use and hazards of amalgams

Question 1

What is a high copper amalgam?

Answer 1

> 30% copper

Therefore less silver

Question 2

What are useful properties?

Answer 2

Good compressive strength
Good balance of working/setting times
Fair resistance to marginal leakage
Minimal dimensional change when set
Pretty resistant to contamination
Low cost 
200yrs of development

Question 3

What are limitations to amalgams?

Answer 3

Not adhesive
Brittle in thin sections
Composition critical
Detectable levels of creep
Corrosion can weaken
Affected by water during setting
Toxic components
Unaesthetic 
No minimal intervention

Question 4

What are indications for amalgam?

Answer 4

Posterior teeth
When too late for prevention
Adhesive not indicated (occlusal load, size, isolation from moisture)

Question 5

What is Blacks cavity design 1897?

Answer 5

Retention- via mechanical lock w undercut, occlusal lock and more

Resistance to occlusal forces- 2mm thick at least, no deaths edges, cavosurface angle 90 degrees, smooth internal angles, effects of creep- (floor perpendicular to occlusal forces)

Question 6

What are hazards?

Answer 6

Mercury- neurotoxic, affects renal function, cumulative in body and environment

Alloy components- tin and silver- hazardous to environment

Question 7

What is the risk assessment?

Answer 7

PPE- mask and gloves
Rubber dam- protects oral cavity and airway
Avoid in pregnancy
Use capsules which reduces exposure and optimises trituration
High volume suction
Proper disposal
Prevention of caries
Adhesive restorations when possible

Question 8

How do you ensure that the cavity is well isolated?

Answer 8

Free of debris
Dry but not desiccated
Isolated to- maintain dryness, minimise loose material

Question 9

How do you triturate the amalgam?

Answer 9

Capsule in amalgamator in a plastic tray for 10s

Question 10

How do you finish amalgam?

Answer 10

Wait 24hrs
Adjust occlusion and morphology
Reduce corrosion
Aesthetics
Might release mercury vapour so not indicated