Failure of Directly Placed Resotrations

Question 1

Why do we restore teeth? (5)

Answer 1

• To prevent lesions progressing
• Restore occlusion
• Restore function
• Restore aesthetics
• Restore patient comfort and satisfaction

Question 2

How long do restorations last?:

• Survival rate (3)
• Failure rate (3)

Answer 2

• Survival rate:
  Amalgam = 15 years
  Composite = 8 years
  GIC = 30-42 months
• Failure rate:
  Amalgam = 3%
  Composite = 2% (increases to 50% after 10 years)
  GIC = 7%

Question 3

Implications of failed restorations? (5)

Answer 3

• The amount of time spent replacing/fixing it
• The cost spent to replace/fix it
• Material used
• Technique used
• Remaining tooth structure

(Note: If a patient asks you how long a restoration will last, the best answer is ‘I don’t know’. )

Question 4

Why does a restoration fail due to Patient factors? (7)

Answer 4

• High caries risk if the patient’s oral hygiene, diet, dental check ups are poor
• Heavy occlusal forces
• Cavity size and location is awkward and difficult to manage
• Trauma
• Pulpal health
• Periodontal health
• Allergies to amalgam or HEMA in the composite

Question 5

Why does a restoration fail due to Operative factors? (4)

Answer 5

• Incorrect choice of filling material
• Cavity design is poor; lacks retention, weakened cusps, unsupported enamel
• The optimal conditions for the use of a particular filling material have not been reached
• Poor finishing and polishing

Question 6

Why does a restoration fail due to Material factors? (6)

Answer 6

• The material may have undergone thermal expansion
• Compressive strength poor
• Lacks rigidity
• Surface wear poor
• Microleakage may have occurred
• Ditching margin/creep

Question 7

Why does a restoration fail due to Technical factors? (4)

Answer 7

• Fractured restoration
• Margin breakdown
• Tooth fracture
• Defective contours

Question 8

Where does Primary Caries occur? (1)

Answer 8

• At a new site on a restored tooth

Question 9

Where does Secondary Caries occur? (5)

Answer 9

• At the margin
• Under a restoration
• The risk for developing secondary caries is 2.5 times greater with composite restorations compared to enamel
• Caries could have been left behind when the restoration was initially placed
• 60-70% of cases, the adjacent tooth is damaged and therefore it is more likely to develop secondary caries

Question 10

If a restoration has failed, why may there be discolouration over time? (4)

Answer 10

• Loss of marginal integrity
• Marginal staining
• Microleakage of resin restorations
• Loss of surface lustre and polishing

Question 11

What is the main cause of restorations failure? (1)

Answer 11

• Secondary caries

Question 12

How can restoration failure be detected through patient symptoms? (4)

Answer 12

• Pain
• Aesthetic concerns
• Discolouration
• Fracture

Question 13

How can restoration failure be detected through visual inspection? (7)

Answer 13

• Caries
• Marginal breakdown
• Missing restoration
• Fractured restoration
• Discolouration
• Open contacts
• Overhangs

Question 14

How can restoration failure be detected through radiographs? (2)

Answer 14

• Caries

- Periodontal status

Question 15

How can restoration failure be detected through occlusal examination? (1)

Answer 15

• See how the restoration occludes with opposing teeth

Question 16

What are the treatment options with regards to a failed restoration - Repair or Replace? (4)

Answer 16

You should try to repair the restoration, provided there is:

• No signs of gross spreading caries
• Sufficient amount of the restoration is still intact and will withstand masticatory forces
• Able to bond or mechanically interlock the new restoration to the old one
• There will be no obvious difference between the new and old restoration