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operative > exam2 > Flashcards

exam2 Flashcards

1
Q

silver

A 
major element
whitens alloy
decreases creep
increases expansion on setting
increases tarnish resistance for the amalagam
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2
Q

tin

A

controlsthe reaction between silver and mercury
reduces the strenghtand hardness
reduces the resistance to tarnish and corrosion
increases the setting time

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3
Q

copper

A

increases hardness and strenght
increases the setting expansion
reduces the marginal deterioration (creep)
reduces the tarnish and corrosion
ties up tin (reducing the gamma-2 formation)

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4
Q

zinc

A

small amount
acts as a scavenger / deoxidizer
without zinc the alloy is more brittle and amalagam formed is less plastic
causes delayed expansion if contaminated with moisture during manipulation
beneficialeffecton corrosion and marginal integration

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5
Q

mercury

A

activates the reaction
only pure metal that is liquid at room temperature
admixed alloys (require more mercury because the lathe-cut particles are more difficult to wet)
spherical alloy (require less mercury due to smaller surface area to wet)

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6
Q

palladium

A

hardens the alloy

whitens the alloy

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7
Q

indium

A

decrease the surface tension
reduces creep on marginal breakdown
increases strenght
must be used in admixed alloys

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8
Q

shapes of the alloy

A

lathe cut
spherical
admixed

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9
Q

material-related variables

A

dimensional change
strength
corrosion
creep

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10
Q

spherical alloys

A

have more contraction
less mercury

strengthen faster

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11
Q

overtrituration causes

A

hot mix - sticks to capsule
decreases working/setting time
higher contraction

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12
Q

strenght after 1 hr

A

40-60% of maximum

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13
Q

strength after 24 hrs

A

90% of maximum

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14
Q

low copper

A

6 months - gamma 2 phase

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15
Q

high copper

A

6-24 months

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16
Q

creep

A

slow deformation of amalgam placed under a constand load; load less than that necessary to produce fracture

gamma-2 dramatically affects creep rate; slow strain rates produces plastic deformation; correlates with marginal breakdown

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17
Q

high copper amalgams

A

have creep resistance
prevention of gamma-2 phase (requires >12% Cu total)
single composition shperical
admixture

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18
Q

undertrituration

A

grainy, crumbly mix

19
Q

lathe-cut alloys

A

small condensers, high force

20
Q

spherical alloys

A

large condensers; less sensitive to amount of force; vertical/lateralwith vibratory motion

21
Q

admixture alloys

A

intermediate handling between lathe-cut and spherical

22
Q

pre-carve burnishing

A

removes excess mercury; improves margin adaptation

23
Q

post-cave burnishing

A

improves smoothness

24
Q

combined burnishing

A

less leakage

25
Q

early finishing

A

after initial set
prophy cup with pumice
provide initial smoothness to restorations
recommended for spherical amalgams

26
Q

amalgam selection

A

copper content >11%
creep <1%
compactability
speed of set

27
Q

high copper advantages

A

high early physical properties (compressive strength, tensile strength, low creep value, high corrosion resistance, minimum Hg/alloy ratio - decrease in residual Hg; variation in setting times that will not affect physical properties)

28
Q

placement steps

A 
mixing
insertion
condensation
precarve burnishing
carving
post carve burnishing
checking occlusion
finishing and polishing
29
Q

reduce residual Hg

A

compaction of amalgam ensures excess mercury moves to the next increment; allows for final amalgam structure to be composed of reinforcing allow the a minimum of reacition product matrix

30
Q

condensation

A

adaption to cavity walls
adaptation of increments toward line and point angles
condenser diameter determines force of condensation
overfill to remove residual Hg
adaptation of increments toward line and point angles (force of condensation adapts amalgam to preparation minimizing leakage at the tooh resotration interface; bisecting line angles, trisecting point angles)

31
Q

nib condenser

A

a new area of amalgam and some of the previously condensed areas; allows for a denser condensation and improved adaption

32
Q

condensation

A

reduction of residual Hg; leads to residual (Not used in alloy reaction) Hg to move to the next layer; always overfill the cavity preparation so that when carving the residual Hg is removed; the overfilled cavity preparation is carved removing the Hg rich layer)

33
Q

burnisher

A

enchances density of amalgam; improves adaptation of amalgam to cavosurface margins; do not over burnish and under contour the restoration

34
Q

purpose of carving restorations

A

define anatomy
remove excess amalgam
return restoration to occlusal function perfect physiologic form and function

35
Q

class II

A

smooth surface lesions found on the interproximal surfaces of posterior teeth; anatomcally the caries initiates in teh enamel apical to the proximal contact; it extends as cone to the DEJ; commonly described as two cones (or triangles) tip to base; once at the DEJ, the bacteria follow the orientation of the dentinal tubules toward the pulp

36
Q

class II pulpal and gingival walls

A

perpendicular to the long axis of the tooth

37
Q

class II axial wall

A

parallel to the long axis of the tooth

38
Q

axial wall contours

A

note the axial wall follow the contour of the external tooth strucutre; teh axial depth is the measurment from the gingival cavosurface margin to the axial wall; this is a horizontal measurement (1.5 mm)

39
Q

primary retetention form

A

smooth, flat pulpal and gingival walls

smooth, parallel or slightly convergent buccal and lingual walls

40
Q

occlusal and proximal boxes

A

must have independent retention

41
Q

occlusal dovetails

A

retentive features

42
Q

bur for retentive grooves

A

placed with 1/4 round bur

43
Q

grooves

A

placed at the expense of the buccal and lingual walls; placed in the axiobuccal and axiolingual line angles; placed entirely in dentin as to not undermine the enamel on the proximal surface of the tooth; follow the contour of the DEJ

operative (2 decks)

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