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Dental Materials > All > Flashcards

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1
Q

What is a dental composite made up of

A

Combination materials which individual components retain identify and possess diff properties

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2
Q

What does a dental resin composite consist of

A

Resin
Filler
Coupling agent

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3
Q

What does a fibre reinforced material consist of

A

Fibres in a high strength modulus

Bonded to a matrix

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4
Q

What doe the materials maintain in a fibre reinforced material

A

District boundaries between components

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5
Q

What are the properties of a fibre reinforced components

A

Have properties that cannot be achieved with any constituents alone

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6
Q

What are some uses of dental fibre reinforced materials

A

Crowns
Bridges
Posts

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7
Q

What is the legal requirement regarding the statement of manufacture

A

Should be offered to pt

Pt name and confirmation
Presenter details
Technicians details
Confirmation

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8
Q

What are some materials used by the dental team

A 
Polymers
Ceramics 
Gypsum 
Alloys 
Waxes
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9
Q

What are all the standard (organisations) a material must be tested by

A

Individuka organisations

British standard
International standards

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10
Q

What are some things to consider about the oral environment

A 
Hostile
Temp fluctuations 
Ph 
Forces 
Chemical
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11
Q

What are some mechanical properties taken into consideration for mateials

A 
Tensile 
Compressive 
Outputs
Flexural 
Diametral flexural 
Impact strength 
Surface hardness
Shear bond strength 
Fatigue
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12
Q

What si the tensile strength

A

Force applied to elongate

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13
Q

What si the equation for the tensile strength

A 
Q = F/A 
Strain = change in length
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14
Q

What is compressive test not good for

A

Brittle substances

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15
Q

What is hooks law

A

Stress + strain are linear and proportional relationship

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16
Q

If a force is removed whilst in the elastic region what will happen

A

Recoil

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17
Q

Think of the outputs graph what are the axis etc

A

X axis - linear elastic section and all the way along is the ductility

Y axis - stress

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18
Q

What si the elastic of the outputs also known as (measure of)

A

Measure of resilience

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19
Q

What si the ductili of the output a measure of

A

Toughness

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20
Q

What is the equation and the flexural strength

A

3 points
Support seperation
Q = 3FL/2bd^2

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21
Q

What sit he equation for the diametral tensile strength

A

Q = 2F/ (Pi)DL

Useful for brittle materials

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22
Q

What si the impact strength

A

How consumes energy
Pendulum swing
Units of energy

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23
Q

What si the surface hardness measured

A

Large numbers = low harness

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24
Q

What is the sheer bond strength

A

Cohesive and adhesive failure

Q = F/A

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25
Q

What’s it eh fatigue of a material,

A

Application of cyclic loading of a defined number of cycles until final

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26
Q

What are the types of non elastic impression materials

A

Impression plaster
Impression waxes
Impression compound
Zinc oxide or eugenol pastes

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27
Q

What does the non elastic impression materials unable to do

A

Inability to accurately record undercuts

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28
Q

What are the types of elastic impression materials

A

Synthetic elastomers

Hydrocolloids

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29
Q

What are the two types of hydrocolloids

A

Agar and alignate

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30
Q

What are some of the annotations of agar

A

Gel
Borax gives body
K2SO4 counteract the borax
Requires a water bath

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31
Q

What are the temperatures of the agar for the water bath

A

100 - gel to sol
65 - hold temp
45 - clinical use

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32
Q

How do u make alginate

A

Water and power

Irreversible

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33
Q

What are the properties of alginate

A

Elastic
Low visc - mucostatic
Rapid set
Working time

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34
Q

What does sodium Phosohate do for the setting properties of alginate

A

Removes supply of insoluble calcium for cross linking therefore extending working time

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35
Q

What are the alternatives to impressions

A

Cad cam

Intra oral scanner

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36
Q

What are flabby ridges

A

Appears supporting bone is present but it is not

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37
Q

What are the disads to agar

A 
Cross infection 
Cost 
Soecial equipment
Low tear 
Dimensional instability
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38
Q

What is agar clinical used for

A

Crowns and bridges

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39
Q

What si agar used for in the lab

A

Duplications

40
Q

What are the ads of agar

A

Takes up moisture

Reuse

41
Q

What si the composition of alginate

A

Na/K alignic acid
CaSo4.H2O
Na3PO4
Inert filler

42
Q

What does the Na/K aliginic acid do in alginate

A

Forms solution with water and becomes a gel with cross links

43
Q

What does gypsum (caso4.h2o) do in alginate

A

Source of calcium for cross linking

44
Q

What does Na3PO4 do in alginate

A

Used to contro the work time

45
Q

What does the inert filler do in alginate

A

Give body

46
Q

What are some physical properties of impression materials

A 
Thermal 
Rheological 
Viscosity 
Thermal expansion and contraction 
Surface roughness
47
Q

What si the thermal property

A

Energy required to heat up material

Q= mst

48
Q

What si thermal diffusity and the equation

A

D = k/ Cp x P

D - thermal diffusity
K - thermal conductivity
Cp - specific heat
P - material density

49
Q

What si the rheological property

A

Study of the flow of properties

50
Q

What si the viscosity property

A

Varies with rate of sheer and time

Dilatant
Newtonian
Pseudo plastic

51
Q

What’s it he thermal expansion and contraction property

A

Match as closely to the tooth surface as possible

52
Q

What si the surface roughness property

A

Assessment of surface characteristic by Profilometer higher value more rough

53
Q

What a re the three biological a tests

A

Lab - irritation, colonogenic, systemic toxicity
Animal testing
Randomised human testing

54
Q

What is an ideal material

A

Non toxic
Non irritant
Harmless
No carcinogenic

55
Q

What are the thre main requirements of a impression material

A

Surface detail reproduced
Dimensional accuracy and stability
Taste, non toxic, doesn’t interact …..

56
Q

What are the two requirements for good surface detail reproduction

A

Viscosity

Hydrophobicity

57
Q

How does viscosity vary

A

Changes with time

Low visc = more detail not contained
High visc = less detail on flabby ridges, displaces tissue

58
Q

What is hydrophobicity

A

Moist repels it

Affects performance

59
Q

What a re the kinds of things required for dimensional accuracy and stability

A

Type of tray

Flexibility and recovery

Storage before casting

60
Q

How can the type of tray affect stability

A

Must have bonding adhesive

Flexible tray distorts impression

61
Q

What is flexibility and recovery important for the impression

A

Removal of undercuts

Elastic

62
Q

Why is storage before casting important

A

No design all changes should takes place

63
Q

What are the 4 elastomeric impression materials

A

Silicone rubbers- addition
Silicone rubbers - condensation
Polyethers
Polysulphides

64
Q

What are he 2 pastes of addition silicone rubbers

A

Paste 1 - inert filler, liquid silicone, catalyst

Paste 2 - liquid silicone prepolymer methyl replaced by hydrogen

65
Q

What si the setting for the silicone rubbers addition

A

Platinum catalyst

No by products

66
Q

What are the different kinds of viscosities of addition silicone rubbers

A

Putty
Medium body
Light body
Hydrophobic

67
Q

What are the forms condemnation silicone rubbers comes in

A

2 pastes or liquid+paste

68
Q

What are the 2 pastes for condensation silicone rubbers

A

Inert filler

Silicone liquid

69
Q

What is the liquid + paste for condensation silicone rubbers

A

Alkyl silicate

Tin

70
Q

What are the important parts of setting for condensation silicone rubbers

A

Cross linking
Alkyl silicate is a lining agent
Tin is a catalyst

71
Q

What si the by product of condensation silicone rubber

A

Ca2H5O

72
Q

What are the properties of the condensation silicone rubbers

A

Quicker elastic recovery
Faster setting
Hydrophobic
Non toxic

73
Q

What are the 2 pastes of polyether

A

Paste 1 - base inert filler, terminals polymer

Paste 2 - catalyst

74
Q

What a is the setting of the polyether

A

Cationic ring addition

Viscosity increases increasing cross links

75
Q

What are the 2 pastes for polysulphides

A

Base - terminal pendant thiol

Catalyst - PbO2

76
Q

What sit he setting for polysulphides

A

Condensation - water by prod
Disulphide bonds
Cross links

77
Q

What are the properties of polysulphides

A

High tear resist
Dimensional stability
Bad smell taste
Easily read

78
Q

How do u make gypsum

A

Calcium sulphate dihydrate to calcium sulphate hemihydrate driving water

79
Q

What are the three forms of gypsum

A

Dental plaster
Dental stone
Densite

80
Q

How do u make dental plaster

A

Heat gypsum with 120

81
Q

How do u make dental stone

A

Steam pressure autoclave 120 gypsum

82
Q

How do h make densite

A

Boil gypsum in CaCl2

83
Q

How do u set gypsum

A

Add water

84
Q

What does mixing gypsum do

A

Weakens
Air bubbles
Loss detail

85
Q

How do u overcome mixing issued

A

Use vibrations instead

86
Q

Form dental plaster to stone what per operatives change

A

Porosity and particle size decrease

87
Q

What are the ISO standards for gypsum

A

1) impression plaster mucostatic
2) dental plaster
3) dental stone for die
4) dental stone high strength low expansion
5) dental stone high strength high expansion

88
Q

What are the colours of plaster, stone and die stone

A

Paster - White
Stone - yellow
Die stone - pink/blue

89
Q

What doe die materials have to be

A 
Be dimensionally stable 
Fluid when poured 
Good wetting 
Hard and resistant once set 
Compatible with other materials
90
Q

Ephod can the control the setting time

A

Manufacturer
Operator
Accelerators and retarders control expansion

91
Q

What are the steps of setting gypsum

A

1 - water saturated with hemihydrate
2 - convert to dihydrate
3 - dihydrate crystallises out initaties by expo to nuclei of crystallatikn

92
Q

What hallens when gypsum setts

A

Increase visc (initial a DB final set )
Exothermic
Expansion outward crystals

93
Q

What are the adabatages of gypsum

A

Inexpensive
Easy to use
Electroplate to increase strength

94
Q

What are the disads to gypsum

A

May interact with borax in alginate

Hypochlorite may interact if not rinsed properly

95
Q

What si a dental composite used for

A

Restorative material and impression trays

Dental Materials (1 decks)

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