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Operative I > Week 5 Biomaterials > Flashcards

Week 5 Biomaterials Flashcards

1
Q

what are the ways to classify composites

A

-filler particle size and distribution
-handling characteristic
-activation/type of polymerization

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2
Q

what is the history of tooth colored materials

A

-1870s silicate cement: high solubility
-1940s polymethyl methacrylate (PMMA)
-composite resin 1960s

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3
Q

what is composite

A

material containing at least 2 components (phases) with distinct chemical and physical properties that after blended, they show unique and superior properties as compared to the individual components

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4
Q

what is dental composite

A

resin matrix phase reinforced by dispersed filler particle phase bound to the resin by a silane coupling agent

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5
Q

what are the uses for dental composite

A

-tooth colored restorative material
-bonding agents
-sealants
- composite resin luting agents
- resin modified glass ionomer material
-light activated liner materials
-CAD/CAM blocks
-resin endodontic sealers

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6
Q

what does dental composite packaging consider

A

protection against visible light and moisture, allows oxygen though

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7
Q

what are the components of dental composite

A

-resin matrix
- filler particles
-coupling agent
-activator-initiator system
-pigments and other compounds

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8
Q

what makes up the resin matrix

A

-Bis GMA
-UDMA
-TEGDMA

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9
Q

what are the filler particles

A

crystalline silica, Ba, Li, Al silicate glass, amorphous silica

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10
Q

what are the benefits of filler particles

A

-reinforcement of resin matrix
- decreased polymerization shrinkage
- decreased thermal expansion and contraction
- viscosity control
-decreased water sorption
- increased radiopacity

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11
Q

what does higher filler amount reduce

A

the thermal expansion and contraction coefficients

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12
Q

reduced polymerization shrinkage is proportional to…

A

filler volume

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13
Q

what does the coupling agent do

A

strongly binds the filler to the resin matrix

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14
Q

what are the benefits of coupling agent

A

-better stress distribution between resin matrix and filler particles
- improves the mechanical properties
- decreased water sorption along filler resin interface

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15
Q

activator + initiator = _____

A

free radicals

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16
Q

composites: monomers to be converted into ____

A

polymers

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17
Q

what is the process of monomers to polymers triggered by

A

free radicals

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18
Q

what are the steps in reaction of polymerization

A

-activation
- initiation
-propagation
-termination

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19
Q

what does the polymerization inhibitor do

A

-prevent spontaneous polymerization
-stop polymerization from brief room light exposure
- once the blue light is used, all inhibitor quickly consume - polymerization chain reaction starts
- increase the shelf life of the composite resin

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20
Q

what are examples of polymerization inhibitors

A

BHT and hydroquinone

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21
Q

what are the optical modifiers

A

-pigments: metal oxides
-opacifiers: titanium and aluminum oxide

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22
Q

what are the classes of filler size and dsitribution

A

-macrofill
-midfill
-microfill
-hybrids

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23
Q

describe macrofill and midifill composites

A

-large fillers
-not good size distribution
-prone to staining

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24
Q

describe microfill composite

A

-excellent finish
- low mechanical and surface properties
-use for esthetic, low stress sites

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25
Q

describe hybrid composites (midi-micro)

A

-imrpoved surface finish
-high strenght
- universal composites

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26
Q

describe hybrid composites (mini-micro)

A

-newer material
- smoother finish
- slightly lower strength

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27
Q

what are the brands of macrofill and midifill

A

adaptic and concise

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28
Q

what are the brands of microfill

A

durafill VS, epic TMPT, renamel, heliomolar

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29
Q

what are the brand of midi-micro hybrid fill

A

TPH

30
Q

what are the brands of mini-micro hybrid fill

A

-EsthetX

31
Q

what are the brands of mini-nano hybrid fill

A

filtek supreme ultra

32
Q

what are the classifications by handling characteristics

A

-flowable
- packable

33
Q

describe flowable composite

A

-low viscosity hybrid reduced filler
- 40-60% adapts better without handling
- lower filler percentage, increased flexibility
- many are not radioopaque

34
Q

when are flowable composites used

A

under conventional composite at gingival floor of class 2

35
Q

why is lack of radiopacity a problem

A

difficult to distinuguish from recurrent caries

36
Q

what is flowable composite made of

A

barium, strontium, zirconium filler

37
Q

compare flowable vs packable

A

-flowable: more shrinkage, less stress
-packable: higher filler, high or medium viscosity, high stress

38
Q

what increments do you used bulk fill in

A

5 mm

39
Q

describe bulk fill

A

-pre-polymerized particles, higher size fillers
- more translucent filler particles

40
Q

what are the classes of polymerization activation

A

-self-cure
-light cure
-dual cure

41
Q

what are the advantages and disadvantages of light cure composite

A
  • advantages: mixing not required, less porosity, increased strength. aliphatic amine more color stable than self cure. better control of working time
    -disadvantages: limited light penetration, greater than 2 mm increments, 20 sec. blue light, retina damage- use orange shield
42
Q

what are the procedural factors for light cure variables

A

-exposure time
-tip size- smaller tip = increase output, increase heat
- distance: decrease output when you increase distance

43
Q

what are the types of curing units

A

-quartz-tungsten-halogen
- plasma arc
- laser
- LED

44
Q

what are the factors that reduce light output

A

-degradation
-tip contamination by resin buildup
- sterilization problems
- infection control barriers

45
Q

describe the oxygen inhibited layer

A

15 microns thick, on the outer layer which facilitates addition and wetting of subsequent layers

46
Q

just cured composites may have 50% of the ____

A

unreacted methacrylate groups to co-polymerize with the newly added material

47
Q

do older restorations have unreacted methacrylate

A

no

48
Q

what are the important properties of dental composite

A

-polymerization shrinkage and stress
- wear resistance
-surface finish
- marginal infiltration
-water sorption
-radiopacity
-color stability

49
Q

what does the polymerization yield

A

shrinkage and consequently stress at the composite tooth interface

50
Q

what does stress level vary by

A

the type of restoration configuration factor, C-factor

51
Q

what is C-factor

A

bonded/unbonded surfaces

52
Q

higher c-factor, higher ____

A

stress

53
Q

what is c factor in incremental placement

A

low

54
Q

is shrinkage reduced in incremental placement

A

no stress is reduced

55
Q

what is the polymerization rate of self cure composite

A

slower

56
Q

do composites shrink towards the light in light directed polymerization

A

no

57
Q

biofilm formation =

A

bacterial acids = soften of resin matrix

58
Q

higher filler amount =

A

higher wear resistance

59
Q

what is marginal infiltration decreased with

A

improvement of adhesive systems

60
Q

where is the failure gap in marginal infiltration

A

tooth and composite

61
Q

what happens in marginal infiltration

A

secondary caries, marginal staining and fracture, post op sensitivity

62
Q

lower filler amount and higher water sorption =

A

higher expansion

63
Q

which has higher absorption BisGMA and TEGDMA or UDMA

A

BisGMA and TEGDMA

64
Q

when does color change

A

2-5 years

65
Q

what causes color change

A

food, smoking, beverages

66
Q

what are adhesive systems

A

agents that bond micromechanically or/and chemically the restorative material to tooth substrate through an interfacr

66
Q

what are adhesive systems

A

agents that bond micromechanically or/and chemically the restorative material to tooth substrate through an interface

67
Q

what does etching do

A

-to remove the minerals from dental substrate exposing the collagen
- allowing adhesive infiltration

68
Q

what does bonding do

A

-adhesive application- infiltration
- encapsulation of dentin collagen matrix
- after polymerization: micromechanical interlocking
-outer layer co-polymerizes with composite material

69
Q

what is the mechanism of action in chemical bonding

A

a phosphate monomer that chemically interacts via ionic bonding to calcium in hydroxyapatite

Operative I (12 decks)

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