Amalgam

Question 1

Dental amalgam is a combination of what 2 things?

Answer 1

liquid elemental mercury & metal alloy

Question 2

Eames’ ratio

Answer 2

half mercury and half metal alloy

Question 3

Alloy contains (4):

Answer 3

silver
copper
tin
zinc

Question 4

alloy that is a provider of strength

Answer 4

silver and copper

Question 5

alloy that is the primary provider of corrosion products

Answer 5

tin

Question 6

alloy that is a deoxidizer

Answer 6

zinc

Question 7

Trituration of amalgam results in 3 phase compositions:

Answer 7

Υ phase = unreacted silver-tin
Υ1 phase = silver-mercury matrix
Υ2 phase = tin-mercury matrix

Question 8

Trituration of amalgam results in 3 phase compositions.
Which is the strongest and least corrosion resistant?

Answer 8

Y phase

Question 9

Trituration of amalgam results in 3 phase compositions.

Which phase is the next strongest and corrosion resistant?

Answer 9

Υ1 phase

Question 10

Which is phase is the weakest and susceptible to corrosion and creep?

Answer 10

Y2 phase

Question 11

properly triturated vs over-triturated vs under-triturated amalgam

Answer 11

Properly triturated = shiny, smooth, easily loaded, reaches peak strength after 24h

Over-triturated = warm, soft, sets quickly

Under-triturated = dry, crumbly, sets quickly

Question 12

In the past, copper composition was low inside of dental amalgam. However with time, more copper was incorporated to provide (3):

Answer 12

more strength
lower corrosion ability
longer marginal longevity

Question 13

low copper vs high copper amalgam

Answer 13

Low copper- contains 12% Cu, yields in the production of Y, Y1, and Y2 phases

High copper- contains over 12% Cu, yields only Y and Y1 phases, with minimum corrosion products and creep

Question 14

2 alloy particle types

Answer 14

spherical and admixed

Question 15

alloy particles that are small spheres, contain more plastic, have a quicker set time, condenses better, and are more durable

Answer 15

spherical

Question 16

alloy particles that contain both spherical and irregular particles, need higher condensation forces, yields better proximal contacts with adjacent teeth

Answer 16

admixed

Question 17

Indications & contraindications for amalgam:

Answer 17

Indications
- bigger preps that require heavier functional loading
- areas that are harder to isolate from saliva
- teeth which serve as abutments
- non-esthetic regions
- preps that extend to root surfaces

Contraindications:
- esthetics zones
- metal allergy

Question 18

commonly used instrument used for occlusal carving of amalgam

Answer 18

Hollenback carver
Cleoid-discoid

Question 19

commonly used instrument for removing excess amalgam on proximal surfaces and carving of the gingival embrasures

Answer 19

amalgam knife

Question 20

commonly used instrument for occlusal embrasure carving

Answer 20

explorer tip

Question 21

Potential reasons why a marginal ridge fracture might occur:

Answer 21

• overbuilt marginal ridge
• axiopulpal line angle not being rounded
• excessive carving leaving less than 2mm of thickness
• incorrect removal of matrix band

Question 22

Class V amalgam restoration preps must demonstrate:

Answer 22

• occlusal divergence due to the enamel rod orientation
• retention features such as gingival or circumferential grooves can be used

Question 23

greatest health risk from mercury toxicity

Answer 23

inhalation (80% of elemental mercury is absorbed through the lungs)

Question 24

how to handle amalgam spills

Answer 24

cover with sulfur powder and cleaned with a special vacuum

Question 25

Acute mercury toxicity can result in (3):

Answer 25

• muscle weakness (hypotonia)
• GI trouble
• loss of hair (alopecia)

Question 26

form of mercury that is organic and highly toxic, exposure can only occur with ingestion of seafood

Answer 26

methylmercury

Question 27

a liquid metallic form of mercury found in dental amalgam

Answer 27

elemental

Question 28

an inorganic form of mercury

Answer 28

mercury salts