GIC

Question 1

What is GIC? And what is it’s concentration?

Answer 1

Glass poly-alkeonate cement
Acid base material = 
base - fluroalumino silicate glass
Acid - poly alkenoic acid
Concentration 40-50%

Question 2

What is the initial matrix

Answer 2

Calcium polyacrylate chains

Question 3

What is the final matrix?

Answer 3

Aluminium polyacrylate chains - less soluble, stronger

Question 4

Uses of GIC

Answer 4

Restorative 
Lining
Luting
Bond between tooth and another restoration 
Temporary restoration 
Sealants
Adhesive for ortho brackets

Question 5

GIC advantages

Answer 5

Chemical bond
Low setting shrinkage 
Good marginal setting
Fluoride release
Favourable pulp response (pulp capping)
Thermal expansion replicates that of tooth
Biocompatible

Question 6

Disadvantages of GIC

Answer 6

Short working time 
Delayed setting time
Water sensitive
Aesthetically inferior to resins
Low strength - fractures easily
Poor resistance to abrasion and wear

Question 7

Setting reaction of GIC

Answer 7

Liquid (acid) attacks glass particles which releases metal ions
Metal ions react with carboxyl (coo) to become (cement) polyacid salt (initial matrix)
Untreated glass remains as fillers
Material clinically sets in a few minutes but there is a maturation phase over the next few months due to the slow reaction of aluminium ions (final matrix)

Question 8

3 phases of GIC setting

Answer 8

Ion-leaching phase (shiny)
Hydrogel phase (rigid and opaque)
Poly salt gel phase

(See lecture notes)

Question 9

Bonding mechanism of GIC

Answer 9

Bond chemically to dentine and enamal. Freshly mixed GIC displaces PO4 and Ca ions from hydroxyapatite and absorbed by unset GIC = ion exchange layer.
See lecture notes

Question 10

Resin modified GIC

Answer 10

Powder - fluroaluminosilicate glass particles with initiators for light curing
Liquid - water and polyacrylic acid modified with methacrylate and hydroxyethyl methacrylate (HEMA) monomers

Light curing causes polymerisation of methacrylate groups. Slow base reaction responsible for maturation and final strength

Question 11

Difference between dentine conditioner and cavity conditioner?

Answer 11

Dentine-mild polyacrylic acid 10% (20secs)

Cavity - mild polyacrylic acid 20% (10secs)

Both remove smear layer, open dentine tubercles, enhances bond