DOH110 W1

Question 1

What is GIC Composition

Answer 1

Cement powder: Aluminosilicate glass (calcium or strontium) Acidic polymer: Polyalkenoicacid and water

Question 2

What are the GIC 3 stages of setting reaction

Answer 2

Dissolution, Precipitation of Salts (Gelation/Hardening), Hydration of Salts

Question 3

What is Dissolution

Answer 3

The surface layer of the glass is attacked by the polyacid to form a diffusion-based union between the two

Question 4

What is Precipitation of Salts

Answer 4

Calcium/strontium and aluminium ions

bind to polyanionsat the carboxylate groups, Maturation takes place over 24h

Question 5

What is Hydration of Salts

Answer 5

Maturation phase
of the progressive hydration of the matrix salts resulting in sharp improvement of the physical properties takes place up to several days

Question 6

Describe the ability of GIC to bond to a tooth

Answer 6

GIC has the ability to bond chemically to mineralised tissues. Bonds better to enamel than dentine due to greater inorganic content

Question 7

Describe GIC Chemical bonding to tooth structure

Answer 7

Diffusion-based adhesion.

Chemical bonding occurs through combined calcium/strontium phosphate/polyalkenoiatecrystalline structure acting as an interface between both enamel/dentine and the set material.

Question 8

What is GIC Water balance

Answer 8

Auto cure Water in: immediately critical,

Water out: critical for 6m

Question 9

What is RM GIC cements water balance

Answer 9

Water in: less critical for resin-modified and all others, Water out: critical for two weeks for all cements

Question 10

Definition of impression material

Answer 10

An imprint of the teeth and adjacent structures for use in dentistry or mirror image

Question 11

What is Phases 1 Alginate

Answer 11

1st sol◦The material is in a liquid or semiliquid form

Question 12

What is Phases 2 Alginate

Answer 12

2nd gel◦The material is semisolid similar to a gelatindessert

Question 13

Alginate Setting Characteristic phase 1

Answer 13

1. (tri)sodium phosphate + calcium sulphate (allow working time)

Question 14

Alginate Setting Characteristic phase 2

Answer 14

2. remaining calcium sulphate + sodium/potassium alginate

Question 15

Water? Alginate Properties

Answer 15

Water too hot reduces working time sets quicker Water too cold reverse effect

Question 16

Powder &

Alginate Properties

Answer 16

Too much powder thick hard to mix too much water runs out of tray

Question 17

What is Alginate Imbibition

Answer 17

water causes separation of aligned polysaccharide chains leading to swelling of impression

Question 18

What is Alginate Synersis

Answer 18

Water lost by evaporation causing shrinkage

Question 19

What is Alginate strenght

Answer 19

Poor mechanical strength and tears at low levels of stress

Question 20

Reversible Hydrocolloids (agar)

Answer 20

Composition: Supplied in a gel

Question 21

What is Reversible Hydrocolloids (agar) strenght

Answer 21

Properties: Poor mechanical strength and tears at low levels of stress.

Question 22

What is Polysulphides

composition

Answer 22

Two-paste system dispensed from tubes:

Question 23

What are Polysulphides Setting characteristics

Answer 23

chain extension and cross-linkage. Known as condensation polymerization reaction

Question 24

Polyethers

Answer 24

Supplied as two pastes: base and catalyst

Question 25

What is Polyethers Composition

Answer 25

Catalyst paste containing reaction initiator together with paste forming oils and fillers

Question 26

What is the setting time for alginate

Answer 26

1.5 to 3min