intro to dental materials Flashcards

1
Q

What was the first light curing unit?
When?
who?

A

ICI
1981
Dart and Nemcek

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2
Q

What are dental composites used for?

A

restorative material

special tray construction

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3
Q

What does a fibre reinforced composite consist of?

A

fibres of high strength and modulus

embedded/bonded to matrix

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4
Q

What have dental fibre reinforced materials been used for ?

A

inlays and onlays
crowns and bridges
posts to reinforce and restore rct teeth.

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5
Q

What states the legal requirements of dental materials?

A

Medical Devices Directive

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6
Q

What makes the mouth a hostile environment?

A

loading of up to 6kg
on/off cyclical forces- fatigue
chemicals
temperature fluctuations- -14- 60 degrees

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7
Q

What does tensile mean?

A

force applied to elongate a rod

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8
Q

What is strain?

A

change in length/original length

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9
Q

What units is strain measured in?

A

no units

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10
Q

What does compressive mean?

A

force applied to compress a material

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11
Q

What types of materials can not be compressed?

A

brittle materials eg. composite

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12
Q

What is diametral tensile strength testing used for?

A

brittle materials where conventional tensile not suitable

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13
Q

What is flexural?

A

3 point

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14
Q

what does ductility mean?

A

potential for material to be drawn out into wire

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15
Q

What does a high number re. surface hardeness mean?

A

low hardness

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16
Q

What does a low number re. surface hardness mean?

A

high hardness

17
Q

What does shear bond strength test test for?

A

adhesive and cohesive failure

18
Q

What does impact strength test test for?

A

pendulum swing fractures

consumes energy

19
Q

What tests for surface roughness?

A

profilometer

20
Q

What does a high reading (R) on profilometer mean?

A

rougher material

21
Q

Studies of rheological properties is the study of what?

A

how materials flow

22
Q

What does viscosity vary with?

A

rate of sheer and time

23
Q

what does dilatant mean?

A

viscosity increases with applied pressure

24
Q

What does Newtonian mean?

A

Viscosity remains constant with applied pressure

25
Q

what does pseudoplastic mean?

A

viscosity decreases with applied pressure and unless set increased when pressure decreases

26
Q

What do tests of corrosion define?

A

chemical reactivity of metals and alloys

27
Q

how are biological properties tested?

A

laboratory screening
limited lab in vivo usage
human randomised controlled clinical trial