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Dental Materials > Test #2-3 > Flashcards

Test #2-3 Flashcards

1
Q

What are the requirements of impression material

A 
ease of manipulation
resonable cost
adequate viscosity properites
safety
pt acceptance
compatability with die
adequate shelf life
appropriate setting time
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2
Q

what should be the mechanical strength of impression materials

A

should resist tearing and permanent deformation during removal

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3
Q

what is an important requirement of imp material

A

dimensionally accurate

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4
Q

when are impressions used during fixed restorations

A

crowns, bridges, inlays, onlays, study models

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5
Q

what are impressions used for in removable appliances

A

pediatric, ortho appliances, dentures, partials, study models

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6
Q

what are impressions used for in esthetic appliances

A

bleaching trays, temporary partials

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7
Q

what is rigid

A

unable to remove from undercuts

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8
Q

what is flexible

A

capable of removal from undercuts

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9
Q

what is a hydrocolloid

A

a colloidal suspension in which water is the liquid*

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10
Q

what is a colloid

A

substance dispersed evenly throughout another substance * liquid/solid/gas

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11
Q

agar

A

organic hydrophilic colloid extracted from seaweed

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12
Q

what are reversible hydrocolloid steps

A
  • advanced prep of material
  • prep immediately before impression
  • impression
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13
Q

what are the components of a reversible hydrocolloid

A

agar, thixotropic materials, structure, thickness

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14
Q

What is an example of a irreversible hydrocolloid*

A

alginate

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15
Q

what are alginate impressions accurate enough for

A

study models, working casts, pt education , bleach trays, essex trays, temps

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16
Q
  • what can alginate not be used for
A

-to fabricate indirect restorations

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17
Q

can alginate be softened after setting

A

no

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18
Q

what is imbibition*

A

taking on water

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19
Q

what is syneresis*

A

shrinkage

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20
Q

what does warm water do to alginate*

A

accelerates reaction

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21
Q

what does cold water do to alginate*

A

slows reaction

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22
Q

how does alginate set

A

by chemical reaction

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23
Q

what are inelastic/rigid impression materail

A

plaster, compound, ZOE

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24
Q

What is ZOE used for*

A

impressions, bite registration, perio dressings, temp cements, temp restorative materials

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25
Q

When can you use a rigid/inelastic impression compound

A

for single tooth impressions

26
Q

What is the viscosity of a flexible elastomeric-rubber base impression material

A

light body (low viscosity, better flow/detail)

27
Q

When is regular body elastomeric used

A

when detail is not critical

28
Q

when is heavy body elastomeric used

A

for the bulk of the tray-stability

29
Q

how is the elastomeric impression material packaged

A
  • 2 tubes: light, medium, heavy body
  • cartridge
  • disposable pouches
  • putty
30
Q

how many types of rubber bases are there

A

4

31
Q

what is a polysulfide rubber base*

A

catalyst is lead-hazardous
oldest rubber base
sulfur- bad odor

32
Q

what is a polyether rubber base

A

shortest working time
can pour repeatedly in 24 hrs
irritates skin
poor tear strength

33
Q

what are condensation silicone rubber bases

A
  • base dimethyl siloxane
  • catalyst- tin octoate
  • gives off water/shrinks
  • less flexible than addition silicones
34
Q

what are addition silicone rubber bases

A

polyvinylsiloxane
most popular and most costly
no shrinkage as it sets

35
Q

what are some qualities about addition silicones

A

more accurate and stable
tasteless odorless colorless
doesnt stain clothes
quick and easy to mix

36
Q

gypsum

A

calcium sulfate, mined from the earth and processed

37
Q

what is gypsum used for

A

models, indirect and direct restorations, mouth guards, bleach trays

38
Q

what are models

A

replicas of hard and soft tissue for study

39
Q

what are casts

A

working replicas of hard and soft tissues for use in the fabrication of appliances or restorations

40
Q

what is a die

A

working replicas of one or more teeth used for fabrication of a restoration

41
Q

what is an expoly die*

A
  • resin molecule

- made by mixing epoxy material and forcing into the impression

42
Q

what is electroplating*

A

metal plating by electrolysis, plated to form metalized working dies

43
Q

what is electrolysis*

A

the decomposition of a substance by passage of an electric current through it

44
Q

What is made from calcium dyhydrate*

A

all gypsum products, plaster and stone

45
Q

when calcium hemihydrate powder is mixed with water for impression it reacts with the hemihydrate it then ________________*

A

reverts back to a dihydrate

46
Q

What color is plaster

A

white

47
Q

What kind of particles does platster have

A

porous irregularly shaped particles

48
Q

what color is dental stone

A

buff or yellow color

49
Q

what are the particles like in stone

A

denser more regular shaped particles

50
Q

What color is die stone

A

pink, green , blue or yellow

51
Q

What are factors that determine properties of gypsum products

A

size, shape, and porosity of the particles

52
Q

what are the desireable qualities of gypsum products

A

accuracy, dimensional stability, fine detail, strength and resistance to abraision, ease of adaption

53
Q

waht kind of reactions do gypsum products have

A

*exothermic

54
Q

** what is the written mixing reaction

A

calcium sulfate hemihydrate (plaster/stone)-calcium sulfate dihydrate (gypsum)+ heat

55
Q

what does extra water do to the setting time of model and die materials

A

increases the setting time

56
Q

**When you increase the temp of the water for model and die materials what happens? decrease the temp?

A
  • faster setting

- slower setting

57
Q

*what can decrease the setting time of model and die material

A

potassium sulfate

58
Q

*what can increase the setting time of model and die material

A

borax

59
Q

What is type 1 plaster and stone*

A

impression plaster

60
Q

What is type 2 plaster and stone*

A

model plaster

61
Q

What is type 3 plaster and stone*

A

laberatory stone

62
Q

What is type 4 plaster and stone*

A

die stone

Dental Materials (6 decks)

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