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Dental materials > L4 Resin based composite > Flashcards

L4 Resin based composite Flashcards

1
Q

what is the composition of a resin based composite “?

A

1.) resin component
2/) reinforcing fillers
3.) saline coupling agents
4.) initiator ( light activator )
5.) inhibitor
6.) optical modifires

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2
Q

what is the resin matrix made up of?

A

bis-GMA
UDMA
TEGMA

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3
Q

what factors play a role in increasing viscosity during setting process?

A

size of monomer and co-polymer

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4
Q

which component of the resin matrix is extremely viscous ?

A

bis-GMA

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5
Q

why is UDMA and TEGMA added to resin matrix ?

A

to decreases bis-GMA resin vescocity and increase degree of converstion

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5
Q

why is UDMA and TEGMA added to resin matrix ?

A

to decreases bis-GMA resin vescocity and increase degree of converstion

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6
Q

what are resin composites classified based on?

A

their filler particle size

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7
Q

what are the major roles of filler components ?

A

reduce amount of resin matrix which helps control shrinkage of composite during polymerization

increase hardness and strength

reduce wear , water sorption and staining

increase viscosity

  • Filler are radiopaque so radiopacity for visualization on x-ray
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8
Q

what is the % of filler particles by weight and by volume

A

by volume 30-70%

by weight 50-85%

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9
Q

what is the function of a coupling agent ?

A

binds resin matrix and filler particles together .

roles and benefits of filler particles can only be achieved if it is coupled strongly with resin matrix

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10
Q

what is a common light activator and what wavelength is used to activate it ?

A

camphorquinone , activated by visible blue light (400-500nm) 468

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11
Q

what is an inhibitor commonly used in light activated composites
?

A

butylated hydroxytoluene

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12
Q

what is the role of an inhibitor ?

A

prolongs shelf life of product

prevent propagation and reacts with free radicals

ensure sufficient working time and extend resin storage life

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13
Q

what is the role of optical modifiers ?

A

materials used to help achieve desired shade by adding small amounts of metal oxide ( aluminum and titanium dioxide)

darker shades should be applied in thinner layers

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14
Q

how are both chemically (self-cured) and light activated composites polymerized?

A

through action of free-radical polymerization and addition reaction

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15
Q

how many pastes are used in the chemically activated composites ? and how many are used in the light cured system ?

A

it is a two paste system while light cured systems only use one paste

16
Q

what reaction occurs in light cured composites in order to start initiation ?

A

camphor quinone reacts with amine activator in order to form free radicals. these free radicals then break double carbon bonds to start process of polymerization

17
Q

what is the typical degree of conversion ( from monomer to polymer ) when using resin based composie?

A

50-70%

18
Q

what is the C(configuration) factor ?

A

ratio of bonded to unbonded walls . indicates potential for development of stress

19
Q

what is the thermal conductivity and expansion of resin composites when contrasted with enamel and dentin ?

A

thermal conductivity is almost the same while thermal expansion is slightly more than that of enamel and dentine

20
Q

mechanical properties of resin composite is dependent on ?

A

filler content and type , and the efficiency of the coupling agent ( most composites have good mechanical properties but fail in tension )

21
Q

how do resin composites attach to the tooth ?

A

via mechanical bonding

22
Q

what is the minimum bond strength required to prevent marginal gap formation?

A

20Mpa

23
Q

what is the composition of a resin based composite “?

A

1.) resin component
2/) reinforcing fillers
3.) saline coupling agents
4.) initiator ( light activator )
5.) inhibitor
6.) optical modifiers

24
Q

how is composite bonding achieved ?

A

acid-etch technique

chemical adhesion

single bottle system

25
Q

what type of filler has the highest wear resistance ?

A

Mirco-hybrid have highest wear resistance

26
Q

what material is most likely going to be used to fix anterior teeth for aesthetic reasons >?

A

resin based composite because they have a Varity of shade options and good marginal adaptations

27
Q

what is a flowable composite ?

A

Hybrid composite with reduced filler level
and a narrower particle-size distribution to increase flow and
promote intimate adaptation to prepared tooth surfaces. Flowable composites are often used as the first layer of a cavity filling
to improve filling adaptation to the cavity.

Dental materials (15 decks)

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