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Composite resins Flashcards

(65 cards)

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1
Q

What are the three types of components every compost has

A

Resin Matrix, Inorganic filler, and coupling agents

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2
Q

What (in general) makes up the resin matrix

A

monomer, initiator, inhibitors, pigments

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3
Q

How do the inorganic fillers affect cmpsts

A

creates strength, more filler ore strength

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4
Q

How can composites be classified

A

by monomer type, or filler particle type

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5
Q

What are two types of monomers

A

Methacrylate

silorane

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6
Q

What are the 4 types of compost particle

A

macrofil, microfilm, hybrid, nano

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7
Q

What do monomers due?

A

binds filler particles together providing workability.

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8
Q

What kind of money is sometimes mixed in with BisGMA to lower viscosity

A

TEGMA

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9
Q

What are the three steps of polymerization

A

Initiation
propagation
termination

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10
Q

What happens during initiation

A

chemical, light, or heat stimulus produce reactive free radicals

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11
Q

what happens during propagation

A

monomer units going due to free radical to form polymer network (think dominoes falling)
yields 50-60% conversion

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12
Q

Whats the average shrinkage noted with polymerization

A

1-6%

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13
Q

what is a good % by weight for composites..% by volume

A

50-86% by weight 35-71% by volume

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14
Q

what features give your composites less wear?

A

Smaller partial size to decrease abrasion
heavier filled to decrease attrition (large chunks breaking off)
non contact areas
less restoration surface area
restoration in anterior v posterior
higher cure

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15
Q

what do coupling agents do?

A

chemically bond filler particles to matrix

transfers stresses overal strength increases

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16
Q

what are the advantages of using light activation

A

longer working time
greater polymerization
reduced porosity
better color stability

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17
Q

what is the disadvantage to using a light cured resin

A

limited depth of cure

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18
Q

what are the two chemicals used in chemical activation

A

initiator-benzoyl peroxide

activator tertiary amine

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19
Q

Where do the radicals attack during polymerization

A

double carbon bonds of the resin

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20
Q

microfil have what particle size

A

40-50nm

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21
Q

nano composites have what particle size range

A

5-100nm

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22
Q

what are the micro hybrid particle sizes

A

.6 - 1 microns plus 40 nm particles

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23
Q

How does particle size affect polishability

A

smaller particles finer polished

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24
Q

do microfilms have a coupling agent

A

no, so inferior properties
also radiolucent
ok for class 5

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25
Z250 is what class
microhybrid
26
what coupling agent do nano composites use
silane
27
what kind of filler distribution do nano composites have
broad with high loading increasing stregnth
28
What aspect of nano composites increases polish retention
addition of nanometer filler particles
29
Filtek supreme ultra is what % by weight filled
78%
30
What are the two types of filler particles in Filtek Supreme Ultra
nanomers .02-.07 microns nano clusters the act as single unit .6-1.4microns
31
controlled clinical studies say what when comparing wear of micro hybrid and nanofil
no sig difference in wear after 5 years but nanofil maintained a better polish
32
Whats the difference between nano composites and nanohybrid
composite has just nanometer sized particles throughout matrix whereas hybrids also have conventional fillers like sillica
33
What composite has the best flexural strength
Z250
34
whats a drawback of Z250
higher polymerization shrinkage 3%
35
how does composite clinical behavior comapre
limited studies short observation times large differences not easily demonstrated
36
What is a newer developed monomer that supposedly decreases shrinkage
Silorane
37
What is silorane
a ring monomer that opens during reaction. | uses camphorquinone and iodonium salt initiation
38
does shrinkage matter?
Clinical study showed no advantage between siloxane v methacrylate in 5 year study
39
Why are flowable composites flowable
less filler content and less viscous monomers (TEGMA)
40
How do flowables compare to hybrids
mechanical properties are less and polymerization shrinkage is higher
41
Do liners under direct composites improve marginal integrity or reduction of post op sensitivity
no clinical evidence for either
42
Can flowables be used in class one preps
Controlled clinical studies showed no difference at two years between flowable and a nano fill similar results for class 2 restorations
43
do self adhesive flowables work
less shear bond strength than etch/adhesive
44
How does heating affect composites
reduces viscosity but doesn't seem to affect other properties
45
when testing depth of cure what must be the hardness of the deepest level to be considered cured
80% of top hardness
46
how does depth of composite affect cure
deeper composites attenuate the light decreasing the cure (same with darker shades)
47
what happens to cusps deflection with bulk placement
Increased due to C factor, but this may not be clinically significant
48
which type of fill has been shown to contain greater porosity: Incremental or bulk
Incremental
49
what properties might increase depth of cure for a composite
increased translucency, additional photo initiators, just more photo initiators
50
what is sonic fill
Single step bulk fill, using trigger sided cure can get up to 5mm, sonic activation decreases viscosity but its expensive
51
How do stress reducing monomers work
use fragmenting monomers that can break during polymerization reducing the stress on the prep.
52
Are bulk fill flowables a definitive restoration
No, Require covering by a restorative composite. they are very translucent. overall lack of clinical studies
53
what are some advantages of dual cure composites
unlimited depth cure less stress (but greater shrinkage) due to slower cure less porosity because its bulk fill equivocal fracture toughness
54
What are some disadvantages of dual cure bulk fill composites
color stability. Amines can discolor over time its incompatible with simplified bonding agents 2x microleakage
55
what was the northern lights consensus statement on light cured bulk fill composites as far as advantages
may reduce placement time may reduce air voids may have stress reduction
56
what was the northern lights consensus statement on light cured bulk fill composites as far as disadvantages
may need more than one increment depending on depth need supplemental cure from buccal and lingual learning curve may not be as esthetic due to translucency
57
are composites bio comparable to the pulp
yes with good seal
58
are there allergic reactions to composites
rarely with hema
59
any cytotoxicity of composities
maybe but short lived so not a chronic source
60
from a biocompatibility standpoint why is degree of cure important
decreases free monomer.
61
Whats BPA
Bisphenol A Acts like estrogen disruption in animal hormone activity but role in human hormone yet to be determined
62
BPA and dental resins
BPA used to make most resins salivary enzymes breakdown bis dma detected in saliva and urine in minute amount overall much less than consumer item
63
how can reduce boa exposure
rubber damn | remove air inhibited layer
64
study of BPA urinary concentrations
Transient increase in BPA concentration that was no longer detectable at 14 days
65
ADA position onBPA
unwanted concern

Dental Materials (9 decks)

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