Glass polyalkenoates

Question 1

what is glass polyalkenoate formerly called?

Answer 1

glass ionomers

Question 2

glass polyalkenoates generally contain what?

Answer 2

powder: sodium aluminosilicate glass and CaF
polyacid

Question 3

glass polyalkenoates have a composite structure explain

Answer 3

silaceous hydrogel with unreacted glass cores floating about

Question 4

what kind of reaction is the setting reaction of glass polyalkenoates?

Answer 4

acid base -> salt

Question 5

what are the 2 phases in the setting reaction of glass polyalkenoates?

Answer 5

initial set - first few minutes
final set - about 24hrs after completion

Question 6

what is the structure of a glass particle in glass polyalkenoate

Answer 6

Question 7

at the initail set of glass polyalkenoates what ion predominates? why?

Answer 7

Ca+ ion
as more accessible on the outer surface of the glass particle
and
Ca+ is more mobile than Al3+
Ca+ only cross-links with 2 chains but Al3+ cross links with 3 chains

Question 8

what ion perdominates in the final set of glass polyalkenoates?

Answer 8

Al3+

Question 9

glass polyalkenoates are not fully set until after 24hrs. they are moisture sensitive until final set, what do dentists thus do?

Answer 9

apply a varnish or unfilled resin

Question 10

positives of glass polyalkenoates

Answer 10

adheres to tooth substance
tooth coloured and translucent
fluoride uptake and release

Question 11

negatives of glass polyalkenoates

Answer 11

brittle and relatively poor abrasion resistance
susceptible to acid erosion

Question 12

what are the uses of glass polyalkenoates?

Answer 12

restorative
luting (e.g cementing in crowns)
lining/base

Question 13

how does glass polyalkenoate bond to tooth substance?

Answer 13

bonds with Ca+ ions
bonds with collagen through H bonds and metallic ion bridging

Question 14

how can the bond strength of glass polyalkenoates be increased by prepping the tooth?

Answer 14

apply citric acid -> removes the smear layer
apply polyacrylic acid -> slightly etch tooth surface

Question 15

what are cermets composed of?

Answer 15

mixture of glass and metal particles
introduction of silver

Question 16

positives of cermets

Answer 16

radiopacity
some fluoride release
increased compressive strength
increased fatigue limit

Question 17

negatives of cermets

Answer 17

poor appearance

Question 18

what does modified composite consist of?

Answer 18

filler in composite replaced with aluminosilicate glass to encourage fluoride release

Question 19

what is the setting reaction type for modified composite?

Answer 19

light cured free radical polymerisation

Question 20

what do giomers consist of?

Answer 20

same as modified composite but aluminosilicate glass is prereacted with polyacid to form prereacted polyalkenoate complex

Question 21

what are the two types of giomers?

Answer 21

surface reaction
full reaction

Question 22

what type of setting reaction is giomers?

Answer 22

VLC free radical polymerisation

Question 23

in RMGIC what is the purpose of methacrylate resin?

Answer 23

enables setting by polymerisation

Question 24

in RMGIC what is the purpose of polyacid?

Answer 24

reacts with glass by acid base reaction

Question 25

in RMGIC what is the purpose of HEMA

Answer 25

enables resin and acid components to coexist in aqueous solution

Question 26

in RMGIC what is the purpose of water?

Answer 26

essential for ionisation of acid/base reaction

Question 27

what happens to RMGIC in the presence of water?

Answer 27

expand

Question 28

learn