GICs 2

Question 1

Describe the powder composition of cermets

Answer 1

• Metal (usually silver) fused to GIC powder then ground into powder together or just mixed with GIC powder (admix)
• Titanium dioxide (5%) might be added to improve the colour

Question 2

Describe the composition and delivery of the liquid component fo cermets

Answer 2

• Same as conventional GIC and can be hand mixed or encapsulated

Question 3

Describe the structure of admix

Answer 3

Silver metal and GIC powder

• Silver = brightest on photomicrograph
• Matrix = PAA GIC
• Glass particles
• Around silver and matrix = gap due to mechanical, not chemical mix

Question 4

Describe the properties of cermets

Answer 4

• More abrasion resistant and less brittle than conventional GICs
• Fluoride release and bond strength are reduced
• Radiopaque
• Difficult to handle

Question 5

What uses are there for Cermets

Answer 5

• Cermet/composute laminate technique
• Linings for amalgam restorations
• Repair of restoratives
• Used where aesthetics aren’t super important as they have a silver colour

Question 6

Describe the liquid composition of Resin Modified GICs (RMGICs)

Answer 6

• PAA + tartaric acid
• Water compatible vinyl monomer, usually HEMA or elements of vinyl monomers will be chemically grafted into PAA as a pendant methacrylate
• Photo-initiator system
• Some Bis-GMA/UDMA

Question 7

Describe the powder composition of RMGICs

Answer 7

• Ion leachable glass
• Photosensitiser
• Similar to conventional GICs

Question 8

What 2 reactions happen in the setting of RMGICs

Answer 8

• Acid base reaction of the glass ionomer cement

- Photo-initiated polymerisation of the monomer

Question 9

Describe the structure of the set cement

Answer 9

Interpenetrating network of the poly salt matrix entangled with poly (hydroxyethyl methacrylate)

Structure is similar to that of a conventional glass ionomer

Question 10

What is the matrix of RMGICs made of

Answer 10

Cross linked polyacrylic acid matrix and polyhema

Question 11

What are the advantages of RMGICs

Answer 11

• Less soluble
• Less brittle
• Can be polished immediately
• Fluoride release is similar or higher than conventional glass ionomers
• Adhesion to tooth
• Compressive strength
• Longer working time an rapid set

Question 12

What are the disadvantages of RMGICs

Answer 12

• Addition of HEMA slows the acid base reaction
• Depth of cure is less than composites because of the reduced light transmission of the filler
• Polymerisation exotherm is higher than composites
• Polymerisation shrinkage
• Swell in water after curing as PHEMA is a hydrogel
• Acid base reaction starts on mixing and if not photo cured quickly the properties might be affected
• Unpolymerised HEMA will leach out resulting in increased cytotoxicity
• Stain
• HEMA, BisGMA and PAA can separate in the bottle

Question 13

What can the tricure RMGIC be cured by

Answer 13

Photo cure
Room temp cure
Acid base cure

Question 14

What chemical components allows tricure RMGICs to set at room temp

Answer 14

Ascorbic acid and potassium persulphate

Question 15

What is the purpose of the tricure RMGIC

Answer 15

To eliminate the need for layering in deep cavities

Reduces Swelling

Question 16

What are the uses of RMGICs

Answer 16

• Cavity lining
• In the GIC composite laminate technique
• As an anterior restorative
• Restorative for deciduous teeth
• Luting cement

Question 17

What is a PAMC

Answer 17

Polyacid modified composite

Question 18

What are PAMCs also called

Answer 18

Compomers

Question 19

Describe the powder composition of PAMCs/compomers

Answer 19

• BisGMA/UDMA + visible light curing system
• Ion leachable fluoroaluminosilicate glass filler + conventional fillers
• Acidic monomer - bifunctional monomer with pendant carboxylic groups
• Hydrophilic monomers may bed added to aid water absorption and fluoride release
• Moisture and light sensitive during storage

Question 20

How does the acidic monomer form

Answer 20

The composite monomer has double bonds and carboxyl groups from PAA are added to the monomers.

Therefore the acidic monomer has both C=C and carboxyl group properties and is polymerisable.

Question 21

What is the function of the acid pendant monomer/resin in PAMCs

Answer 21

Provides carboxyl groups and is hydrophilic

Question 22

What is the function of the cross linking resins in PAMCs

Answer 22

Provides harder and tougher matrix

Question 23

What is the function of fluorosilicate glass in PAMCs

Answer 23

Filler and source of fluoride, undergoes acid base reaction

Question 24

What is the function of CPQ/amines in PAMCs

Answer 24

Photoinitiator system

Question 25

What is the function of stabilisers in PAMCs

Answer 25

Extends the shelf life

Question 26

What does the base resin of GICs form

Answer 26

polymerises and forms matrix of cement

Question 27

How does the principle setting reaction of PAMCs happen

Answer 27

By photo initiation of the methacrylate groups

Question 28

What allows the acid base reaction to occur after curing of PAMCs

Answer 28

Water uptake into the mouth

Question 29

What allows fluoride release in PAMCs

Answer 29

the acid base reaction that occurs after curing

Question 30

Describe the properties of PAMC

Answer 30

- Good handling, easy to adapt to cavity walls and do not slump - requires dentin bonding agent and incremental placement - Shrinkage similar to composite - Level of water uptake smiler to composite but rate of uptake is faster - Possible compensation for shrinkage, shrinks in volume then can expand back to near normal - Inferior mechanical properties compared to composites

Question 31

What are the uses of PAMCs

Answer 31

- used in low stress situations - Proximal and abrasion cavities - Permanent restorations in primary teeth - Long term temporary in permanent teeth - More recently as a luting cement

Question 32

Describe the structural difference in Giomers compared to conventional GICs

Answer 32

- Composite resin plus pre-reacted glass ionomer particles as filler - Has fluoride release and recharge of GICs with the superior properties of a composite

Question 33

What are boomers used for

Answer 33

Restoratives Luting cement Fissure sealants

Question 34

Name a couple disadvantages of Compomers for me b xx

Answer 34

- Low level fluoride release post-placement | - requires bonding agent and placed incrementally