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Pres/Res > Amalgam Restoration > Flashcards

Amalgam Restoration Flashcards

1
Q

Unique about amalgam longevity

A

Seals more over time due to its corrosion

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2
Q

Percent of allergies to amalgam

A

1%

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3
Q

Contraindications

A

Aesthetic places, small or medium isolated lesions

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4
Q

Advantages of amalgam

A

affordable, easy to use and place

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5
Q

Risk of amalgam

A

not proven

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6
Q

Disadvantages

A

more complex and technical which leads to less conservation of teeth, non-esthetic, potential for galvanic reactions (dissimilar metals and saliva is conductor), potential for marginal breakdown, poor edge strength, non-insulating, negative perception

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7
Q

Edge strength of amalgam

A

Poor

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8
Q

Biocompatibility of amalgam

A

bioinert or mildly irritating

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9
Q

leakage of mercury?

A

No, corrosion seals well

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10
Q

amalgam tatoo or stain

A

mercury that moved to gingiva causes gray color but benign/no histo changes

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11
Q

Thermal irritation

A

possible for amalgam preps placed deep; hot or cold sensativity

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12
Q

Spherical Amalgam

A

atomize liquid alloy; less condensation pressure; high early st. FINISH

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13
Q

Lathe Cut

A

milling or cutting alloy, irregular shaped, more condensation P,proximals

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14
Q

Admixed

A

Properties of both; more P, easier for interproximals, longer working time slower set

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15
Q

Amalgam capsules

A

Upper-liquid mercury
Middle-septum
Lower-alloy powder-contains pestle for mixing

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16
Q

Alloy powder contains

A

Silver, Tin, Copper, some have zinc

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17
Q

Tin in powder

A

highest affinity for mercury

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18
Q

highest affinity to mercury

A

Tin

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19
Q

Reduces oxide formation over time

A

Zinc

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20
Q

Problem of zinc

A

can have delayed expansion in presence of moisture during prep

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21
Q

Conventional Setting Reaction

A

3 phase outcome; finish

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22
Q

dimensional change

A

impacts final adaptation-initial contraction as Hg reacts with alloy and then expansion as setting progresses

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23
Q

increase expansion of amalgam

A

moisture during placement and under trituration

24
Q

reduce expansion

A

inc. trituration time, more P when condensing, use material with reduced mg/alloy ratio

25
Q

Factors affecting material strength

A

trituration, high condensation, no porosity (porosity reduces), sufficient mercury content, excess mercury –> increased gamma 2 phase, hardening rate

26
Q

excess mercury

A

increased gamma 2 phase

27
Q

Sweet spot values for Hg concentration by weight % vary by alloy but normally about

A

50%

28
Q

ADA spec for amalgam hardening

A

amalgam reaches 80 MPa within 1 hour

29
Q

Most amalgam fractures happen when

A

within the first few hours

30
Q

Set in 20 min of almagam

A

only 6%-don’t eat crunchy stuff

31
Q

amalgam reaches 70% by?

A

first 8 hours

32
Q

MArquette type hardening rate

A

187 MPa in 1 hour, 431 by 7 days; dispersalloy admixed

33
Q

survival of amalgam

A

7-15 years on median, larger more complex to the low end, in controlled studies 55-70yrs

34
Q

Amalgam condensation

A

compact the alloy (inc. density and remove voids-excess Hg and water), adaptation to walls, reduce excess mercury

35
Q

Condenser size

A

Small condenser needs less P for larger F while larger needs more P; INVERSE RELATIONSHIP

36
Q

F needed for condensing

A

6-10lbs of force

37
Q

critical factor in amalgam placement

A

condensation

38
Q

Condensation technique

A
  1. overlap and orderly-use small condenser first
  2. overfilling/overpacking-remove with carving
  3. Time (too long=increased voids)
39
Q

When condensing class II

A

condense deepest parts first!!

40
Q

Size condenser to use first

A

Small then large once more full

41
Q

1 min beyond manufacturers recommendation results in ____

A

> 30% increase in residual Hg

42
Q

Goal of amalgam carving

A

reproduce anatomy that results in proper form and function

43
Q

Flash

A

extension of the restorative material beyond the prep margins (prone to fracture)

44
Q

first instrument for carving

A

some kind of burnisher

45
Q

When carving should be initiated

A

before the amalgam has reached its initial set

46
Q

Carve _____ to margins

A

Parallel- want instrument to have support to avoid ditching

47
Q

Grooves are too deep

A

thin amalgam = prone to fracture, the potential for exposure of prep walls, difficult to finish or polish

48
Q

over carving effects

A

soft tissue problems when convexity is lost

49
Q

Smooth at end with

A

Cotton roll

50
Q

dispersalloy regular set (tituration speed, condensation time, set time)

A

tituration speed: turtle, 11-17 seconds
Condensation time: 3:30
Set time: 4:30

51
Q

Brittle consideration of amalgam

A

material is brittle so keep > 1.5 mm

52
Q

When done condensing do not forget to

A

clear the condenser!

53
Q

discard capsules and pessile where

A

in clear containers

54
Q

Amalgam scraps go

A

into amalgam scrap containers

55
Q

T/F; amalgams can be polish right away with a rotary instrument?

A

False; only after 24 hours!!!!

Pres/Res (14 decks)

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