. and Grey N.J.A. “Repair of fractured
porcelain units: alternative approaches”. Br. Dent. J.
1994; 176: 251-256.
 Chung K.H. and Hwang Y.C. “Bonding strengths of
porcelain repair systems with various surface
treatments”. J. Prosthet. Dent. 1997; 78: 267-273.
 Walten J.N., Gardner F.M. and Agar J.R. “A survey of
crown and fixed partial denture failures: Length of
service and reasons for replacement”. J. Prosthet.