Denture materials Flashcards Preview

RCD ( Removable complete dentures) > Denture materials > Flashcards

Flashcards in Denture materials Deck (48):
1

Whats an intalgio?

negative of the cast. Made with impressions

2

common things were looking for in impression material

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

3

3 classifications of impression materials are

non-elastic, synthetic elastomers, hydrocolloids.

4

name some non- elastic materials

impression plaster, impression compound, impression waxes

5

name some synthetic elastomers

polysulphides, polyether, silicones

6

name the 2 types of hydrocolloids

reversible, irreversible

7

Elastomers

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

8

is thermosetting plastic reversible?

no its irreversible

9

define viscosity and how its tested.

resistance to stress, tested by shark fin test

10

what are the ADA requirements for non-aqueous elastomers?

mixing time under 1 min.
working time over 2 min.

11

does low or high viscosity material catch more details?

low

12

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

75 micrometers

13

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

greater than 6.6 %

14

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

less than -1 %

15

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

SH groups

16

what causes the mixture to be brown?

pbO2, lead oxide

17

what makes the polysulfide brown paste we used?

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

18

what are some posittives of polysulfides?

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

19

what are some negatives of polysulfides?

messy, odor, stains clothes, slow setting time

20

what is the base and catylist in polysulfide impression materials?

base- polysulfide
catalyst- lead oxide

21

what is the base in polyether materials?

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

22

what is the catalyst in polyether materials?

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

23

polyether possitives

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

24

negatives for polyethers

absorb humidity( distortion), avoid sun,

25

silicon

Si, semi-metal used for electronics

26

Silica

SiO2 or silicone dioxide, examples are quartz & glass.

27

silicone

polymoers that include Si, C, H, O

28

type 1 condensation silicone materials

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

29

releasing of ethyl alcohol does what?

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

30

type 2, PVS, addition silicone materials.

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

31

whats special about type 2?

fastest working and setting times

32

what material is used for mucostatic impressions?

alginate

33

Historical teeth used in dentures were made of what?

human teeth, bovine, hippo teeth, ivory

34

historical bases used in dentures were made of what?

hippopotamus ivory

35

porcelain denture teeth

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

36

traits of porcelain teeth

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

37

Acrylic resin teeth

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

38

before 1853 what was used for denture bases?

wood, bone, ivory, ceramics

39

after 1853 what was used for denture bases?

vulcanized rubber, celluloid which is a nitrocellulose material

40

characteristics of vulcanized rubber

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

41

characteristics of celluloid

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

42

what is PMMA?

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

43

powder portion

is the pre polymerized polymer

44

liquid portion

non- polymerized monomer

45

what is the polymer to monomer ratio of acrylic polymerization

3 polymer to 1 monomer

46

what happens during acrylic polymerization?

carbon carbon bonds are created which decreases space and causses shrinkage

47

what is relining a denture?

replacing the tissue surface side

48

what is rebasing a denture?

replacing everything except the teeth.