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Flashcards in Introductory Deck (31)
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1

What does the structure of Dental materials influence?

Properties

2

What are dental composites used for?

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

3

What is the definition of a composite?

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

4

What does a dental resin composite consist of?

-resin
-filler
-coupling agent

5

What does a fibre reinforced material consist of?

-fibres of high strength and modulus
-embedded/bonded to a matrix

6

What are dental reinforced materials used for?

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

7

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

Statement of manufacture offered to all patients receiving dental appliance

8

What does the legal certificate include?

-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

9

What happens if the certificate is not offered?

MHRA enforce directive and failure to offer is a criminal offence

10

What makes the oral environment hostile?

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

11

what does the periodontal ligament act as in the mouth?

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

12

What materials are used by the dental team?

-gypsum materials
-waxes
-alloys
-polymers
-ceramics

13

Describe tensile laboratory test.

Force applied to elongate rod

14

Describe compressible laboratory test.

-opposite of tensile
-not recommended for brittle materials

15

When is diametral tensile strength used?

When materials are too brittle for conventional tensile techniques

16

Describe flexural.

-3 points
-splits equally in half

17

How do you calculate strain?

change in length/original length

18

how do you calculate stress?

F(N) / A(mm2)

19

What are the units of strain?

no units

20

what is modolus?

Measure of stiffness of a material

21

Describe the linear part strain / stress graph

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

22

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

The small shaded triangle

23

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

whole graph shaded in

24

Describe surface hardness indentor

Dimensions are measured and expressed as a number,:
-high numbers are low hardness

25

what are the two types of shear bond force?

Adhesive- two areas cleanly separate
cohesive - if the strength of bond is bigger than the material only some of the material separates

26

What is used to measure surface roughness?

profilometer

27

What is thermal diffusity?

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

28

what is rheological properties?

The study of materials flow properties
-rate of viscosity and how it varies with time and rate of shear

29

What are the 3 types of rheological properties?

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

30

What is corrosion?

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