Provisional Restorative Materials (Johnston)

Question 0

What are three advantages of resin based restorative materials?

Answer 0

1. Relative ease of formation
2. Translucency
3. Thermally and electrically insulating

Question 1

What are four properties of provisional restorative materials?

Answer 1

1. Ease of formation
2. Promotes oral health
3. Esthetic appearance
4. Stable and durable

Question 2

What are five disadvantages of resin based restorative materials?

Answer 2

1. Exoteric reaction
2. Polymerization shrinkage
3. Variable polymerization efficiency
4. High coefficient of thermal expansion on heating
5. Low toughness

Question 3

What are the two categories of polymers?

Answer 3

Thermoplastic: no cross linking, reversibly controlled by temp
Thermoset: involves irreversible cross linking

Question 4

What are two mechanisms of polymerization or setting?

Answer 4

1. Addition polymerization releases no by products

2. Condensation polymerization results in a by product

Question 5

What is the most exclusive polymeration method for current dental resins?

Answer 5

Free radical polymerizations

Question 6

What are physical phenomena during free radical polymerization?

Answer 6

1. Final properties increased
2. Material heats up
3. Volumetric contraction

Question 7

What are the four chemical stages of polymerization?

Answer 7

1. Activation of initiator
2. Activation of monomer
3. Polymer growth
4. Termination

Question 8

What are Some properties of activation of initiator?

Answer 8

Highly efficient
Is uniform
Large working time
Mixing of initiator and monomer
Needs hearing equipment

Question 9

What does excessive heat cause?

Answer 9

Porosity

Question 10

What are the three steps in the activation of initiator?

Answer 10

1. Heat activation
2. Chemical activation
3. Light activation

Question 11

What does cross linking do to a material?

Answer 11

Cross linking makes the material more durable and resists staining

Question 12

What happens chemically in the activation of monomer?

Answer 12

Free radical + monomer-> active monomer

Change of double bond to two single bonds release heat

Question 13

Explain the growth of polymer step

Answer 13

• Active polymer spontaneously combines w more monomer
• Heat of reaction heats material
• Increases density
• cross linking between two growing polymers

Question 14

What are characteristics of the greater the size of a methacrylate monomer?

Answer 14

• less polymerization shrinkage
• less heat of reaction
• lower mechanical properties

Question 15

What occurs in the termination step?

Answer 15

• two active polymers can combine
• free radical transfer causes polymer to stop growing
• contaminants

Question 16

T or f: more filler the stronger the material

Answer 16

True

Question 17

T or f: most methacrylates are translucent

Answer 17

True