Resin Composites Flashcards

1
Q

What is a resin composite?

A

a combination of 2 chemically different materials with a distinct interface separating the components.

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2
Q

What are resin composited used for?

A

tooth coloured fillings

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3
Q

What is the earliest direct tooth coloured restorative material called?

A

Forerunner’s silicates

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4
Q

What is the setting reaction of forerunners silicates?

A

aluminosilicate glass + phosphoric acid = salt and water

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5
Q

Where are acrylics derived from?

A

products used to make dentures

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6
Q

What type of set do acrylics have?

A

chemical

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7
Q

In resin composite, what is the resin matrix usually based upon?

A

methyl methacrylate or dimethacrylate monomers

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8
Q

What are the 3 components of the resin matrix?

A
  • Methacrylate/ dimethacrylate monomer
  • Comonomers i.e., TEGMA
  • Inhibitors
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9
Q

What reaction occurs in retained acrylics in resin composites?

A

free radical polymerisation

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10
Q

What is polymerisation triggered by?

A

light curing

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11
Q

What do fillers have to be coupled with?

A

coupling agent

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12
Q

What are coupling agents used for?

A

improve the adherence of resin to filler surface

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13
Q

What is the purpose of fillers?

A

reduce shrinkage

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14
Q

What is the name of the coupling agent in resin composites?

A

vinylsilate

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15
Q

What is silane?

A

a filler

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16
Q

What happens to surface hardness as filler content increases?

A

surface hardness increased

17
Q

What happens to volume when filler is added?

A

decreases percentage volume by setting

18
Q

What happens to thermal expansion when filler is added?

A

thermal expansion decreases

19
Q

What is the visible blue light used to set resin composites called?

A

camphorquinone

20
Q

What do all resin composites contain?

A

resin
filler
coupling agent

21
Q

What are resin and filler useless without?

A

coupling agent

22
Q

What is the role of coupling agent?

A

transfers the stress generates under loading from the rigid and brittle filler to the more flexible and ductile polymer matrix

23
Q

What are the 4 types of resin composites based on filler particle size?

A
  • conventional
  • microfilled
  • hybrid
  • nanocomposites
24
Q

What must the properties of resin composite conform to?

25
What happens to viscosity on leaving the tube?
increases
26
What are the disadvantages of resin composite?
may stain as resin matrix can take up fluids e.g., wine
27
What influences the overall success of a restoration?
cavity shape
28
What is C factor?
number of bonded surfaces/ number of un-bonded surfaces
29
What does C factor relate to?
shrinkage
30
What type of setting occurs in resin composite?
exothermic
31
What can trapped air pockets in resin composite result in?
inhibition of polymerisation and softens the matrix
32
What are nanofillers?
fillers with particle sizes ranging from 1-1nm
33
What is the optimum absorption of camphorquinone?
460-480nm
34
What happens when composite cures?
contraction
35
What are the 3 mechanisms influences by chemical effects?
- abrasive - erosive - fatigue
36
What is the name of the coupling agent?
vinylsilane