Luting Agents

Question 1

What is the compressive and tensile strength of dentine?

Answer 1

CS - 275MPa

TS - 50MPa

Question 2

Name two examples of dental cements.

Answer 2

Zinc phosphate

Zinc polycarboxylate

Question 3

What are the two types of glass ionomer cement?

Answer 3

Conventional

Resin modified

Question 4

What are the problems of using zinc phosphate as a Luting cement?

Answer 4

Low initial pH (2)
Exothermic setting reaction
Not adhesive to tooth or restoration
Not cariostatic
Final set takes 24hrs
Brittle
Opaque

Question 5

What are the advantages of zinc polycarboxylate cement?

Answer 5

Bonds to tooth
Less Exothermic setting reaction
Cheap
PH low to begin with but returns to neutral v quickly

Question 6

What are the disadvantages of zinc polycarboxylate cement?

Answer 6

Difficult to mix
Difficult to manipulate
Soluble in oral environment at lower pH
Opaque
Lower modulus & compressive strength than zinc phosphate

Question 7

What properties are improved in RMGIC compared to GIC?

Answer 7

Shorter setting time
Longer working time
Higher compressive & tensile strength
Higher bond strength to tooth
Decreased solubility

Question 8

What are the potential problems with RMGIC?

Answer 8

HEMA is cytotoxic
HEMA expands in a wet environment
No bond to indirect restoration

Question 9

How is porcelain bonded to by Luting agents?

Answer 9

Porcelain treated with hydroforic acid in the lab to etch its surface.
A surface wetting agent is also required (silane coupling agent).
Silane coupling agent forms a strong covalent bond with oxide groups on the porcelain surface and the other silane molecule has a C=C bond which reacts with the composite resin Luting agent.

Question 10

When should dual-curing Luting cements be avoided?

Answer 10

Small/thin veneers as they are likely to stain in the long term

Question 11

How can metal restorations be treated to bond to composite resins?

Answer 11

Etching or sandblasting

Question 12

What is panavia?

Answer 12

A self-adhesive composite resin

Question 13

What are the two main types of temporary cements?

Answer 13

With eugenol

Without eugenol

Question 14

How do you decide what Luting cement to use?

Answer 14

If the material would be damaged by you squeezing it with your fingers then it needs to be bonded to the tooth e.g. Porcelain inlays, belle glass inlays
If you could stand on it and not break it then it doesn’t need to be bonded to tooth e.g. MCC, gold, zirconium, posts. A cement such as GIC is a good choice.

Question 15

Name four types of Luting agents.

Answer 15

Dental cements
Composite resins
Self-adhesive composite resins
Surface modifying chemical