Introduction To Dental Materials Flashcards Preview

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Flashcards in Introduction To Dental Materials Deck (48):
1

Who invented the visible light curing unit?

Dart and namcek 1981

2

What was the name of the first dental light curing unit?

ICI dental occlusin

3

What are dental composites used for?

Restorative filling material
Special tray construction

4

What does a dental resin composite consist of?

Resin
Filler
Coupling agent

5

What are fibre reinforced materials?

Light weight
Strong
Used for bulletin proof vests
Used as a type of composite

6

What are fibre reinforced materials made up of?

Kevlar fibres
Fluoroelastomer rubber

7

What makes the mouth a hostile environment?

Loading of up to 6kg
On/off cyclical forces- fatigue
Chemicals
Temperature fluctuation

8

What vertical displacement forces are permitted in the periodontal ligament?

25-100 um

9

What are the Bucco lingual displacement permitted?

56-108um

10

What size of force intrudes the tooth?

1N

11

What size of force flexes bone and causes pain?

15N

12

What ph fluctuations occur within the mouth?

2-12

13

What materials are used by the dental team?

Gypsum materials (plaster)
Waxes
Alloys
Polymers
Ceramics

14

What does tensile mean?

Capable of being bent, shaped or drawn out

15

What is strain?

Change in length/ original length

16

What unit is strain measured in ?

Strain has no units

17

What is stress expressed as?

MPa
A is mm2
F is Newtons

18

What does compressive mean?

The ability to compress- not recommended for brittle materials

19

What is diamentral tensile strength?

Useful for brittle materials where conventional tensile not applicable

20

How many points to diamentral tensile strength?

2

21

How is diamentral tensile strength measured?

2F / pieDL ( diameter, length)

22

What does flexural mean?

The highest stress experienced at moment of rupture.

23

How is flexural strength measured?

3FL/ 2bd2

24

What is ductility?

The potential for material to be drawn out into a wire

25

What does modulus give?

A measure of stiffness

26

What is a measure of resilience?

The energy absorbed by material undergoing plastic deformstion up to elastic limit

27

What is a measure of toughness?

Total amount of energy a material can absorbs to point of fracture

28

What makes a material tough?

High measure of toughness

29

What makes a material brittle?

Low measure of toughness

30

How is fatigue measured?

Application of cyclic loading for a defined number of cycles.

31

What measures surface hardness?

An indentor

32

What does a large number on the indentor indicate?

Low hardness

33

What does a small number on the indentor indicate?

High hardness

34

What is sheer bond strength?

The amount of force required to break the bond between material and tooth surface
Adhesive failure
Cohesive failure

35

What is impact strength?

Quoted in units of energy
Measure of the force required to fracture

36

What is surface roughness measured by?

Profilemeter

37

What does the Profilemeter do?

Assesses surface characteristics

38

What does a high reading on the Profilemeter mean?

High reading the rougher the material

39

What is thermal conductivity?

Rate of heat transfer through a material (K)

40

What is specific heat?

Energy required to heat up a material (Cp

41

What is thermal diffusity?

The rate that temperature will rise in a material when heat is applied to its surface ( D )

42

How is thermal diffusity measured?

Thermal conductivity / specific heat

43

What are rheological properties?

Study of viscosity

44

What does dilatant mean re. Rheological properties?

Viscosity increases with applied pressure

45

Wha t does Newtonian mean re. Rheological properties?

Viscosity remains constant with applied pressure

46

What does pseudoplastic mean re. Rheological properties?m

Viscosity decreases with applied pressure and unless set increases when pressure decreases

47

What does corrosion mean?

Defines the chemical reactivity of metals and alloys

48

What is camphorquinone?

Widely used visible light photo initiator