intro

Question 1

what indicates a material is safe?

Answer 1

a CE mark

Question 2

what are the 5 restorative materials available?

Answer 2

amalgam
composite
glass ionomer cements
compomers
procelain

Question 3

what 4 impression materials are available?

Answer 3

impression compound
impression paste
hydrocolloids
-alginate
elastomers
-polysulphides
-polyethers
-silicones

Question 4

what is the purpose of impression materials?

Answer 4

record position, shape and dimention of dentition

Question 5

what metals/alloys are available?

Answer 5

amalgam
cobalt chromium
titanium
gold
stainless steel

Question 6

describe porcelain?

Answer 6

similar appearance to enamel so suits anteriors
ceramic veneers common
-material bounded to tooth aesthetically satisfying, hard, rigid, not always most appropriate

Question 7

describe composite resin

Answer 7

initially
flows out of cartridge
low to high viscosities 
finally
sets within margins
hardens

Question 8

describe amalgam?

Answer 8

not aesthetic

good for substantial restorations

Question 9

describe impression materials

Answer 9

initially
flows into tray
low viscosity
finally
undergoes setting reaction
firm, stable

Question 10

what is gypsum?

Answer 10

dental stone

allows studying and making appliances

Question 11

what is ppma?

Answer 11

dentures acrylic resin
high quality
polymethylmethacrylate

Question 12

when is stainless steel used?

Answer 12

denture base
strong enough to withstand biting forces
orthodontic appliance
can be adjusted easily for ideal fit

Question 13

when is cobalt chromium used?

Answer 13

partial denture

able to withstand engagement and disengagement over long period

Question 14

What consequences can happen when a force is applied to a material?

Answer 14

Stretch/compress
-depends how force applied
Deform
-temporary/permanent
Fracture
-failure

Question 15

What are the 3 types of force?

Answer 15

Compressive
Tensile
Shear
-parallel to surface object is attached

Question 16

What is the formula for stress?

Answer 16

Force/unit area

Question 17

What is the formula for strain?

Answer 17

Force/unit area

Question 18

What is the formula for rigidity? (elastic modulus)

Answer 18

Stress/strain

Question 19

What are the 8 possible mechanical properties?

Answer 19

Hard, soft, strong, weak, rigid, flexible, brittle, ductile

Question 20

What are the mechanical properties of enamel?

Answer 20

Brittle, hard, strong, rigid

Question 21

What force does biting apply to teeth?

Answer 21

Compressive

-to upper tooth

Question 22

What forces are experienced when grinding/chewing?

Answer 22

Tooth slides along surface of the other

Frictional forces

Question 23

What is the consequence of biting (compressive forces)

Answer 23

fracture

Question 24

What is the consequence of grinding/chewing?

Answer 24

abrasion

Question 25

Why do restorative materials have to be adhered to enamel?

Answer 25

If not they will be removed by masticatory force

Question 26

What restorative material required an undercut?

Answer 26

amalgam

Question 27

How does amalgam achieve retention?

Answer 27

undercut-mechanical

Question 28

How does composite resin achieve retention?

Answer 28

adhesive

Question 29

What are the requirements of a filling material?

Answer 29

Must be pliable, to fit shape of interest, must set to form hard, strong material

Question 30

What is the failure mechanism of fracture?

Answer 30

Large force causes catastrophic destruction of materials structure

Question 31

What is the failure mechanism of hardness?

Answer 31

Ability of surface to resist indentation

Question 32

What is the failure mechanism of abrasion?

Answer 32

Material surface removal due to grinding - tooth grinds/slides along opposing tooth surface - loss of material surface layers, roughened surface

Question 33

What is the failure mechanism of abrasion resistance?

Answer 33

Ability to withstand surface layers being removed, so compromising surface integrity

Question 34

What is the failure mechanism of fatigue?

Answer 34

Repetitive small stresses cause material fracture

Question 35

What is the failure mechanism of creep?

Answer 35

Gradual dimensional change due to repetitive small forces

Question 36

What is the failure mechanism of deformation?

Answer 36

Applied stress causes permanent change in materials dimensions

Question 37

What is the failure mechanism of de-bond?

Answer 37

Applied forces sufficient to break material-tooth bond

Question 38

What is the failure mechanism of impact?

Answer 38

Large, sudden force causes fracture

Question 39

Why is a rough surface bad?

Answer 39

can act as plaque trap

Question 40

where is de-bonding commonly used?

Answer 40

in removal of orthodontic appliance | -shear force used to separate bracket/bonding material from tooth surface

Question 41

what chemical properties should be considered?

Answer 41

setting mechanism setting time corrosive potential

Question 42

what physical properties should be considered?

Answer 42

``` viscosity thermal conductivity thermal expansion density radiodensity ```