Resin Based Composite vs Amalgam

Question 1

Aim initial restoration?

Answer 1

Eliminate problem w/ no further tx being required

Arrested lesion and total disease control

Question 2

Problems see with restorations?

Answer 2

Structural degradation
Fatigue effects
Change in physical properties
Secondary dsiease

Question 3

What is restorative cycle?

Answer 3

Restoration failure = replacement = further loss of tooth

Question 4

Cause of structural degradation?

Answer 4

Due function and parafunction

Occlusal laoding
Stress-induced parafunction
Loss proprioception

Question 5

Why is the mouth an unfavourable environment?

Answer 5

Environment full bacteria
Temperature changes - cyclic
Variable pH
Bacterial biofilm

Question 6

What want do avoid cyclic changes due variable temperature?

Answer 6

Want coefficient of thermal expansion of material to be similar to tooth

Question 7

Issue w occlusal loads on restored cusps?

Answer 7

Axial load can be translated into lateral force = cusp fracture

Question 8

What are the evidence levels?

Answer 8

Systematic review and meta-analysis
RCT
Cohort studies
Case controlled study 
Case series
Case report
Opinion - expert

Question 9

Annual failure rate of posterior stress-bearing restorations? Diff amalgam and composite?

Answer 9

Amalgam = 3%
Composite = 2.2%

Question 10

Principle reason of failure of posterior restoration?

Answer 10

Secondary caries
Fracture
Marginal deficiency 
Wear
Post-op sesitivity

Question 11

Most common reason for failed amalgam restoration?

Answer 11

Tooth fracture > secondary caries > loss restoration > restoration fracture

Question 12

Most common reason for failed composite?

Answer 12

Restoration fracture > secondary caries > restoration loss > tooth fracture

Question 13

In study of longevity of amalgam vs composite what are results?

Answer 13

No difference survival at 12 years

Amalgam slightly higher failure rate

Question 14

Adv of composite > amalgam in early carious lesions?

Answer 14

Smaller cavities required for composite

Question 15

What factors affect polymerisation shrinkage strain?

Answer 15

Speed and intensity of activation
Ratio of free to bonded surface area
Congifuration factor and volume of composite
Elastic modulus of resin composite

Question 16

What is C-factor?

Answer 16

More enclosed the material is - the greater the stain on interface walls

C= constraining walls/ free surface

Question 17

C factor of class II restoration?

Answer 17

Bonded 4 walls and amount of unbonded surface is 2 = C factor = 4/2 = 2

Question 18

What does number of C factor mean ?

Answer 18

Higher C factor = increased stress

Question 19

What restorations have highest C factor?

Answer 19

Class V

Question 20

How overcome polymerisation shrinkage?

Answer 20

Increased filled load
Modify clinical placement
Flowable - lower filled but elastomeric

Question 21

Adv of composite > amalgam when preparing tooth?

Answer 21

Reduced need for prep

Tooth strong when composite used

Question 22

Future of amalgam?

Answer 22

Phase out use and eventually eliminate use of mercury therefore amalgam

Question 23

What convention related to phased out use amalgam?

Answer 23

Minemata

Question 24

Measures taken at minemata convention on mercury?

Answer 24

Improve caries prevention
Minimise use of amalgam
Promote cost effective alternative/ mercury free alternative
Encourage promotion mercury free material
Discourage program/ insurance policies favouring amalgam