Dental Amalgam

Question 1

if a patient is wanting amalgams changed for aesthetic reasons what would you advise the patient?

Answer 1

amalgam fillings are safe

mercury vapour produced on removal

Question 2

when is amalgam the best choice of filling material?

Answer 2

not good moisture control
large occlusal load
not good supragingival enamel margins
large complex restoration

Question 3

what happened in 1833

Answer 3

crawcour brothers brought amalgam to the usa, powdered pennies and mercury - expanded on setting

Question 4

1895?

Answer 4

GVBlack - modern day

67% silver, 27% tin, 5% copper, 1%zinc

Question 5

what is creep?

Answer 5

when amalgam flows out of restoration and becomes proud

occlusal loading causes fractures

Question 6

why was copper added?

Answer 6

improves strength of the set material

reduces creep and corrosion

Question 7

what is the tin mercury phase?

Answer 7

the gamma 2 phase

weakest phase - causes creep

Question 8

what does copper eliminate?

Answer 8

eliminates the tin mercury phase

no expansion

Question 9

what does zinc act as in amalgam?

Answer 9

a scavenger

takes up O2 from oxidisation and is easily removed

Question 10

what happened in the 1960’s?

Answer 10

conventional low copper alloy was lathe cut

= admixture - 1st gen of high copper alloy = spherical AgCu

Question 11

1970’s

Answer 11

first single composition spherical

Question 12

1980’s

Answer 12

sim to 1970’s

Question 13

90’s?

Answer 13

first mercury free alloy - gallium

Question 14

problems with mercury free alloy?

Answer 14

increased corrosion and excessive post setting expansion

Question 15

what kind of amalgams are available today?

Answer 15

low copper alloys, admixed high copper alloy, single composition high copper alloy

Question 16

why is amalgam encapsulated?

Answer 16

reduce hg contamination

Question 17

what are the benefits of amalgam being resin free?

Answer 17

no allergies

Question 18

why is saliva control necessary?

Answer 18

water contamination causes expansion on setting

Question 19

what does carving remove?

Answer 19

weak gamma 2

Question 20

how can amalgam be manipulated?

Answer 20

trituration, condensation, burnishing, polishing

Question 21

what happens during overtrituration?

Answer 21

hot mix - sticks to capsule
reduced working and setting time
increase in contraction

Question 22

what happens during undertrituration?

Answer 22

grainy, crumbly mix produced

Question 23

what condensers are beneficial for lathe cut? spherical cut?

Answer 23

small

large

Question 24

what are the benefits of burnishing pre carve?
post carve?
combined?

Answer 24

• removes excess mercury, improves margin adaption
• improves smoothness
• less leakage

Question 25

when to polish and why?

Answer 25

after 24 hours | increase smoothness, reduce plaque retention, reduce corrosion

Question 26

when to bond an amalgam?

Answer 26

gives retention when there is no retention form missing cusp gives good marginal seal

Question 27

advantages of bonding?

Answer 27

dont need pins, reduced marginal leakage and post op sensitivity, reinforcement of tooth structure

Question 28

disadvantages of bonding?

Answer 28

time consuming, expensive, no long term data on efficacy

Question 29

before using smartchem/rely x what do you apply?

Answer 29

line cavity with vitrebond

Question 30

where does toxicity from amalgam arise from?

Answer 30

from the mercury

Question 31

what can happen if the pt has an allergy to amalgam?

Answer 31

contact dermatitis, oral lichen planus

Question 32

what is the potential threat to pregnant women with amalgam?

Answer 32

mercury can cross the placenta