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Flashcards in Amalgam and properties Deck (60)
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1

What are some advantages of amalgam as restorative material?

inexpensive, easily prepared direct material, margin sealing, longevity

2

What are some disadvantages of amalgam as restorative material?

poor aesthetics, weakening of tooth structure, no adhesive bonding, sensitive to manipulation, brittle, mercury waste

3

What are the two components of dental amalgam?

alloy + Hg

4

What is the mercury/alloy ratio?

0.5 or 1:2

5

What is the weight percent of mercury in an amalgam capsule?

42-45 wt%

6

What factors change the setting process?

composition, shape and size of alloy particles

7

What are the major take aways from the ADA standard No 1 requirement for amalgam?

composition, other elements cannot exceed 0.1 wt%,
small creep and dimensional change, and a high compressive strength

8

What are the major elements of amalgam?

Ag (primary), Sn (secondary), cpper, and zinc

9

What are the three phases the complex structure of the particles possess?

gamma (most important), beta, and epsilon

10

What is characteristic of a filling or lathe-cut?

machined from cast ingot (lump of melted metal)

11

What is characteristic of spherical method of particle making?

molten alloy blown through nozzle

12

How many sizes are typically observed from spherical method?

3

13

Is there a wide range of sizes from lathe-cute?

Yes

14

Why is there a wide range of sizes in lathe-cut?

optimum condensation

15

Do spherical particles that are wetted have a higher or lower mercury:alloy ratio than lathe-cut?

lower

16

At what percent is a product considered high-copper?

>12

17

What is the advantage of high-copper products?

longevity and decreased creep

18

Is zinc-free alloy economically feasible?

No

19

Does zinc help or render machining lathe-cut particles?

it facilitates it and improves corrosion resistance

20

What are the benefits of heat treating alloy for dental amalgam?

eliminates non-uniformity, relieves stress, and lowers for the control of setting time

21

Is there free mercury found after the setting reaction?

No, only found in reaction phase

22

Is gamma 1 or 2 absent in set material?

2

23

What gamma is the major reaction phase in low and high-copper amalgams

gamma 1

24

What is characteristic in the first step of dental amalgam setting reaction?

form gamma 1 & 2

25

What is characteristic of the second step of dental amalgam setting reaction?

disappearance of gamma 2 phase and formation of n' phase

26

Is the setting reaction slower than for HCSS products than LCSS?

yes because of the two-step process

27

At what time is the total dimensional change of dental amalgams limited by ADA standard no.1 ?

24 hours

28

Can the dimensional changes be detected by the unaided eye?

No, the contractions cause microleaks

29

What are the two different setting processes of dimensional changes?

solution and crystallization (precipitation)

30

What is the strongest phase in dental amalgams?

incompletely consumed starting alloy particles (gamma)