Restorative Materials

Question 0

Is a composite resin a bonded or unbonded restoration? Explain the clinical significance.

Answer 0

Bonded

This increases the strength of the remaining tooth structure

Question 1

Is a composite resin’s thermal conductivity high or low? Is this an advantage?

Answer 1

Low

Yes

Question 2

What is a composite resin’s linear coefficient for thermal expansion? Explain its clinical significance.

Answer 2

High
CR may expand or contract more that tooth when there is a change in temperature. If it shrinks too much, baka maalis siya?

Question 3

Composite resins are not recommended for lesions extending to the root portion. What is a good alternative to this?

Answer 3

Glass ionomer cements

Question 4

Explain briefly the history of tooth-colored restorations.

Answer 4

X

Question 5

Differentiate direct from indirect composite resins.

Answer 5

X

Question 6

What is the composition of composite resin?

Answer 6

• Resin matrix (principal monomer and diluent monomer)
• Inorganic fillers
• Coupling agent
• Initiator-Activator System
• Polymerization Inhibitor
• Optical modifiers

Question 7

Describe high-molecular-weight monomers at room temperature

Answer 7

Extremely viscous

Question 8

How does a diluent monomer affect viscosity?

Answer 8

Reduces viscosity

Question 9

Give examples of principal monomers and diluent monomers.

Answer 9

Principal
- Bis-GMA (Bowen’s resin), UDMA, 4-META
Diluent
- TEGDMA (triethylene glycol dimethacrylate)

Question 10

Explain the function of inorganic filler.

Answer 10

Reduces polymerization shrinkage since there’s less resin
Less coefficient of thermal expansion
Shift from large to small particles to produce better surface finish

Question 11

There should be a balance of small and large fillers in composite resins. What are the advantages and disadvantages of each?

Answer 11

Small: good surface finish, poor mechanical properties
Large: poor surface finish, good mechanical properties

Question 12

What is the function of a coupling agent?

Answer 12

Provides stable adhesive bonding of the inorganic fillers to the organic matrix
Stress absorber at the filler-matrix interface

Question 13

Give an example of commonly used coupling agents.

Answer 13

Organosilanes (e.g. y-methacryloxypropylrrimethoxysilane

Question 14

What are the three types of initiator-activator systems?

Answer 14

Chemically activated
UV light activated
Visible light activated

Question 15

What is the initiator and activator of chemically-activated composite resins?

Answer 15

I: Benzoyl peroxide initiator
A: Tertiary amine activator

Question 16

What is the initiator and activator of UV light activated composite resins?

Answer 16

I: Benzoin methyl ether
A: UV light

Question 17

Which of the three initiator-activator systems is obsolete? Why?

Answer 17

UV light because it is cancerous

Question 18

What is the initiator and activator of visible light activated composite resin?

Answer 18

I: Camphorquinone
A: visible light (400-500 nm)