Quiz 1: Composite Materials

Question 1

Composite Materials:

What are the four major components of resin composite restorative materials?

Answer 1

1) Inorganic filler particles
2) Initiator-accelerator system
3) Organic polymer matrix
4) Coupling agent

Question 2

Composite Materials:

List the three types of Organic polymer matrix used in composite materials.

Answer 2

Oligomers:

1) Bis-GMA
2) U-DMA
3) TEG_DMA

Question 3

Composite Materials:

What is the role of a coupling agent used in composite materials?

• what does it link?
• During setting, what bond must form?

Answer 3

Links filler compartment to filling material

• A bond must form between the inorganic filler and the organic oligomer during setting.
• During the setting of the oligomer the double bonds of the silane react with the oligomer to form a link from the filler through the coupling agent to the oligomer to the polymer matrix.

Question 4

Composite Materials:

What’s the purpose behind using a microfilled in fillers?

• Microfilled composites have E value of what???… to make it more highly filled Fine particle composites.
• • What happens when microfilled composites have a higher volume% of polymer?
• • What happens when microfilled composites have more polymer present?

Answer 4

• Non-Stress-bearing esthetic restorations
• Silica with high surface area added to oligomer
• Microfilled composites have E value of only ¼ to ½ that of more highly filled Fine particle composites.
• Microfilled composite has a higher volume % of polymer = more shrinkage 2 – 4%
• Microfilled has more polymer present = more expansion.

Question 5

Composite Materials:

What’s the purpose behind using a microhybrid filler as part of the composite materials?

• what kind of restorations
• what kind of particles
• has less of what as opposed to microfillers
• more or less shrinkage?

Answer 5

• Anterior and posterior restorations
• Mostly fine particles
• Microhybrid composite has less polymer matrix and may be stiffer but has less shrinkage.

Question 6

Composite materials:

What makes a polymer matrix “bad” in doing a composite

Answer 6

Increase in shrinkage of the polymer matrix ( Polymerization Shrinkage)

• • This leads to micro gaps.
• • A direct function of the volume fraction of polymer in the composite.

Question 7

Composite materials:

An increase in filler makes the teeth what? (Stronger or weaker)

Answer 7

Stronger

Question 8

Composite Materials:

What is a camphorquinone?

• • What does it absorb?
• • What’s the light range in which it can absorb and which range/value specifically?

Answer 8

Most common photoinhibitor

• Absorbs blue light
• 400-500 nm range (470 specifically)

Question 9

Composite Materials:

Bonding tends to fail at what interface?
aka….. what is considered “bond failure”…List four

Answer 9

• • Allows influx of oral fluids
    
    • • Marginal staining
    • • Secondary caries
• • Post Operative sensitivity

Question 10

Composite Materials:

What makes up the air inhibited layer and where is it found?

Answer 10

– Unreacted double carbon bonds
(Unreacted double bonds may be as high as 75% at the air inhibited surface layer.)
– Free Radicals
– Located on the surface of the composite

Question 11

Composite Materials:

Wear:

• • If you have a HIGHER filler volume, what will happen to the wear?
• • If you have a LOWER filler size, what will happen to the wear?

Answer 11

• • Higher filler volume = decreased wear

- - Lower filler size = decreased wear