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Dentistry Module 3 > dental materials > Flashcards

dental materials Flashcards

1
Q

what is light curing

A

: a dental curing light is a piece of dental equipment that is used for the polymerization of light cure.

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2
Q

describe polymerization in dentistry

A

In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks.

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3
Q

a substance which has a molecular structure built up chiefly or completely from many similar units bonded together. - best describes what

A

a polymer

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4
Q

is a polymer that changes its properties when exposed to light, often in the ultraviolet or visible region of the electromagnetic spectrum. - best describes what

A

a photopolymer

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5
Q

: is the action of changing a mixture of monomers, oligomer and photo initiators that conform into a hardened polymeric material. - best describes what

A

curing

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6
Q

is a material made from two or more different materials that, when combined, are stronger than those individual materials by themselves. - best describes what

A

composite

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7
Q

a solid or liquid synthetic organic polymer used as the basis of plastics, adhesive, varnishes, or other products. - best describes what

A

Resin

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8
Q

are certain materials that are placed in dental composites to reduce shrinking upon curing. - best describes what

A

fillers

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9
Q

what is the purpose of a coupling agent in a resin composite

A

The coupling agents act as an adhesion promoter. Coupling agents are activated when activated by a light curer.

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10
Q
  • Hard and lustrous (shiny)
  • Closely packed crystalline structures
  • Opaque
  • Conductors of heat and electricity except mercury (Hg)

features above best describe metal at what state

A

metals at ambient temperature

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11
Q

alloys are a mixture of two or more metals

what is the name of an alloy with two and three metals

A

two metals - binary alloy

three metals - ternary alloy

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12
Q

what is the name of the system that shows all possible combinations of an alloy

A

alloy system

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13
Q

the initial process that occurs in the formation of a crystal from solution, a liquid, or a vapour, in which small number of ions, atoms, or molecules become arranged in a pattern characteristic of a crystalline solid. Forming a site upon which additional particles are deposited as the crystal grows. - is known as what

A

nucleation

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14
Q

The reaction between mercury and alloy when mixed together is termed an ?

A

amalgamation

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15
Q

the maximum degree of extension in response to an applied tensile force - is the definition of

A

ductility

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16
Q

the maximum degree of compression in response to an applied compressive force. - is the definition of what

A

malleability

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17
Q

alloy and mercury produces amalgam, what is this a process of

A

amalgamation

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18
Q

viable alternatives for material and concerns over safety and enviromnetal pollution has seen the reduction of which dental restoration material

A

amalgam

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19
Q

65% Ag, 29% Sn (tin), 6% Cu, 2% Zn, 3% Hg (mercury) represents the composition of which amalgam, the conventional or the more typical one.

A

conventional

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20
Q

40% Ag, 32% Sn (tin), 30% Cu, 2% Zn, 3% Hg (mercury) represents the composition of which amalgam, the conventional or the more typical one.

A

the typical one

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21
Q

40% Ag, 32% Sn (tin), 30% Cu, 2% Zn, 3% Hg (mercury) is the composition for amalagam

what purpose does the Ag and Sn have

A

undergoes setting reaction

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22
Q

40% Ag, 32% Sn (tin), 30% Cu, 2% Zn, 3% Hg (mercury) is the composition for amalagam

what purpose does the Cu have

A

strengthening effect on amalgam

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23
Q

40% Ag, 32% Sn (tin), 30% Cu, 2% Zn, 3% Hg (mercury) is the composition for amalagam

what purpose does the Zn have

A

Zn (zinc) acts as a scavenger, preventing oxidation of other metals.

zinc oxide

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24
Q

amalgam undergoes dimensional changes during the setting period.

how long does it take for amalgam placement to function

A

15-20 mins

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25
Q

amalgam undergoes dimensional changes during the setting period.

how long does it take for amalgam placement to undergo final strength

A

24 hours

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26
Q

amalgam is at its strongest under compression.

but when is amalgam at its weakest

A

tension and shear

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27
Q

what is defined as a time dependant plastic deformation under constant stress occuring in crystalline materials

A

creep

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28
Q

how does creep affect the margins of the cavity

A

creep causes the amalgam to flow, such that unsupported amalgam protrudes out from the margins of the cavity

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29
Q

creep results in unsupported amalgam protruding out from the margins

resulting in unsupported edges. these edges become weak what other factor may weaken them.

A

corrosion

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30
Q

the formation of a ditch around the margins of amalgam restorations are caused by what

A

crosion of the unupported edges through creep.

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31
Q

a marginal seal between the margins of the cavity and the amalgam is sealed by what

A

corrosion products

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32
Q

what reacts with the exposed amalgam to cause corrosion

A

electrolytes of saliva

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33
Q

why is it important to place a varnish, liners or a base in the cavity before an amalgam restoration

A

amalgam is 2.5* more thermal conductive than normal tooth. this ensures the pulp is protective.

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34
Q

what is the danger of Hg in the human body

A

Hg known to be toxic to the CNS

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35
Q

polymerisation of resin composites undergo the 4 following stages

A

activation

initiation

propagation

terminationn

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36
Q

during polymerisation composite material contracts to bring about an exothermic or endothermic reaction

A

exothermic reaction

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37
Q

which material is better for matching tooth shade. resin composite or acrylics

A

acrylics

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38
Q

what is the purpose of using a inert filler

A

to reduce shrinking

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39
Q

what reduces the mobility of the unreacted monomers

A

resin matrix

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40
Q

what are siloraines used for

A

used to lower shrinking during polymerisation

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41
Q

glasses

silica

quartz

are all examples of what

A

types of fillers in resin composite

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42
Q

how does the increase in percentage of filler content by volume, affect the surface hardness

A

increases surface hardness

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43
Q

how does the increase in percentage of filler content by volume affect the “percentage of volume setting contraction”

A

increase in filler volume decreases setting contraction

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44
Q

how does the increase in percentage of filler content by volume affect the “cofficent of thermal expansion”

A

as the filler volume increases

this decreases coefficent of thermal expansion

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45
Q

what is the name given to something that is a photoinitiator used in curring dental composites

A

camphorquinone

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46
Q

what affect does camphorquinone have on free radicals

A

it yields the necessary free radicals to start polymerisation

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47
Q

at what spectrum does dental composite get excited

A

460-480 nm (blue light)

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48
Q

resin and filler are completley useless without which agent

A

coupling agent

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49
Q

what does the coupling agent convert the brittle filler to

A

flexible and ductile polyermer matrix

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50
Q

what would type 1 resin composites be used for

A

restoration of cavities involving occlusal surfaces

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51
Q

porosity is the air bubbles present in dental materials

what does the increase of porosity have on the strength and fatigue of resin composites

A

decrease in strength and fatigue

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52
Q

if there is a decrease in coupling agent, how does this affect the strength and fatique

A

decreases strength and fatique by 30%

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53
Q

does cavity shape influence the overall success of restoration

A

yes

C factor = number of bonded surfaces

number of un-bounded surfaces

54
Q

how does food and plaque acid affect the resin matrix

A

initiates chemical softening

55
Q

crack propagation is brought about by stress concentrations where

A

at the surface resin composite or fillers

56
Q

how does increase in porosity affect rate of crack propagation

A

increases crack propagation

57
Q

glass polyalkenoate is formly known as what

A

glass ionomers

58
Q

polycarboxylate cement has been used as a filling material as alternative to which restoration material

A

amalgam

59
Q

powder and liquid, powder mixed with water and encapsulated form are example of how a particular material is supplied. what is the name of the material

A

glass polyalkenoate

60
Q

what would increase the porosity of fluid cements

if mixed by hands

or mixed mechanically

A

more porosity if mixed mechanically

think froth development

61
Q

glass polyalkenoate setting reaction has two phases

initial set

final set

what are the times for each set

A

initial set - first few minutes

final set - 24 hours after completion

62
Q

what are the implications for clinicians when working with glass polyalkenoate

A

delay final finishing for atleast 24 hours

material sensitive to moisture until final set is complete

63
Q

how does polyalkenoate properties thermal diffusivity relate to dentine

A

close to dentine

64
Q

what effect does polyalkenoate have on fluride

A

polyalkenoate releases and uptake

65
Q

varnish and adhesive sealers are examples of what

A

cavity sealers

66
Q

glass ionomer is an example of a cavity sealer or liners

A

cavity liners

67
Q

zinch phosphate cement

reinforced zinc oxide

zinc polycarboxyl cement

glass ionomer cement

the above are examples of liners or bases

A

bases

68
Q

provides a protective coating and barrier to leakage

coats walls of the cavity

the above is describing what

A

cavity sealers

69
Q

seals the dentinal tubules and reduces the leakage around a restoration

provides no thermal insulation

the above best describes what type of sealer?

A

varnish sealer

70
Q

provides sealing as well as bonding at the interface between restoration and cavity preparation walls

the above best describes which type of cavity sealer?

A

adhesive sealers

71
Q

it is a liquid in which CaOH are suspended in a solution of natural or synthetic resin

the above is a definition of what

A

cavity liners

72
Q

is dycal a cavity sealer or cavity liner

A

liner

73
Q

dycal acts as a thin barrier between the restoration and the remaining dentine. this prevents irritation in the form of physical, mechanical, biological and chemical to what part of the tooth

A

pulpal tissue

74
Q

does dycal provide thermal insulation

A

no

75
Q

can you apply dycal on cavity margins

A

no

76
Q

dycal stimulates the production of dentine, which type of dentine does it stimulate be specific

A

stimulates secondary dentine

stimulates tertiary dentine - reparative dentin

77
Q

in terms of restorative material, what is the benefit of using dycal as a liner

A

it is compatible with all type of restorative material

78
Q

what is the most common direct pulp capping agent

A

calicum hydroxide

CaOH

79
Q

what is the purpose of direct pulp capping

A

to seal communication between the root cancal system and the external tooth surface at all levels

80
Q

phosphoric acid based cements setting reaction time is rapid or slow

A

rapid

81
Q

phosphoric acid based cements reaction is exothermic or endothermic

A

exothermic

82
Q

phosphoric acid based cements take how long to fully solidify

A

4-7 minutes

83
Q

phosphoric acid based cements, can they be seen in an x-ray

A

no they are radiolucent

84
Q

is the pH of phosphoric acid based cements high or low

A

low

85
Q

if a cavity sealer or liner has a non obtundant effect what does that mean

A

it means that the material doesnt blunt the irritation or lessens the pain.

86
Q

what would cause coronal leakage

A

if the liner material has no adhesive affect, this would NOT FORM a coronal seal

87
Q

is phosphoric acid based cements adhesive or not

A

non adhesive

88
Q

zinc oxide eugenal cements come in the form of 2 paste what are they

A

zinc oxide and accelerator

89
Q

zinc oxide eugenal cements is bacteriocidal. what property causes this

A

the zinc in zinc oxide eugenal cements is bacteriocidal

90
Q

can zinc oxide eugenal cements be seen in x-rays

A

no they are radiolucent

91
Q

zinc oxide eugenal cement are compatible with resin composites yes/no?

A

no they are incompatible

92
Q

are zinc oxide eugenal cements adhesive

A

no they are not, so therefore no coronal seal

93
Q

calcium hydroxide cements come in the form of 2 paste what are they

A

paste 1 - a glycol salicylate

paste 2 - zinc oxide with calcium hydroxide

94
Q

calcium hydroxide cements are activated by what

A

light

95
Q

calcium hydroxide cements has a high pH, what affect does this have on bacterias

A

bacteriocidal affect

96
Q

can calcium hydroxide cements been seen in x-rays

A

no radiolucent

97
Q

why would calcium hydroxide cements not be used for amalgam restorations

A

insufficient strength to withstand amalagam condensation/packing

98
Q

can calcium hydroxide cements provide a coronal seal

A

no, calcium hydroxide cements are not adhesive

99
Q

polycarboxylates comes in the form of what powder or liquid

A

powder

100
Q

what is the powder form of polycarboxylates

A

zinc oxide

101
Q

polycarboxylates has the ability to release fluroride, what affect does this have on bacteria.

A

bacteriostatic

102
Q

can polycarboxylates provide a coronal seal

A

yes, polycarboxylates are adhesive

103
Q

what does RMGIG also known as

A

vitrebond

104
Q

glass ionomers have a bacteriostatic property, what must glass ionomers have or do to have that bacteriostatic property

A

release fluoride

105
Q

are glass ionomers adhesive or not

A

they are adhesive

106
Q

the advantage of adhesion of a restorative material would be the absence of marginal gaps between the restoration and tooth surface

what would this minimise

A

microleakage and development of secondary caries

107
Q

the state in which two surfaces are held together by interfacial forces: is the definition of what

A

adhesion

108
Q

is a material, frequently viscous fluid, that joins two substrates together and solidifies, and is able to transfer koad from one surface to the other is an example of what:

adhesion

adhesive

adherend

A

adhesive

109
Q

this referrs to the surface or substrate that is adhered to

A

adherened

110
Q

there are three nechanism of adhesion what are they:

A

mechanical adhesion

adsorption adhesion

diffusion adhesion

111
Q

interlocking of the adhesives with irreularities in he surface of the substrate or adherent: is an example of what mechanism of adhesion

A

mechanical adhesion

112
Q

chemical bonding between the adhesive and adherent: is an example of what mechanism of adhesion

A

adorption adhesion

113
Q

interlocking between mobile molecules: is an example of what mechanism of adhesion

A

diffusion adhesion

114
Q

penetration of resin and formation of resin tags within the tooth surface: is an example of what mechanism of adhesion

A

mechanical

115
Q

chemical bonding to the inorganic compound (hydroxyapattite) or organic components (type 1 collagen): is an example of what mechanism of adhesion

A

adsorption

116
Q

precipitation of substances on the tooth surfaces to which resin monomers can bond mechnically or chemically: is an example of what mechanism of adhesion

A

diffusion

117
Q

by having a clean surface

good coverage of adhesive on all surfaces

and adhesive should be well cured

will enable what

A

the following were requirements of achieving good adhesion

118
Q

the transformation of the smooth enamel to irregular surface, resulting in increase in surface energy is achieved by what

A

acid etch

119
Q

when a fluid resin-based material is applied to the etched surface, the resin penetrates on to the surfaces, aided by what?

A

capillary action

120
Q

what must the monomers undergo for the material to be interlocked with the enamel surface

A

polymerised

121
Q

factors affecting etch time:

why must adequate drying be done after washing the etch

A

this would enable the hydrophobic resin to penetrate and attach to the demineralised dentine

122
Q

dentine bonding problems

why is the dentine being hydrophilic a problem

A

adhesives are hydrophobic

  • the use of primers helps with composite materials
123
Q

what is the name of the acid that works as a dentine conditioner

A

primer

124
Q

what is the fucntion of a primer

A

alters surface appearance and characterisitics of dentine

125
Q

what is the function of sealers

A

flow in to the dentinal tubules

seals dentine with a surface layer

ensures bonding to resin in the composite

126
Q

how do dentine conditioners work

A

they perform an acid base reaction with hydroxyapatite

open dentine tubules

demineralize surface detine to a depth of 4 microns

127
Q

what bonds hydrophobic composites to hydrophilic dentine

A

primers

they act as adhesives

128
Q

children under 15 years

pregnant women

breast feeding

these are all contraindications of what

A

uses of dental amalagam no longer used for

129
Q

where is amalagam natrually occuring from

A

volcanic eruptions

130
Q
A

Dentistry Module 3 (33 decks)

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