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Dent Mat 1 > Elastomers > Flashcards

Elastomers Flashcards

1
Q

Elastomers are for what kinds of work

A

Crown and bridge work

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2
Q

Used when high degree of accuracy is needed

A

Elastomers

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3
Q

Rubber polymers, soft and rubber-like, easily stretched and rapidly recover

A

Elastomers

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4
Q

Elastomers are produced by

A

Vulcanization/ curing

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5
Q

Cross linking process that involves sulfur mercaptan groups

A

Vulcanization/curing

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6
Q

More fillers added
Increase or decrease of consistency of paste?
Increase or decrease of fluidity?

A

Increase consistency of paste

Decrease fluidity

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7
Q

Three types of viscosities

A

Light-body materials
Medium-body materials
Heavy-body materials

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8
Q

Syringing around prepared teeth to register finest details

A

Light-body materials

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9
Q

Type of viscosity that is too fluid when held in tray

A

Light-body material

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10
Q

Intermediate viscosity.
Viscous enough to fill and remain in tray.
Can be syringed like light-body

A

Medium-body materials

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11
Q

Putty
Fill the tray
Provide support for less viscous

A

Heavy-body materials

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12
Q

Ultimately more flexible light-body materials

A

Heavy-body materials

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13
Q

2 advantages of elastomers over hydrocolloids

A

Good tear resistance

Dimensional stability

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14
Q

Disadvantage of elastomers

A

Hydrophobic in nature

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15
Q

Types of elastomers

A

Polysulfide
Condensation silicone
Addition silicon
Polyether

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16
Q

Oldest most economic elastomer

A

Polysulfide

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17
Q

Not the most accurate and stable

And is supplied in 2 tubes

A

Polysulfide

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18
Q

2 tubes of polysulfide

A

Base

Catalyst

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19
Q

Chemical group containing long-chain organic polymer with many SH groups

A

Mercaptan

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20
Q

Meaning of SH groups

A

Sulfhydril

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21
Q

Liquid polymer made by mixing with fillers (silica particles) plus oils that improve handling of paste

A

Base paste

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22
Q

Usually pigmented white, stains clothing

A

Base paste

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23
Q

Composition of Base paste of polysulfide

A

Polysulfide
Filler
Plasticizer

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24
Q

Composition of base paste that GIVES BODY

A

filler

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25
Q

Composition of base paste that controls viscosity

A

Plasticizer

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26
Q

Contains Lead Dioxide and additional sulfur that both enhance the chemical reaction for transforming Paste to elastic rubber

A

Catalyst paste

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27
Q

Lead Dioxide and additional sulfur enhance chemical reaction for transforming?

A

Paste to elastic rubber

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28
Q

Paste that provide odor of the polysulfide

A

Catalyst paste

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29
Q

T or F

Catalyst paste also stains cloth and skin

A

True

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30
Q

Composition of Catalyst Paste

A

Lead Dioxide
Sulfur
Inert oil

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31
Q

Composition of catalyst paste that causes polymerization and cross-linking

A

Lead Dioxide

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32
Q

Composition of catalyst paste that facilitates reaction

A

Sulfur

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33
Q

Composition of catalyst paste that forms a paste

A

Inert oil

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34
Q

T or F

Polysulfide is easy to use

A

False

Polysulfide is more difficult to use

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35
Q

T or F

Polysulfide has a slightly greater tear strength

A

True

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36
Q

T or F

Polysulfide has more objectionable characteristics

A

True

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37
Q

Polysulfide is useful for teeth with?

A

Deep undercuts

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38
Q

Polysulfide manipulation

A

Squeeze equal length with 1 INCH INTERVAL

Mix 5-10 seconds, circular motion, CATALYST TO BASE

mixing 45 SECONDS
Full working time 5-7 MINS

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39
Q

Advantages of polysulfide

A 
Dimensional stability 
Accuracy 
Different viscosities
Long working time
Long shelf life

DAD LL

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40
Q

Disadvantages of polysulfide

A

Lead-oxide has toxic effects
Lead oxide stains
Unpleasant rubbery smell
Only be used in special tray

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41
Q

Working time of polysulfide

A

5-7 mins

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42
Q

Polysulfide is non toxic because?

A

When lead dioxide is mixed with catalyst, it becomes non toxic

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43
Q

Permanent deformation during removal of polysulfide, how many percent?

A

2% - 3%

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44
Q

T or F

Polysulfide is compatible with die and cast materials

A

True

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45
Q

Shelf life of polysulfide is extended when placed in?

A

Refrigerator

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46
Q

T or F

Polysulfide has a WHITE BASE and COLORED CATALYST

A

True

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47
Q

Polysulfide can be used repeatedly

A

Dimensional stability

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48
Q

Flow after setting of polysulfide

A

Pouring stone

49
Q

Consistency of polysulfide

A

Viscosity depends on reinforcing agents available

50
Q

Polysulfide doesn’t tear easily

A

Flexibility

51
Q

T or F
Polysulfide is compatible with electroforming.
It is good in reproducing details.

A

Both statements are true

52
Q

Althought it is stable, this elastomer should be casted in 24hrs

A

Condensation Silicone

53
Q

Tor F

Both pastes of condensation silicon contain liquid silicone polymer.

A

True

54
Q

Liquid silicone is made from?

A

Polydimethylsiloxane

55
Q

Polydimethylsiloxane contain many?

A

OH (hydroxyl) groups

56
Q

Which contains ORTHOALKYLSILICATE in condensation silicon, base or catalyst paste?

A

Base paste

57
Q

It is an organic molecule that causes polymer chains to become cross linked

A

Orthoalkylsilicate

58
Q

Cross-linked polymer chains in condensation silicon results to?

A

Transforming paste to fairly rigid and dimensionally stable

59
Q

It is a paste of condensation silicone that contains TIN OCTATE CATALYST

A

Catalyst paste of condensation silicon

60
Q

T or F

Catalyst paste of condensation silicon also contains the same component as base paste

A

True

61
Q

Which is labeled as the liquid components in condensation silicon, base or catalyst?

A

Catalyst paste

62
Q

Advantages of condensation silicone

A

Accurate
Ease of use
Used On severe undercuts

63
Q

Disadvantages of condensation silicon

A

Hydrogen evolution

Cause irritation

64
Q

Reaction in condensation silicon

A

Dimethylsilohexane +ortho-ethyl silicate + tin octate ➡️silicone rubber + ethanol

65
Q

T or F

Condensation silicon has a short working time

A

True

CS has 6-8 mins working time

66
Q

What happens during the 1ST hour of condensation silicon

A

Most dimensional changes occur

67
Q

T or F

Condensation silicon is also non toxic

A

True

68
Q

T or F

Condensation silicone is compatible with model plaster and electropating

A

True

69
Q

What elastomer has poor wettability

A

Condensation silicon

70
Q

What elastomer has
LOW permanent deformation and
LOW flow and flexibility but has
HIGH tear strength

A

Condensation silicone

71
Q

Addition silicone is also known as?

A

Polyvinylsiloxanes

72
Q

Polyvinylsiloxanes in addition silicones contains

A

Silicone polymers that have many Vinyl groups

73
Q

Addition silicon is supplied in 3 forms

A

Two paste system
Gun-and-cartridge system
Heavy putty

74
Q

One of the 3 forms of supply of addition silicon where

Base and catalyst are dispersed from side by side

A

Gun-and-cartridge system

75
Q

One of the 3 forma of supply of addition silicon that

Is used in the PUTTY-WASH technique.
Base and catalyst in plastic tubes
Putty scooped out and mixed by hand

A

Heavy Putty

76
Q

T or F

Addition silicons are hydrophobic materials

A

True
This characteristic has led to some problems with air bubbles trapped on the surfaceof the impression when pouring gypsum cast and dies

77
Q

Advantages of addition silicone

A

Accurate
Ease of use
FAST SETTING
Wide range viscosities

78
Q

Disadvantages of addition silicon

A

Hydrogen evolution - can result in pinpoint voids in the gypsum casts

TO COMPENSATE FOR THE HYDROGEN GAS, wait for an HOUR OR MORE before pouring the impression

79
Q

Reaction of addition silicone

A

Hydrogen containing silohexane + vinyl terminal + chloroplatinic acid ➡️ silicone rubber

80
Q

What elastomer has the LOWEST DIMENSIONAL CHANGE from all impression materials

A

Addition silicone

81
Q

Elastomer that has superior accuracy

A

Addition silicone

82
Q 
T or F
Addition silicone has 
Short working time
Low flexibility 
Less tissue reaction
A

True

83
Q

T or F
In addition silicone, silicones are HIGHLY HYDROPHOBIC. Surface is poorly wetted by water with CONTACT ANGLE OF 90 deg which INCREASES surface bubbles

A

True

84
Q

Stiffest type of elastomer

A

Polyether

85
Q

Name of this elastomer is derived from the fact that they are composed of POLYETHER POLYMER MOLECULES

A

Polyether

86
Q

Polyether is used for what kinds of work

A

Crown and bridge work, partial dentures, implants and overdentures

87
Q

Composition of base paste of polyether

A

Polyether

Filler

88
Q

Composition of catalyst paste of polyether

A

SULPHONIC ACID ESTER

89
Q

Composition of catalyst paste of polyether that enhances further polymerization and crosslinking of the polymer chains during chemical reaction.
Reaction is responsible for transforming PASTE TO STIFF POLYETHER RUBBER

A

Sulphonic acid ester

90
Q

Full arch impression made from these materials may be difficult to remove from the mouth because of its stiffness

A

Polyether

91
Q

Advantages of polyether

A

Accuracy
Ease of use
GOOD ON UNDERCUTS

92
Q

Disadvantages of polyether

A

Sulphonic acid ester cause allergic reactions
Poor tear strength
Rapid setting time
Stiff set material

93
Q

Reaction of polyether

A

Polyether + sulphonic ester ➡️ cross-linked rubber

94
Q

Elastomer that has the SHORTEST WORKING TIME

A

Polyether

95
Q

Elastomer that has
Less permanent deformation
LOW FLOW, HIGH STIFFNESS
and absorbs water, dried after disinfecting

A

Polyether

96
Q

T or F

In elastomers, Working and setting time DECREASES as viscosity INCREASES

A

True

97
Q

All materials change dimensionally.
Changed is greater for POLYSULFIDE and CONDENSATION SILICONE.
Stored impression must be kept in a dry cool environment

A

Dimensional stability

98
Q

Rubber impression materials capable of reproducing details

A

Reproduction of details

99
Q

T or F

Elastic properties of elastomers improve with an INCREASE IN CURING TIME in the mouth

A

True

100
Q

The LONGER the impression can remain in the mouth, LESS distortion upon removal

A

Elasticity

101
Q

Ranking of tear strength from lowest to higest

A

Hydrocolloids (agar and alginate)
Silicones ( CS and AS)
Polyether
Polysulfide

102
Q

Probability of allergic/toxic reactions is small

A

Biocompatibility

Contact dermatitis from POLYETHER has been reported

103
Q

Properly compounded-does nit deteriorate

A

Shelf life

104
Q

Mixing and handling

T or F
Equal lengths of base and catalyst dispensed but not touching

A

True

105
Q

Mixing and handling
T or F

Viscous nature - stiff tapered steel slatula is used to mix

A

True

106
Q

Mixing and handling
T or F
First Catalyst paste is picked up on spatula, add to base, mix for 10 secs, circular motion

A

True

107
Q

Mixing and handling
T or F
Material is wiped across entire surface of pad with pressing motion

Aim is to produce HOMOGENOUS creamy consistency

A

True

108
Q

Mixing and handling
T or F
Material can be loaded in syringe or the setting tray

Elastomers often use acrylic custom tray

A

True

109
Q

Mixing and handling
T or F
Elastomeric impression should be removed from mouth with steady force

A

True

110
Q

Failure to produce acceptable gypsum is associated with error in mishandling rather than deficiency in material properties

A

Effects of mishandling

111
Q

Pastes supplied in two cylinder tubes mounted side by side

Second tube contains PLASTIC PROPELLER TYPE ASSEMBLY attached to end of cylinder tubes

A

Gun and cartridge system

112
Q

T or F

In gun and cartridge system, as material is extruded, two diff pastes are mixed together to produce homogenous material

A

True

113
Q

Syringe- inject material around tooth prep

While the assistant load the impression tray material dispensed directly form the gun

A

Gun and cartridge system

114
Q

Cleanup of spatula is easy, just…

A

Wait for material to set then peel off

115
Q

Certain elastomeric materials should be poured asap except for

A

Addition silicone and Polyether

116
Q

Delay pouring of addition silicone for atleast

A

45 mins to 1hr

117
Q

What will happen If impression is poured too soon

A

It will produce tiny bubbles on surface

118
Q

T or F

Delay in pouring has no effect on dimensional stability

A

True

Dent Mat 1 (1 decks)

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