Introduction To Dental Materials

Question 1

Who invented the visible light curing unit?

Answer 1

Dart and namcek 1981

Question 2

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

Answer 2

ICI dental occlusin

Question 3

What are dental composites used for?

Answer 3

Restorative filling material

Special tray construction

Question 4

What does a dental resin composite consist of?

Answer 4

Resin
Filler
Coupling agent

Question 5

What are fibre reinforced materials?

Answer 5

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

Question 6

What are fibre reinforced materials made up of?

Answer 6

Kevlar fibres

Fluoroelastomer rubber

Question 7

What makes the mouth a hostile environment?

Answer 7

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

Question 8

What vertical displacement forces are permitted in the periodontal ligament?

Answer 8

25-100 um

Question 9

What are the Bucco lingual displacement permitted?

Answer 9

56-108um

Question 10

What size of force intrudes the tooth?

Answer 10

1N

Question 11

What size of force flexes bone and causes pain?

Answer 11

15N

Question 12

What ph fluctuations occur within the mouth?

Answer 12

2-12

Question 13

What materials are used by the dental team?

Answer 13

Gypsum materials (plaster)
Waxes
Alloys
Polymers
Ceramics

Question 14

What does tensile mean?

Answer 14

Capable of being bent, shaped or drawn out

Question 15

What is strain?

Answer 15

Change in length/ original length

Question 16

What unit is strain measured in ?

Answer 16

Strain has no units

Question 17

What is stress expressed as?

Answer 17

MPa
A is mm2
F is Newtons

Question 18

What does compressive mean?

Answer 18

The ability to compress- not recommended for brittle materials

Question 19

What is diamentral tensile strength?

Answer 19

Useful for brittle materials where conventional tensile not applicable

Question 20

How many points to diamentral tensile strength?

Answer 20

2

Question 21

How is diamentral tensile strength measured?

Answer 21

2F / pieDL ( diameter, length)

Question 22

What does flexural mean?

Answer 22

The highest stress experienced at moment of rupture.

Question 23

How is flexural strength measured?

Answer 23

3FL/ 2bd2

Question 24

What is ductility?

Answer 24

The potential for material to be drawn out into a wire

Question 25

What does modulus give?

Answer 25

A measure of stiffness

Question 26

What is a measure of resilience?

Answer 26

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

Question 27

What is a measure of toughness?

Answer 27

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

Question 28

What makes a material tough?

Answer 28

High measure of toughness

Question 29

What makes a material brittle?

Answer 29

Low measure of toughness

Question 30

How is fatigue measured?

Answer 30

Application of cyclic loading for a defined number of cycles.

Question 31

What measures surface hardness?

Answer 31

An indentor

Question 32

What does a large number on the indentor indicate?

Answer 32

Low hardness

Question 33

What does a small number on the indentor indicate?

Answer 33

High hardness

Question 34

What is sheer bond strength?

Answer 34

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

Question 35

What is impact strength?

Answer 35

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

Question 36

What is surface roughness measured by?

Answer 36

Profilemeter

Question 37

What does the Profilemeter do?

Answer 37

Assesses surface characteristics

Question 38

What does a high reading on the Profilemeter mean?

Answer 38

High reading the rougher the material

Question 39

What is thermal conductivity?

Answer 39

Rate of heat transfer through a material (K)

Question 40

What is specific heat?

Answer 40

Energy required to heat up a material (Cp

Question 41

What is thermal diffusity?

Answer 41

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

Question 42

How is thermal diffusity measured?

Answer 42

Thermal conductivity / specific heat

Question 43

What are rheological properties?

Answer 43

Study of viscosity

Question 44

What does dilatant mean re. Rheological properties?

Answer 44

Viscosity increases with applied pressure

Question 45

Wha t does Newtonian mean re. Rheological properties?

Answer 45

Viscosity remains constant with applied pressure

Question 46

What does pseudoplastic mean re. Rheological properties?m

Answer 46

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

Question 47

What does corrosion mean?

Answer 47

Defines the chemical reactivity of metals and alloys

Question 48

What is camphorquinone?

Answer 48

Widely used visible light photo initiator