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RCD ( Removable complete dentures) > Denture materials > Flashcards

Denture materials Flashcards

1
Q

Whats an intalgio?

A

negative of the cast. Made with impressions

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2
Q

common things were looking for in impression material

A

biocompatible, excellent detail, odorless, tasteless, non-irritating, immune to oral fluids, easy to mix, short working time, disinfectible, good shelf life, cost effective.

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3
Q

3 classifications of impression materials are

A

non-elastic, synthetic elastomers, hydrocolloids.

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4
Q

name some non- elastic materials

A

impression plaster, impression compound, impression waxes

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5
Q

name some synthetic elastomers

A

polysulphides, polyether, silicones

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6
Q

name the 2 types of hydrocolloids

A

reversible, irreversible

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7
Q

Elastomers

A

low molecular weight that increases to become more viscous. Has a base and catalyst and are long crosslinked chains

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8
Q

is thermosetting plastic reversible?

A

no its irreversible

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9
Q

define viscosity and how its tested.

A

resistance to stress, tested by shark fin test

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10
Q

what are the ADA requirements for non-aqueous elastomers?

A

mixing time under 1 min.

working time over 2 min.

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11
Q

does low or high viscosity material catch more details?

A

low

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12
Q

ADA non-aqueous elastomeric materials types 1 &2 detail reproduction must be 20 micrometers while type 3 is what?

A

75 micrometers

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13
Q

type 1 &2 elastic limit is greater than 2.5% but type 3 is what?

A

greater than 6.6 %

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14
Q

maximum change in demension in 24 hr period for types 1 & 3 is less than .5 % while type 2 is

A

less than -1 %

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15
Q

with polysulfides, which group causes chain lengthening and crosslinking by oxidation?

A

SH groups

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16
Q

what causes the mixture to be brown?

A

pbO2, lead oxide

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17
Q

what makes the polysulfide brown paste we used?

A

lead oxide+polysulfide polymer–> larger polysuflide polymer+ water

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18
Q

what are some posittives of polysulfides?

A

elastomeric, flexible, high tear resistance, strong, long working time

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19
Q

what are some negatives of polysulfides?

A

messy, odor, stains clothes, slow setting time

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20
Q

what is the base and catylist in polysulfide impression materials?

A

base- polysulfide

catalyst- lead oxide

21
Q

what is the base in polyether materials?

A

base-polyether polymer, filler/silica, plasticizer/phthalate or glycoesther.

22
Q

what is the catalyst in polyether materials?

A

alkyl aromatic sulfonate, filler and plasticizers, octyl phthalate, 5 % methyl cellulose - thinning agent

23
Q

polyether possitives

A

good tear strength, no water released in reaction, shorter setting time

24
Q

negatives for polyethers

A

absorb humidity( distortion), avoid sun,

25
Q

silicon

A

Si, semi-metal used for electronics

26
Q

Silica

A

SiO2 or silicone dioxide, examples are quartz & glass.

27
Q

silicone

A

polymoers that include Si, C, H, O

28
Q

type 1 condensation silicone materials

A

dimethyl siloxane+ tetra-ethyl orthosillcate= silicone rubber+ ethyl alcohol

29
Q

releasing of ethyl alcohol does what?

A

causes shrinkage, this can be avoided by using 2 step putty wash method

30
Q

type 2, PVS, addition silicone materials.

A

some siloxane+chloroplatinic acid ( a hydrid group)–> silicone rubber ( paladium is added to absorb hydrogens)

31
Q

whats special about type 2?

A

fastest working and setting times

32
Q

what material is used for mucostatic impressions?

A

alginate

33
Q

Historical teeth used in dentures were made of what?

A

human teeth, bovine, hippo teeth, ivory

34
Q

historical bases used in dentures were made of what?

A

hippopotamus ivory

35
Q

porcelain denture teeth

A

mechanically attached ( anterior teeth have pins, posterior have diatoric spaces)

36
Q

traits of porcelain teeth

A

esthetically better than acrylic, more resistant to wear, harder to grind, make clicking noise.

37
Q

Acrylic resin teeth

A

chemically bond to base,fluorescent, various shades, multiple layers, anatomically correct.

38
Q

before 1853 what was used for denture bases?

A

wood, bone, ivory, ceramics

39
Q

after 1853 what was used for denture bases?

A

vulcanized rubber, celluloid which is a nitrocellulose material

40
Q

characteristics of vulcanized rubber

A

formed the base and was unnatural looking, dark reddish brown color

41
Q

characteristics of celluloid

A

formed the gingival area. it was flexible but would absorb stains and develop odors and was flammable.

42
Q

what is PMMA?

A

polymethylmethacrylate resin. This is a acrylate polymer. There is a liquid and powder component that polymerize when mixed.

43
Q

powder portion

A

is the pre polymerized polymer

44
Q

liquid portion

A

non- polymerized monomer

45
Q

what is the polymer to monomer ratio of acrylic polymerization

A

3 polymer to 1 monomer

46
Q

what happens during acrylic polymerization?

A

carbon carbon bonds are created which decreases space and causses shrinkage

47
Q

what is relining a denture?

A

replacing the tissue surface side

48
Q

what is rebasing a denture?

A

replacing everything except the teeth.

RCD ( Removable complete dentures) (9 decks)

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