5. BENNARD G. N. SMITH
o Loss of retention
o Changes in the abutment tooth
o Periodontal disease
o Problems with the pulp
o Fracture of the prepared natural crown or root
o Movement of the tooth
o Mechanical failure of crowns or bridge components
o Porcelain fracture
o Failure of solder joints
o Occlusal wear and perforation
6. o Design failures
o Under-prescribed FPDs
o Over-prescribed FPDs
o Inadequate clinical or laboratory technique
o Positive ledge
o Negative ledge
o Poor shape and color
o Occlusal problems
7. JOHN F. JOHNSTON
o Looseness of FPD
o Recurrence of caries
o Recession of supporting structure
o Degeneration of Pulp
o Fractures of bridge components
o Loss of veneers
o Loss of function
o Loss of tissue tone or form
o Failure to seat
12. CLASS V
Severe failure with loss of supporting tooth or inability to reconstruct using
original tooth support. Fixed prosthodontic replacement remains possible
through use of other or additional support for redesigned restoration.
13. CLASS VI
Severe failure with loss of supporting tooth or inability to reconstruct
using original tooth support. Conventional fixed prosthodontic
replacement is not possible
14. Classification of chipping fracture treatments for
o Grade 1: Fracture surfaces were polished.
o Grade 2: Fracture surfaces were
repaired with resin-based composite.
o Grade 3: Severe chipping fractures required
replacement of affected prostheses.
Int J Prosthodont 2010;23:493–502.
Dental materials 2012 :28: 102–111
o Fluoride mouth washes
o Dental floss
o Diet counseling
o Professionally applied topical fluoride
o Antibacterial cements and anti-
microbial agents should be used to
decrease the caries incidence.
o Conventional operative dentistry procedures to
restore small lesions
o Endodontic treatment in case pulp is involved
19. Pulp degeneration
o Excess heat generated during preparation
o Excess tooth reduction
o Pin point exposure which may go unnoticed.
o Occlusal trauma
o Poor design
o Secondary caries
o Pulpal sensitivity
o Intense pain
o Radiolucencies in the periapical region
o Use of varnishes and dentin bonding
agents which forms an effective barrier
and prevents underlying pulp from toxic
effects of cement and core materials.
o Endodontic treatment of the involved
tooth by making an access opening
through the crown, once obturated the
perforation can be restored.
21. Periodontal breakdown
o Poor marginal adaptation and proximal contact
o Over contoured axial surfaces
o Excessively large connectors
o Large Pontic contacts on edentulous ridge.
o Prosthesis with rough surfaces
o Heavy occlusal forces
o Few abutment teeth
o Oversized food table
o Proper oral hygiene
o Scaling and proper plaque control.
o Flap surgery, bone grafts etc.
o In case of long span F.P.D., the F.P.D. must be removed and remade
with multiple terminal abutments.
o Narrowing occlusal table
24. Occlusal problems
o Centric and eccentric interferences
o Heavy occlusal forces
o Habits like bruxism, clenching
o Large wear facets
o Tenderness on percussion
o Open contacts
o Perforation and cusp fracture
o PDL space widening
29. Loss of retention
o Sharp surfaces
o Unequal occlusal loads on different part of
o Contaminating cementing procedures
o Increased cement space
o Sensitivity to temperatures and sweet
o Patient usually complains of recurring bad taste
which should be differentiated from similar
symtoms caused by poor oral hygiene and
Periodic clinical examination should include, to unseat existing
prosthesis by lifting the retainers up and down while they are held
between fingers and a curved explorer placed under connector.
If casting is loose, the occlusal motion causes fluid to be drawn under
casting and when casting is reseated with a cervical force the fluid is
expressed, The examination should be done without drying the tooth.
32. Connector/solder joint failure
Causes of connector failure
o Heavy occlusal forces
o Internal porosity
o Small connector size
Causes of solder joint failure
o Failure to bond to surface of metal
o Improper flow due to decreased width
between joining parts
o Fabrication of new prosthesis.
o Occasionally an inlay like dovetailed preparation can be made on
metal and this casting can be cemented to stabilize the prosthesis.
35. Occlusal wear and perforation
o Heavy occlusal forces
o Clenching, bruxsim lead to
accelerated occlusal wear
o Inadequate clearance
o Attrition of opposing teeth
o Polished facets of the
retainers or pontics
o Gingival recession
o Peroforation of the prosthesis
o If perforation is detected early a restoration can be placed to seal the
o If metal surrounding perforation is extremely thin a new prosthesis
should be fabricated.
o If occlusal surfaces are covered with porcelain, opposing natural teeth
shows dramatic wear of enamel, so go for metal crowns to minimize the
38. Coronal tooth fracture
o Excessive tooth reduction
o Forcibly seating or removing the fixed
o Preparation mainly containing
o If defect is small it is restored with amalgam, resin
o If defect is big/ large a new prosthesis is fabricated so that it wil cover
the fracture area
o If fracture causes pulp exposure endodontic treatment followed by
post and core is necessary prior to fabrication of new prosthesis.
42. a) CAUSES OF METAL CERAMIC FAILURE:
1) FRAMEWORK DESIGN:
o Sharp angles/ extremely irregular areas will serve as points of
o Overbuilt porcelain unsupported by metal
o Overly thin metal casting
o When the angle between the veneering surface and non
veneering aspect of casting is less than 90degree
46. 5) METAL AND PORCELAIN INCOMPATIBILITY
o In rare instances an alloy and porcelain are found to be truly
incompatible, and successful bonding without loss of veneer/
cracking is impossible.
o Ni-Cr alloy is choice of material for long bridges.
o Fabrication of new prosthesis
o Resin materials are used to rebuild the porcelain form in area where
fracture has occurred.
o If fracture is due to heavy occlusal forces, the contact should be
avoided at the metal ceramic junction and it should be at least 1.5mm
away from the junction.
48. o A more permanent repair is possible when adequate metal
thickness is available.
o If there is any risk of pontic area flexing, porcelain should be
carried on to the lingual side of the pontic to stiffen them
49. SLEEVE CROWN
o When a considerable portion of porcelain is lost from labial/
incisal surface of a retainer or pontic it is often possible to repair
than replace the entire unit.
o The porcelain facing is removed with some of the underlying
metal from the labial surface and incisal third of the palatal
o An impression is taken of this and 2 adjacent units. The technician
is then asked to make metal ceramic crown that will have two
surfaces instead of usual four. This sleeve crown is then cemented
in usual way. If too little porcelain is removed from original unit,
the new sleeve crown will feel slightly bulky.
o Tooth preparation should be adequate but not excessive.
o Minor defects can be restored with resin.
o Severely chipped all porcelain crowns must therefore be replaced
by new crown.
52. TYPES OF CERAMIC FRACTURE:
a) Vertical fracture:-
If tapered finish line is used, restoration contacts the tooth on a sloping
surface resulting in forces that attempt to expand the restoration which are
not well resisted by porcelain, leading to vertical fracture.
53. b) Facial cervical fracture
Fracture often assumes a semi lunar form. Generally occurs with short
preparation form. Inciso-cervical length should be 2/3 to ¾ that of final
restoration. When preparation is short, forces at the incisal edge attempt to
tip the restoration facially and cause cervical porcelain fracture.
c) Lingual Fracture
Result of inadequate tooth reduction (1mm) lingually. Occlusal forces is
directed cervically to cingulum of the preparation, fracture also occurs when
forces are more of shear in nature.
54. Pjetursson et al. performed a systematic review of
the 5-year survival rates of all-ceramic single crowns and
to compare them with the survival rates of metal–ceramic
crowns and to describe the incidence of biological and technical
A total of 34 studies met the inclusion criteria. Based on meta-
analysis, the five-year survival rate for ceramic crowns was
estimated 93.3% compared with 95.6% for metal–ceramic
Clin Oral Implants Res 2007;18(Suppl. 3):73–85.
55. 6) CEMENTATION FAILURES
Causes of cement failure
o Cement selection
o Old cement
o Prolonged mixing time
o Thin mix
o Cement setting prior to seating
o Inadequate isolation
o Incomplete removal of temporary cement
o Thick cement space
o Inclusion of cotton fibers
o Insufficient pressure
56. 7) WEAR AND TEAR
Crown and bridge may fail over a period of time because of wear
and tear and this is usually no body's fault.
57. 8) DESIGN FAILURES:
a)Abutment preparation design
o Taper of preparation :-
o Ideal taper for good retention is 70 with minimum cement in between.
However, it is not possible to achieve this taper clinically without
producing some undercuts/ damaging the adjacent teeth.
58. Length of preparation:-
Minimum cervico-incisal height is that which allows the tooth structure to
interfere with arc of rotation as tipping forces attempts to cause rotation
around a fulcrum located at the finish line on the opposite side of the tooth.
59. Circumferential irregularity
o Circumference of teeth is usually irregular in form and when tooth
is uniformly reduced an irregular shape is formed which enhances
ability of restoration to resist both tipping and twisting forces.
o When tooth encountered is round/ short/ over-tapered intentionally
formed irregularities such as boxes, grooves may be used to produce
areas that interfere with dislodgement of restoration.
60. Occlusal irregularities
o Irregular reduction according to the occlusal plane produces
an corrugated form.
o Aids in resistance to dislodging forces, flat reduction provides
little interference and unnecessary reduces the length of
61. Finish line requirements
Supragingival margins are more acceptable than subgingival as they
aid in proper oral hygiene maintenance. They also reduces pulpal
sensitivity as they are usually in enamel.
62. Structural Durability
Functional cusp bevel: Bevel should be given on maxillary lingual
cusp and mandibular buccal cusp at an angle of 450 to provide space
for adequate bulk of metal in an area of heavy occlusal contact.
63. Inadequate Bridge Design
Include design that are unstable or have few abutment teeth e.g.
Cantilever bridge carrying pontics that cover too long a span or a
fixed movable bridge where again span is too long or abutment teeth
with too little support have been selected.
64. Overprescribed FPD
Dentist may include more abutment than are necessary and fate
usually dictates that it is the unnecessary retainer that fails 1st
and 2nd premolar and 2nd molar included to replace 1st molar or
use of 345 on either side to replace incisors in the upper arch.
65. Marginal Deficiencies:
Positive ledge (overhang):- It is an excess of crown material protruding
beyond the margin of preparation. These are more common with porcelain .
However, it is often possible to correct them without otherwise disturbing the
restoration by grinding and polishing in situ.
Negative ledges:- In a deficiency of crown material that leaves the margin of
preparation exposed with no major gaps between the crown and the tooth. It
is fairly common fault particularly with metal margins. But one that is
difficult or impossible to correct at try in stage.
66. Pontic Design
Tissue contact of pontic:- Extensive area of tissue contact is
cited as major cause of failure. Area of contact should be small
and convex. Mesial, distal, lingual gingival embrasures should
be wide open to allow easy cleaning. Contact between the
pontic tissue should allow floss to be passed from one retainer to
67. Dowel Design:
o If a dowel is used its extension into the root must at least equal the
length of the crown.
o A minimum of 4 mm gutta percha and more if possible should
remain to prevent dislodgement and subsequent leakage.
o To prevent fracture, encirclement of 1-2 mm of vertical axial tooth
should be done.
69. COLOUR MISMATCH
This could be the result of
o Inability to match the patient natural teeth with available porcelain
o Shade selection may have been inadequate.
o Metamerism also leads to poor color match.
o Insufficient tooth reduction / failure to properly apply and fire the
porcelain may have created a restoration that does not match the
shade guide or surrounding teeth.
70. Preoperative view of fractured
porcelain on pontic of 3-unit bridge.
Preparation of the exposed metal
creating undercuts in the metal
Application of metal bonding agent. Application of resin opaquer.
REPAIRING PORCELAIN-METAL RESTORATIONS WITH
72. The most common complications associated with conventional fixed partial
o caries (18% of abutments ),
o need for endodontic treatment (11% of abutments ),
o loss of retention (7% of prostheses),
o esthetics (6% of prostheses),
o periodontal disease (4% of prostheses)
o tooth fracture (3% of prostheses),
o prosthesis/porcelain fracture (2% of prostheses).
J Prosthet Dent 2003;90:31-41.
73. Rinke et al in 2013 conducted a study on prospective evaluation of
zirconia posterior fixed partial dentures for 7 years.
After a mean observational period of 7 years, the survival and success
rates of zirconia-based posterior FPDs were inferior to those published
for metal ceramic FPDs.
Int J Prosthodont 2013;26:164–171.
o Following cementation patient should be instructed in particular oral
hygiene procedures necessary.
o Crown needs brushing and flossing just as a sound tooth, but the
position of margin and particular need for care in cleaning should be
demonstrated to the patient.
75. o In case of high decay rate/ decreased salivary flow, dietary advise should
be given and use of fluoride rinses (0.05%) encouraged.
o In bruxers suitable bite appliances should be given.
79. REVIEW APPOINTMENTS:
Restoration is examined with a sharp probe to detect any deficiency,
mobility of the tooth.
If mobility is seen without de-cementation the presence of periodontal
pocket should be determined and occlusion checked, where excessive
loads are the cause.
Bleeding on probing, loss of attachment indicate active disease and
patient should be encouraged for better cleaning.
Periodic radiographs is essential in patients with high risk of dental
Failures in FPD construction for the most part is due to
attempted short cuts or positive indifference and inexcusable
ignorance on the part of those concerned with building the
prosthesis. Also an FPD can just wear out and this cannot be
called as failure as no lifetime guarantee can be given.
The fundamentals of fixed prosthodontic therapy modality have
to be followed strictly, failure of which will lead to the failure of
the prosthesis itself.
o Rossenstiel –textbook fixed partial dentures
o Dykema R.W., Goodacre C.J. and Phillips R.W. “Johnston’s Modern
Practice in Fixed Prosthodontics”. Fourth Edn, W.B. Saunders Co.
o Brown M.H. “Causes and prevention of fixed prosthodontic failures”.
J. Prosthet. Dent. 1973; 30: 617-622.
o Barreto M.T. “Failures in ceramometal fixed restoration”. J. Prosthet.
Dent. 1984; 51: 186-189.
o Charles et al, clinical complications in fixed prosthodontics, J Prosthet
82. o Pruden K.C. “Abutments and attachments in fixed partial dentures”. J.
Prosthet Dent. 1957; 7: 502-510.
o Burke E.J.T. and Grey N.J.A. “Repair of fractured porcelain units:
alternative approaches”. Br. Dent. J. 1994; 176: 251-256.
o Chung K.H. and Hwang Y.C. “Bonding strengths of porcelain repair
systems with various surface treatments”. J. Prosthet. Dent. 1997; 78:
o Walten J.N., Gardner F.M. and Agar J.R. “A survey of crown and
partial denture failures: Length of service and reasons for
replacement”. J. Prosthet. Dent. 1986; 56: 416-421.
o Heintze SD, Rousson V. Survival of zirconia- and metal-supported
fixed dental prostheses: a systematic review. Int J Prosthodont
83. o Kenneth j. anusavice. standardizing failure, success, and survival
decisions in clinical studies of ceramic and metal–ceramic fixed
dental prostheses replacement. Dental material 2012 ;28: 102–111
o John joy manappallil. classification system for conventional
o crown and fixed partial denture failures. j prosthet dent 2008;99:293-
o Pjetursson be, sailer i, zwahlen m, hammerle ch. a systematic review
of the survival and complication rates of all-ceramic and metal–
ceramic reconstructions after an observation period of at least 3 years.
part i: single crowns.
o clin oral implants res 2007;18(suppl. 3):73–85.
o Raigrodski, contemporary materials and technologies for all-ceramic
o dentures: a review of the literature, j prosthet dent 2004;92:557-62