Denture materials

Question 1

Whats an intalgio?

Answer 1

negative of the cast. Made with impressions

Question 2

common things were looking for in impression material

Answer 2

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

Question 3

3 classifications of impression materials are

Answer 3

non-elastic, synthetic elastomers, hydrocolloids.

Question 4

name some non- elastic materials

Answer 4

impression plaster, impression compound, impression waxes

Question 5

name some synthetic elastomers

Answer 5

polysulphides, polyether, silicones

Question 6

name the 2 types of hydrocolloids

Answer 6

reversible, irreversible

Question 7

Elastomers

Answer 7

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

Question 8

is thermosetting plastic reversible?

Answer 8

no its irreversible

Question 9

define viscosity and how its tested.

Answer 9

resistance to stress, tested by shark fin test

Question 10

what are the ADA requirements for non-aqueous elastomers?

Answer 10

mixing time under 1 min.

working time over 2 min.

Question 11

does low or high viscosity material catch more details?

Answer 11

low

Question 12

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

Answer 12

75 micrometers

Question 13

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

Answer 13

greater than 6.6 %

Question 14

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

Answer 14

less than -1 %

Question 15

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

Answer 15

SH groups

Question 16

what causes the mixture to be brown?

Answer 16

pbO2, lead oxide

Question 17

what makes the polysulfide brown paste we used?

Answer 17

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

Question 18

what are some posittives of polysulfides?

Answer 18

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

Question 19

what are some negatives of polysulfides?

Answer 19

messy, odor, stains clothes, slow setting time

Question 20

what is the base and catylist in polysulfide impression materials?

Answer 20

base- polysulfide

catalyst- lead oxide

Question 21

what is the base in polyether materials?

Answer 21

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

Question 22

what is the catalyst in polyether materials?

Answer 22

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

Question 23

polyether possitives

Answer 23

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

Question 24

negatives for polyethers

Answer 24

absorb humidity( distortion), avoid sun,

Question 25

silicon

Answer 25

Si, semi-metal used for electronics

Question 26

Silica

Answer 26

SiO2 or silicone dioxide, examples are quartz & glass.

Question 27

silicone

Answer 27

polymoers that include Si, C, H, O

Question 28

type 1 condensation silicone materials

Answer 28

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

Question 29

releasing of ethyl alcohol does what?

Answer 29

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

Question 30

type 2, PVS, addition silicone materials.

Answer 30

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

Question 31

whats special about type 2?

Answer 31

fastest working and setting times

Question 32

what material is used for mucostatic impressions?

Answer 32

alginate

Question 33

Historical teeth used in dentures were made of what?

Answer 33

human teeth, bovine, hippo teeth, ivory

Question 34

historical bases used in dentures were made of what?

Answer 34

hippopotamus ivory

Question 35

porcelain denture teeth

Answer 35

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

Question 36

traits of porcelain teeth

Answer 36

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

Question 37

Acrylic resin teeth

Answer 37

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

Question 38

before 1853 what was used for denture bases?

Answer 38

wood, bone, ivory, ceramics

Question 39

after 1853 what was used for denture bases?

Answer 39

vulcanized rubber, celluloid which is a nitrocellulose material

Question 40

characteristics of vulcanized rubber

Answer 40

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

Question 41

characteristics of celluloid

Answer 41

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

Question 42

what is PMMA?

Answer 42

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

Question 43

powder portion

Answer 43

is the pre polymerized polymer

Question 44

liquid portion

Answer 44

non- polymerized monomer

Question 45

what is the polymer to monomer ratio of acrylic polymerization

Answer 45

3 polymer to 1 monomer

Question 46

what happens during acrylic polymerization?

Answer 46

carbon carbon bonds are created which decreases space and causses shrinkage

Question 47

what is relining a denture?

Answer 47

replacing the tissue surface side

Question 48

what is rebasing a denture?

Answer 48

replacing everything except the teeth.