Composite vs Amalgam

Question 1

What occurs when you replace a restoration? (restorative cycle)

Answer 1

Structural degradation = increased stress fields

• Fatigue effects
• Change in physical properties
• Other destructive lesions
• Placement of adjacent restorations
• Direct and indirect loading forces (functional and parafunctional)
• Further loss of tooth structure
• Occlusal loading, reduced occlusal support, stress induced parafunction. 300-500N is the normal masticatory load.
• Environment - variable pH, constantly wet, bac biofilm, temp changed

= Restoration failure

Question 2

How compromised is a restored tooth?

Answer 2

An MOD cavity and/or a passive restoration (non-adhesive (amalgam)) reduces cuspal stiffness by 63%

Question 3

What happens as a compromised tooth ages?

Answer 3

It acquires a payload of environmental, operative and degradation damage that compromises its vitality, structural integrity and long term viability

Question 4

What factors determine the survival of the restoration?

Answer 4

Build quality
Product handling
Environment
Maintenance

Question 5

Highest to lowest system of evidence?

Answer 5

Systematic reviews and meta-analysis - HIGH 
RCTs
Cohort studies
Case control studies
Case series
Case reports
Ideas, editorials, opinions
Animal research 
In-vItro lab research - LOWEST

Question 6

Posterior composite variables?

Answer 6

Tooth status
Occlusal forces
Materials
Variable expertise
Technique
Maintenance

Question 7

Annual failure rates in posterior stress bearing restorations?

Answer 7

Amalgam 3%

Direct composite 2.2%

Question 8

Reasons for failure of restorations?

Answer 8

2ndry caries, fracture, marginal deficiencies, wear and post op sensitivity

Question 9

Most common to least common reason for failed composite?

Answer 9

Restoration fracture 23%
2ndry caries 20%
Restoration loss 17%
Tooth fracture 9.4% LEAST

Question 10

Most common to least common reason for failed amalgams?

Answer 10

Tooth fracture 28%
2ndry caries 20%
Restoration loss 20%
Restoration fracture 15%

Question 11

Opdam NJ et al 2010 - what did this study state on longevity of restorations?

Answer 11

If pt was high/low caries risk based on restorative and caries history, plaque, lesions, motivation
= Composite more likely to survive in low risk pts, amalgam in high risk pts
= No difference in survival between amalgam and resin composite restorations after 12 yrs
= No diff between operators
= Composite failure after 12 yrs 1.68%, amalgam 2.41%

Question 12

Opdam NJ et al 2010 - reasons for restoration failure?

Answer 12

Caries - composite better in low risk pts, amalgam lasts longer in high risk pts
Fracture and cracked tooth syndrome - predominantly with amalgam

Question 13

Opdam NJ et al 2010 - What is the advantage of adhesive restorations?

Answer 13

Smaller cavities for early carious lesions

- Restoration occupies 5% of occlusal surface when composite but 25% in amalgam