Plastic restorations - resin modified glass Ionomer cements

Question 1

What type of reaction is the polymerisation component?

Answer 1

light activated free-radical methacrylate reaction

Question 2

What is the maximum depth of the cement which can be light cured (polymerisation)?

Answer 2

0.5mm

Question 3

Why is the max depth of light curing for the polymerisation reaction 0.5mm?

Answer 3

limited light transmission through these material

Question 4

What is a tri-cured glass ionomer resin?

Answer 4

material can be light cured and chemically cured

a second chemical initiator system has been incorporated into some RMGIC products to compensate for the limited light-cure polymerisation reaction

to set the resin

Question 5

What are the 2 types of reactions in order to set the resin part?

Answer 5

polymerisation reaction - free radical methacrylate reaction effected by light activation
- light

+ redox reaction
- chemical

Question 6

How any stages are in the dual-cured RMGIC reaction?

Answer 6

4

Question 7

What are the 4 clinical stages of the dual-cured RMGIC reaction?

Answer 7

1. commences when powder and liquid mixed together
2. light activation of polymerisation reaction
3. light activation stopped
4. restoration complete

Question 8

What are the 4 sages of the dual-cured RMGIC setting reaction?

Answer 8

Question 9

What are the stages of the tri-cured RMGIC setting reaction?

Answer 9

Question 10

Do the acid-base and polymerisation setting reactions need to be initiated at the same time?

Answer 10

yes

Question 11

Why do the acid-base and polymerisation setting reactions need to be initiated at the same time?

Answer 11

as the material wont fully set at the same time

Question 12

Why is does the acid-base and polymerisation reactions rarely start at the same time?

Answer 12

as the addition of HEMA retards the setting rate of the acid-base reaction

Question 13

Why does shrinkage occur?

Answer 13

polymerisation phase

Question 14

What kind of setting reaction occurs when HEMA polymerises?

Answer 14

exothermic

Question 15

What are the 2 mechanisms for bonding to the tooth?

Answer 15

calcium chelation

subsidiary collagen bonding

Question 16

What are factors limiting the success of the adhesive bond?

Answer 16

Question 17

What can cause excessive expansion?

Answer 17

affinity for polyHEMA for water can cause excess expansion if not mixed correctly (i.e too much monomer)

Question 18

What happens as the polyEMA absorbs water?

Answer 18

mechanical properties begin to fall

Question 19

What is the fluoride release like?

Answer 19

sustained release

Question 20

When is the most fluoride released form the cement?

Answer 20

first 10-15 days

Question 21

What allows fluoride release long-term?

Answer 21

slow setting of glass ionomer phase of the cement

polyHEMA matrix provides n easier pathway for the ionic species to migrate through the cement

HEMA is hydrophilic

Question 22

What is occurring as fluoride is released?

Answer 22

the restoration is degrading

Question 23

is R,GIC prone to staining?

Answer 23

yes, intrinsic staining

Question 24

When should a tri-cure system be used?

Answer 24

where the material cannot be fully light cured

Question 25

What can occur if the material is not fully cured?

Answer 25

unconverted monomer can easily leach out from incompletely cured RMGIC Adverse reactions reported with HEMA risk of damage to pulpal tissue if in contact

Question 26

What are the advantages of RMGIC?

Answer 26

Fluoride ion release early strength adhesion - molecular bonding long working time limited moisture sensitivity low solubility or erosion of cement margins simple to use command set can be finished immediately after light curing (resin part might be cured but the acid -base reaction will be going on for some time) seals dentinal tubules

Question 27

What can be released as part of the setting reaction?

Answer 27

benzoyl iodides and benzoyl bromides

Question 28

What are the benefits/disadvantages of releasing benzoyl iodides and benzoyl bromides during the setting reaction?

Answer 28

they are cytotoxic and can potentially mop up ay residual cavity bacteria

Question 29

What are the disadvantages of RMGIC?

Answer 29

EXOTEERMIC REACTION ON CURNG SHRINKAGE ON CURING INCOMPLETE CURE PROCEDES WEAK MATERIAL MONOMER LEACH SWELLIG DUE TO MOISTURE UPTAKE powder is moisture sensitive (storage problem) releasing benzoyl iodides and benzoyl bromid

Question 30

Why is there shrinkage on curing?

Answer 30

due to the polymer in it (resin)

Question 31

Why is phase separation a disadvantage?

Answer 31

lead to expansion and potentially fracture of the teeth

Question 32

where is the material weaker?

Answer 32

where redox setting of the resin phase is used

Question 33

When would you use the RMGIC?

Answer 33

Small-sized class I cavities class III and V cavities non-carious tooth surface loss lesions core build ups Can be used as a lining material and composite on top deciduous teeth blocking undercuts bonding dental amalgam

Question 34

How much tissue do you need remaining to use RMGIC?

Answer 34

>50%

Question 35

Why ca you use RMGI on deciduous teeth?

Answer 35

Question 36

How are RMGICs predominantly used?

Answer 36

lining material

Question 37

What does increasing the powder in the RMGIC do?

Answer 37

increase strength of the material and decrease its retention to tooth tissue and vice versa

Question 38

What 3 forms can the RMGIC come in?

Answer 38

powder/liquid encapsulated (best) paste/paste systems

Question 39

What does the paste/paste system claim to enhance?

Answer 39

the polishability and wear resistance by utilising nanotechnology

Question 40

Why can the paste/paste presentations lead to non-uniform mix?

Answer 40

may become separated during storage

Question 41

Do some RMGIC requirre a primer?

Answer 41

yes

Question 42

What is the role of a primer?

Answer 42

usually infiltrate the dentine and make alternative adhesive restorations less successful modify smear layer, wet tooth surface and facilitate adhesion of the RMGIC