Restoration failure

1. Under supervison :
Dr. Muneera Ghaithan

2. o Definition
o General Causes of Failure
o Failure of Dental Amalgam
o Failure of Dental Composite
o Conclusion

4. The criteria of success of a dental restoration
include :
 Restoration remains integral and in place.
 Absence of recurrent Caries.
 Marginal accuracy and adaptation.
 Perfect aesthetics.
 Maintain perfect anatomy and relations with
neighboring and opposing teeth and periodontal
Structures.
 Patient comfort and satisfaction.

5. Causes of failure can be listed as either
inherent factors or induced factors :
1- Inherent Factors
 Tough conditions in the oral cavity:
 Different Types of Stress.
 Temperature fluctuations.
 PH Cycling.
 Humidity.
 Micro-organisms.
 Shelters and stagnation areas

6. 2- Induced Factors
 Misjudgment in selecting the correct
restorative material.
 Incorrect design of cavity preparation
 Imperfect manipulation of the restoration.

8. Usually amalgams lasts for about 10 years
“linical failure is the point at which the
restoration is no longer serviceable or at
which time restoration posses other
severe risk if it is not replaced”
Failures in amalgam restoration are not
usually because of poor material
Everything done from time of cavity
preparation until restoration is polished
has a definite affect on the restoration

9. At visual At the Pain following Pulp and/or
microstrutural amalgam periodontal
level level restoration involvement
Secondary Corrosion and
caries tarnish
Marginal Stresses
associated
fracture
with
masticatory
forces
Bulk fracture
Tooth fracture
Dimensional
change

10. Failures due to faulty case selection
Failures due to faulty cavity preparation
Failure due to poor matrix adaptation
Failures due to faulty amalgam manipulation

11. 1 Failures due to faulty case selection
 Extensive occlusal caries
 Wide open contacts
 Dissimilar metals

12. 2 Due to faulty cavity preparation
 Greatest single factor for failure
 Healey & philips (1949)
* 56% - cavity
* 42% - manipulation
 Faulty cavity preparation  recurrance of
caries and fracture

13. During cavity preparation the failure occuar at various step :
A-Inadequate occlusal extension :
inadequate extension to pits and fissure increase
chance of caries recurrence particularly in high caries
risk individuals
B-Inadequate extension of proximal box :
If inadequately extended into embrasures, they are not
amenable to brushing and cleaning by mastication 
secondary caries.

14. C-Overextension of cavity preparation walls :
Ideal faciolingual width of cavity is ¼ of intercuspal
distance
If the width is more than ½ ,capping should be
considered
If width more than 2/3, capping is a must
Chance of fracture because restoration act as wedge
and tend to split opposing cusps apart
During capping there should be an amalgam thickness
of 2mm on functional and 1.5mm over non-functional
cusps

15. D-Amalgam cavity should have minimum depth :
of 1.5mm to provide it bulk and hence resistance to
fracture
E-If pulpal floor is not flat :
Restoration produces wedging effect  fracture of tooth
F-Cavosurface angle  butt joint
If acute  tooth fracture
If obtuse  collapse of marginal amalgam

16. G-inadequate proximal retention form / narrow isthmus
fracture at isthmus portion
H-extensive mesio-distal extension
undermining of marginal ridge enamel  fracture
I-incomplete removal of carious tooth material
failure of amalgam restoration

17. 3 DUE TO POOR MATRIX ADAPTATION
Proper contacts and contour in restoration
obtained by matrix
Instability of matrix  distorted restoration,gross
marginal excess and uncondensed soft amalgam
with voids
Cervical excess can result in periodontal irritation
destruction of periodontium

18. 4 DUE TO FAULTY AMALGAM
MANIPULATION
1- Mercury alloy ratio :
 if residual mercury is in excess of 55% loss of
strength
 Under trituration  soft powdery non- coherent mix
 Over trituration  break already formed matrix

19. 2- Condensation :
to ensure amalgam reach all parts of the preparation
and obtain homogenous restoration devoid of voids
Larger cavities  multiple mix should be used to get
homogenous restoration
Small increments should be used to ensure proper
condensation
Mechanical condenser should be used with caution
as it would cause fracture of enamel margins

20. 3- Contamination :
Moisture contamination can occur during
- trituration
- mulling
- condensation
Weaken the restoration especially if zinc containing
It result in marginal flaws, tarnish, pitting, corrosion,
and blistering. Expansion may also lead to pain

21. 4- Finishing and polishing :
Amalgam should be finished gently
Excess spur like overhangs or thin flakes of amalgam
on margins can fracture easily which can leave
crevices in vulnerable areas
Polishing should be done judiciously, temperature
above 65 0c leads to release of mercury leading to
deffective restoration

22.  Appropriate depth and retention form must be generated
 If necessary, another matrix must be placed
 A new mix of amalgam can be condensed directly into
the defect and will adhere to the amalgam already
present
 If the amalgam has been bonded, carefully condition and
apply adhesive to the exposed tooth structure in the
preparation

24. 1. Incomplete removal of carious lesion
2. incomplete etching or incomplete removal of residual acid from
tooth surface
3. Excess or deficient application of bounding agent .
4. Lack of moisture control .
5. Contamination of composite with finger / saliva .
6. following bulk placement technique during polymerization of
composite .
7. Improper polymerization method .
8. Incomplete finishing and polishing of composite .
9. Inadequate occlusion of restored tooth .

25. Following failures are commonly seen in composite
restoration with time :
Discoloratin
Accumulatio Secondary
n of plaque caries
Loss of Gross
fracture of
contact restoration
Fracture of Postoperate
margins sensitivity

26. Marginal defect in composite restorations can be occur
in the following forms :
1 Surface fracture of excess material
2 Voids in restoration because of air
entrapment during placement
3 Composite wear resulting in progressive
exposure of axially directed wall
4 Gaps formation

27. 1. The tooth preparation should be kept as small as possible since
composite in bulk lead to failure .
2. Avoid sharp internal line angles ,which increase stress
concentration.
3. Deeper preparation should be given base of CA(OH) or GI cement.
4. Strict isolation is to be followed.
5. Avoid inadequate curing ,since it lead hydrolytic breakdown of
composite.
6. Use small increments, holding each increment with Teflon coated
instruments.
7. Fill proximal box separately and create proper contact areas .
8. Composite ,especially at beveled areas ,should be finished and
polished properly.

28. Restoration is indicated for replacement when
any of following occurs :
 Secondary caries which cannot be removed during repair
procedure.
 Need for aesthetics.
 Presence of pulpal pathology

29. If a patient presents with a composite
restoration that has a localized defect
• Easily accessible areas may be
roughened with a diamond
stone
• the area is etched; primer may
be applied if dentin is exposed
• adhesive is applied
• finally the composite is
inserted, contoured, and
polished

30. If the defect is not easily accessible
• a tooth preparation must be
created that exposes the
defective area and a matrix
may be necessary
• placement of the etchant,
primer, adhesive
• composite is then performed

31. If a void is detected
• more composite can be added directly
to the void area These materials will
bond because the void area has an
oxygen-inhibited surface layer that
permits composite additions.
• If, however, any contouring has
occurred, the oxygen-inhibited layer
may been removed or altered and the
area must be re-etched and adhesive
placed before adding more composite

32. 1. The criteria of success of a dental restoration
include many factor
2. Causes of failure can be listed as either
3. inherent factors or induced factors
4. Failures in amalgam restoration are not usually
because of poor material
5. During cavity preparation the failure occuar at
various step
6. The tooth preparation should be kept as small as
possible since composite in bulk lead to failure
7. Composite ,especially at beveled areas ,should be
finished and polished properly.