GIC’s

Question 1

Are GIC hydrophilic or hydrophobic

Answer 1

Hydrophilic

Question 2

What is the Glass?

Answer 2

Calcium-Alumino-Fluoro-Silicate Glass

Question 3

what is the reaction forming GIC?

Answer 3

acid+base reaction
acid = poly acid - usually polyacrylic acid
base = fluoride containing glass

Question 4

Describe the process of the acid and base reaction

Answer 4

DISSOLUTION
- H+ from polyacid, COOH end of glass base
- displace + ions on glass surface
- e.g. Ca2+, Al3+ or F-
= glass has an ion-deficient layer

GELATION
- dispersed ions form bonds with negative COO-
= crosslinking

POST-SET HARDENING
- modified glass surface = polysalt matrix

Question 5

What is the Maturation stage?

Answer 5

= continued formation of the polysalt

the Al3+ ions get displaced
precipitate for up to 24 hrs and at slow pace fo a year

Question 6

what does too much water do to GIC

Answer 6

contamination
increase opacity
reduce hardness and strength

Question 7

why is water important for GIC (4)

Answer 7

water slowly hydrates mature cross-linked matrix
- increase strength
- increase translucency
- increase resistance to dessiccation

Question 8

what does too little water do to GIC?

Answer 8

cause dessication
- crazing and cracking

Question 9

what happens to the calcium free ions?

Answer 9

bond to tooth surface and collagen in dentine through hydrogen bonding

Question 10

what happens to the fluoride free ions

Answer 10

lie free within the matrix and released into surrounding tooth structure

initially released when acid attack - precipitate
slower release over time - remineralisation

Question 11

How do you ensure cross linking happens

Answer 11

use a coating or varnish or bonding resin

Question 12

3 PROS OF GIC - ABCF

Answer 12

Adhesive
Bond to collagen in dentine
Cariostatic
Releases Fluoride

ABCF

Question 13

CONS OF GIC (5)

Answer 13

Technique and moisture sensitive
Can’t take a lot of stress
Low tensile and fracture toughness
Poor wear resistance
Average aesthetic

Question 14

What is the main reason for replacing GIC

Answer 14

secondary caries

Question 15

what is the medial survival time

Answer 15

2.5-3.5 years

Question 16

What is GIC’s biocompatibility

Answer 16

favourable to soft tissue and pulpal response, plaque doesn’t thrive

BUT mild inflammation

Question 17

where do we use GIC (6)

Answer 17

restore primary teeth
class III and V carious lesions
temp dressing
crown repair
cement rigid restorations
as a base under amalgam and composite

Question 18

GIC have replaced cermets, why? (2 pros and 4 cons of cermet)

Answer 18

pros - resistant to acid, adhesive

cons - aesthetics, brittle, prone to abrasion, low coefficient to thermal expansion

Question 19

what are GIC also known as

Answer 19

Glass Polyalkenoate Cement

Question 20

why may viscous GIC’s be favourable (3)

Answer 20

higher powder:water ratio - less water
smaller glass particles
=== more packable and greater strength

Question 20

why may viscous GIC’s be favourable (3)

Answer 20

higher powder:water ratio - less water
smaller glass particles
=== more packable and greater strength

Question 21

how do you improve the adhesion of GIC?

Answer 21

remove the smear layer and clean tooth surface
use dental conditioner (10% polyacrylic acid) aka etching
wash after 20 seconds and dry

Question 22

what is the smear layer

Answer 22

a thin layer of organic and inorganic debris compacted onto dentinal or enamel surface

Question 23

What is Zinc Reinforcements Used and give 2 Uses

Answer 23

higher strength
no varnish or conditioner required

good for long term temp dressing, fissure sealant