Failures in Fixed partial denture for undergraduates

1. FAILURES IN FPD
DR SHRIMANT RAMAN
DEPARTMENT OF PROSTHODONTICS

2. INTRODUCTION
• It is important to analyze failure so that the reasons can be
evaluated and prevention is imparted.
• A fixed partial denture (FPD) can fail as a result of poor patient
care or defective design and inadequate execution of clinical and
lab procedures.

3. CLASSIFICATION

5. Biologic Failure
1) Caries
Secondary caries Interproximal caries on
adjacent tooth
Root caries

6. 2) Pulpal degeneration of Abutment
Improperly directed water
spray
Unrestored abutment / old
restoration with secondary
caries
Properly directed water spray

7. 3) Endodontic failure of Abutment
Inadequate Endo treatment of Ist premolar
causes periapical infections

8. 4)Periodontal failure
 Faulty prosthesis which hinders
maintenance of oral hygiene is due to:
- Poor marginal adaptation.
- Over contouring of retainer axial
surfaces.
- Large connectors
- Pontic contact a large tissue area
- Prostheses with rough surfaces
 Poor maintenance by patient
 Patient with existing periodontal
disease
 lack of abutment support due to
improper plan

9. 5) Tooth perforations
Tooth perforation may have occurred
during:
• Placement of pinholes/pins
• Endodontic treatment
• Preparation for post and core
6) Sub-pontic inflammation
• Refabrication of prosthesis
• Maintenance using floss and
mouth rinse

10. 7) Occlusal problems
8) General pathological conditions –
eg. Squamous cell carcinoma
9) Maintenance failure

11. Mechanical Failure
1) Loss of retention
Causes
• Improper cementation procedure
• Poor retention and resistance form
• Poor fit of casting
• Excessive span length
• Heavy occlusal forces like cantilevers if designed improperly
 If not detected early, a loose retainer can lead to extensive
caries of the abutment.

12. Symptoms
• Patient may perceive a loose retainer as sensitivity to
temperature or sweets and bad taste or odour.
Loose retainer causing bubbles
DETECTION

13. Treatment
• Prosthesis must be removed intact or otherwise. It can be re-
cemented if the reason was a cementation problem and it is
intact.
• If loss of retention is due to preparation design, the teeth should
be modified to improve retention and resistance form and new
prosthesis fabricated.
• If excessive span length is the problem, a removable partial
denture may be the only option.

14. 2) Connector Failure
Causes
• Inadequate connector width if posterior (occluso-cervical), if
anterior (labio-lingual). This is usually due to supraeruption
leaving no space for pontic in height.
• Internal porosity, incomplete casting or soldering which has
weakened the metal can also cause connector failure.
 Treatment

15. 3) Occlusal wear
Causes
• Insufficient thickness of
restoration due to inadequate
preparation of occlusal surface,
lack of functional cusp bevel.
• Heavy chewing forces/bruxism.
• Rough porcelain occlusal
surfaces cause wear of opposing
natural teeth.
Inadequate occlusal preparation

16. 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.

17. 4) Tooth fracture
a) Crown fracture
b) Root fracture
c) Porcelain fracture
- Metal-ceramic(PFM)
- All ceramic

18. Crown fracture
Causes
• Excessive tooth preparation leaving insufficient tooth structure to
resist occlusal forces.
• Endodontically treated abutment without post.
• Abutment mostly comprises of restorative material.
• Interfering centric/eccentric contacts.
• Attempting to forcibly seat an improperly fitting prosthesis.
• Unseating a cemented bridge incorrectly.

19. Root Fracture
Causes
• Improperly designed or a poorly fitting post.
• Root fracture occurring during endodontic or post treatment, but
manifests later.
• Trauma.
• Reduced neural feedback leading to increased loading in endodontically
treated teeth.
Treatment
• Extraction followed by a new prosthesis.

20. Porcelain Fracture
Metal-Ceramic fracture
Causes
i) Improper framework design:
• Sharp angles or extremely rough and irregular areas over coping
surface cause stress concentrations which leads to cracks.
• Perforations in metal.
• Overly thin metal casting does not adequately support the
porcelain.
• Any unsupported porcelain can fracture.

21. ii) Occlusion:
• Heavy occlusal forces like clenching, bruxism.
• Centric or eccentric occlusal interferences.
iii) Metal handling procedures:
• 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. This is caused by improper conditioning of base metal
alloys.

22. iv) During clinical procedures:
• Teeth prepared with slight undercut can cause binding of prostheses
during insertion, which initiates crack propagation.
• Distorted impressions can also cause similar 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.
• Attempts to seat a prosthesis using mallet and wooden stick during try-
in or cementation can crack the porcelain.
• Cleaning fitting surface of prosthesis using ultrasonic scalers can initiate
cracks in the porcelain.

23. All ceramic fracture
• Inadequate finish lines like
feather edge.
• Sharp areas on prepared tooth.
• Large portion of proximal
preparation form is missing and
not restored prior to impression
procedure.
• Round preparation form without
resistance to rotational forces.
• Inadequate lingual tooth
preparation leads to lingual
fracture.
Proximal surface not restored prior to
preparation can cause vertical fracture
of all ceramic restoration

24. Aesthetic Failure
Immediate aesthetic failure
• Inadequate selection and communication
• Metamerism
• Insufficient tooth preparation
• Failure to properly apply and fire porcelain
• Poor tooth contour, gingival contour, pontic ridge contour and
embrasure.
• Poor margin placement.
• Framework design that displays metal.
• Unrealistic expectations of patient due to poor communication.

25. Delayed aesthetic failure
• Gingival recession due to:
- Poor fit
- Overcontour
- Excessive trauma during tooth preparation and impression
making.
Aesthetic failure due to gingival recession

26. • Sub-pontic tissue shrinkage following extraction – if sufficient
time is not allowed for healing following extraction, then the
tissue shrinks after cementation and a gap is formed between the
pontic and ridge which can be unaesthetic especially in anteriors.
• After periodontal surgery – margins will be exposed due to
gingival recession if sufficient healing time is not given following
any surgery.
• Unglazed porcelain can cause unsightly wear of opposing natural
teeth.
• Poorly glazed porcelain restorations also develop black specks
over time.
• Psychogenic failure

27. Methods of removing failed FPD
Back action crown remover
Spring loaded crown
remover

28. • They are all manufactured with different tips to engage
retainers and pontics.
• Other commercial examples include – Richwill, Metalift
and Coronaflex
Pneumatic crown remover

29. Other methods:
• Chisel and mallet
• Cutting retainer : along with crown remover
Carbide bur used to cut the metal
Using a sharp instrument the cut metal is
pried open