Introductory

Question 1

What does the structure of Dental materials influence?

Answer 1

Properties

Question 2

What are dental composites used for?

Answer 2

Used as restorative filling materials and also available for special tray construction

Question 3

What is the definition of a composite?

Answer 3

A combination of materials in which the individual components retain their identity and which possess different properties to the components acting alone

Question 4

What does a dental resin composite consist of?

Answer 4

• resin
• filler
• coupling agent

Question 5

What does a fibre reinforced material consist of?

Answer 5

• fibres of high strength and modulus

- embedded/bonded to a matrix

Question 6

What are dental reinforced materials used for?

Answer 6

• construction and reinforcement of denture bases
• inlays and onlays
• crowns and bridges
• posts to reinforce and restore root canal treatment

Question 7

What are the Legal requirements relating to the prescription of laboratory made dental appliances?

Answer 7

Statement of manufacture offered to all patients receiving dental appliance

Question 8

What does the legal certificate include?

Answer 8

• patients name and confirmation made for them
• prescribers name and registered address
• technicians name and registered address
• Description of the appliance
• confirmation meets legal standards

Question 9

What happens if the certificate is not offered?

Answer 9

MHRA enforce directive and failure to offer is a criminal offence

Question 10

What makes the oral environment hostile?

Answer 10

• loading of 6Kg
• On/off cyclical forces- fatigue
• chemicals
• temperature fluctuations in microsecond

Question 11

what does the periodontal ligament act as in the mouth?

Answer 11

acts as a shock absorber and permits both vertical and bucco lingual displacement

Question 12

What materials are used by the dental team?

Answer 12

• gypsum materials
• waxes
• alloys
• polymers
• ceramics

Question 13

Describe tensile laboratory test.

Answer 13

Force applied to elongate rod

Question 14

Describe compressible laboratory test.

Answer 14

• opposite of tensile

- not recommended for brittle materials

Question 15

When is diametral tensile strength used?

Answer 15

When materials are too brittle for conventional tensile techniques

Question 16

Describe flexural.

Answer 16

• 3 points

- splits equally in half

Question 17

How do you calculate strain?

Answer 17

change in length/original length

Question 18

how do you calculate stress?

Answer 18

F(N) / A(mm2)

Question 19

What are the units of strain?

Answer 19

no units

Question 20

what is modolus?

Answer 20

Measure of stiffness of a material

Question 21

Describe the linear part strain / stress graph

Answer 21

-the linear region is when stress and strain are equal and this can calculate modulus

Question 22

how can you tell the resilience on the stress/ strain graph?

Answer 22

The small shaded triangle

Question 23

how can you tell the toughness on the stress/strain graph ?

Answer 23

whole graph shaded in

Question 24

Describe surface hardness indentor

Answer 24

Dimensions are measured and expressed as a number,:

-high numbers are low hardness

Question 25

what are the two types of shear bond force?

Answer 25

Adhesive- two areas cleanly separate

cohesive - if the strength of bond is bigger than the material only some of the material separates

Question 26

What is used to measure surface roughness?

Answer 26

profilometer

Question 27

What is thermal diffusity?

Answer 27

The rate at which the temperature will rise in a material when heat is applied to its surface (high rate of diffusity preferred)

Question 28

what is rheological properties?

Answer 28

The study of materials flow properties

-rate of viscosity and how it varies with time and rate of shear

Question 29

What are the 3 types of rheological properties?

Answer 29

Dilatant- viscosity increases with applied pressure
Newtonian- viscosity stays the same with applied pressure
Pseudoplastic - viscosity decreases with applied pressure

Question 30

What is corrosion?

Answer 30

Defines the chemical reactivity of metals and alloys (should display good corrosion resistance)

Question 31

What 3 levels are biological properties tested at?

Answer 31

• Laboratory screening
• limited laboratory in vivo usage testing
• human randomised controlled clinical trial