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Flashcards in intro to dental materials Deck (27):
1

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

ICI
1981
Dart and Nemcek

2

What are dental composites used for?

restorative material
special tray construction

3

What does a fibre reinforced composite consist of?

fibres of high strength and modulus
embedded/bonded to matrix

4

What have dental fibre reinforced materials been used for ?

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

5

What states the legal requirements of dental materials?

Medical Devices Directive

6

What makes the mouth a hostile environment?

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

7

What does tensile mean?

force applied to elongate a rod

8

What is strain?

change in length/original length

9

What units is strain measured in?

no units

10

What does compressive mean?

force applied to compress a material

11

What types of materials can not be compressed?

brittle materials eg. composite

12

What is diametral tensile strength testing used for?

brittle materials where conventional tensile not suitable

13

What is flexural?

3 point

14

what does ductility mean?

potential for material to be drawn out into wire

15

What does a high number re. surface hardeness mean?

low hardness

16

What does a low number re. surface hardness mean?

high hardness

17

What does shear bond strength test test for?

adhesive and cohesive failure

18

What does impact strength test test for?

pendulum swing fractures
consumes energy

19

What tests for surface roughness?

profilometer

20

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

rougher material

21

Studies of rheological properties is the study of what?

how materials flow

22

What does viscosity vary with?

rate of sheer and time

23

what does dilatant mean?

viscosity increases with applied pressure

24

What does Newtonian mean?

Viscosity remains constant with applied pressure

25

what does pseudoplastic mean?

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

26

What do tests of corrosion define?

chemical reactivity of metals and alloys

27

how are biological properties tested?

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