Glass Polyalkenoate/Glass ionomer cement

Question 1

What is another name for glass polyalkenoate cement?

Answer 1

glass ionomer cements

Question 2

What are the 2 basic ocmponents of GPC?

Answer 2

glass

acid (usually polyacrylic acid)

Question 3

What type of reaction occurs in GPC?

Answer 3

acid-base reaction

Question 4

Is fluoride released from GPC?

Answer 4

yes, throughout its life

Question 5

What is the liquid component, acid or base?

Answer 5

acid, usually polyacrylic

Question 6

Can glass ionomer cements be light cured?

Answer 6

no, only chemically

Question 7

When can the GIC be light cured?

Answer 7

if resin is in there, but at that point it is not a cement, it is likely a resin modified glass ionomer

Question 8

What is the glass component of the GIC?

Answer 8

fluoro-alumino-silicate

Question 9

Where is the source of fluoride in GIC?

Answer 9

from the glass component,… fluoro-alumino-silicate

Question 10

What is the effect of adding in elements strontium and lithium into glass?

Answer 10

impoact radiopacity

Question 11

What is the effect of altering the aluminium/silica ratio?

Answer 11

make it more translucent

Question 12

What is the effect f altering ion release of the glass?

Answer 12

determines the solubility, setting characteristics and fluoride release

Question 13

What are the main components of glass?

Answer 13

Question 14

What has the highest percentage composition of glass?

Answer 14

silica (silicon oxide)

it does vary though

Question 15

How is the glass made?

Answer 15

glass mixture heated to between 1150 and 1450

molten mass poured onto metal plate and then cooled into water (shock cooling)

broken up to form a glass frit

wet or dry milled to produce small particles of glass

Question 16

What is the max size of particle which can be used for restoration?

Answer 16

20um

Question 17

What is shock cooling?

Answer 17

molten mass is poured onto a metal plate and then into water

Question 18

What is the process called to reducing glass reactivity?

Answer 18

passivation treatment

Question 19

What does passivation treatment involve?

Answer 19

washed with acetic acid for up to 24 hours and then dried

Question 20

What acid is used in passivation treatment?

Answer 20

acetic acid

Question 21

How does passivation treatment reduce the reactivity of glass?

Answer 21

leads to ion depletion of the glass surface - fewer ions immediately available to form the salt matrix at start of mix

Question 22

When is passivation treatment maximised?

Answer 22

it has greater significance when the particle size of cement is reduced (smaller particle size the more rapid the set; volume: surafce area)

Question 23

Polacrylic acid is the main acid in GIC, what are the others in the series?

Answer 23

polymaleic acid

number of copolymers of polyacrylic acid

Question 24

What group is common to all of the acids?

Answer 24

carboxylate

Question 25

Why is the carboxylate common to all of the acids?

Answer 25

as water ionises to carboxyl and hydrogen ions to facilitate chemical reaction facilitate the chemical reaction

Question 26

What can be added to the GIC acid component to sharpen the set?

Answer 26

polyphosphonic acid to provide a short sharp set

Question 27

What does an cement with a higher molecular weight determine?

Answer 27

it will have better mechanical properties

Question 28

What is the disadvantage of the high molecular weight of cement?

Answer 28

higher viscosity and harder to work with

Question 29

How do some manufacturers package the GIC?

Answer 29

vacuum dry the acid solution and then mix the anhydrous powder so formed with the glass activation of the cement is achieved by adding water just adjust the water to powder ratio

Question 30

What can molecular weight of the cement also influence?

Answer 30

the working and setting time higher molecular weight, shorter the working time

Question 31

What acid has been used to facilitate encapsulation of the cement?

Answer 31

maleic acid, makes it les viscous

Question 32

What acid is added to the cement to accelerate setting reaction?

Answer 32

tartaric acid - it maintains the working time

Question 33

What is the structure of the GIC?

Answer 33

Cored structure

Question 34

What is the unreacted powder material (glass) encased in? (after setting)

Answer 34

salt matrix

Question 35

What do the surface soluble components of glass react with?

Answer 35

acid from the matrix

Question 36

What is the setting reaction of GIC?

Answer 36

(DONT NEED TO MEMORISE)

Question 37

What gel forms around the glass particles?

Answer 37

silica gel

Question 38

What come out of the silica gel around the glass core?

Answer 38

calcium, aluminium and fluoride ions

Question 39

What do the calcium, aluminium and fluoride ions form? (form the silica gel)

Answer 39

calcium and aluminium polysalts

Question 40

When does the condensation reaction occur more rapidly?

Answer 40

with the calcium ions

Question 41

What gel the calcium ions form? (condensation)

Answer 41

calcium polyacrylate gel formed- within a minute

Question 42

Why does the aluminium take longer to form polyacrylate gel compared to calcium ions? (condensation)

Answer 42

aluminium ion is triple charges and less mobile

Question 43

What occurs after the polyacrylate gel has formed by condensation?

Answer 43

cement goes through a period of maturation

Question 44

What occurs during the maturation period of setting?

Answer 44

further cross-linking of the matrix and more cations become bound onto the polyanion chain

Question 45

What properties increase during the maturation phase of the setting reaction?

Answer 45

increase in mechanical properties

Question 46

How long can the maturation phase take?

Answer 46

months

Question 47

What is the compressive and flexural strength like of GIC?

Answer 47

relatively low but increase very time as the martial matures (maturation stage)

Question 48

Do you place a protective layer over GIC and why?

Answer 48

yes, varnish can be put over longer the restoration is protected from moisture, better resistance it is to erosion (not good with oral fluids)