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Operative II > Week4 - Composites > Flashcards

Week4 - Composites Flashcards

1
Q

what are the ways to classify composites

A
  • filler
    -handling
  • activation
    -curing light units and concepts
  • properties of dental composites
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2
Q

what was used in 1870’s and describe

A
  • silicate cement
  • high solubility
  • severe surface wear
    -low mechanical properties
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3
Q

what was used in 1940s and describe

A

-PMMA
- unfilled
- high curing shrinkage
- thermal expansion and contraction
-stress at the cavity margins and severe marginal leakage
- poor wear resistance
-staining

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4
Q

what was used in 1960s and describe it

A

-composite resin
- BisGMA
- fillers bonded
- low thermal coeffeicient of expansion
- dimensional change on setting
- higher wear resistance
- improved clinical performance

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5
Q

what is the definition of composite

A

a material containing at least two components with distinct chemical and physical properties that after blended show unique and superior properties as compared to the individual componentsw

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6
Q

what dentin made of

A

collagen matrix and hydroxyapatite crystals

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7
Q

what are dental composites made of

A

organic resin matrix and inorganic filler particles

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8
Q

what is dental composite

A

tooth colored restorative material containing an organic resin matrix phase reinforced by dispersed filler particles phase bound to the resin by a silane coupling agent and an initiatory accelerator system

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9
Q

what are the uses and applications of composites

A
  • tooth colored restorative material
  • bonding agents
  • sealants
  • composite resin luting agents
  • resin modified glass ionomer materials
  • light activated liner materials
  • CAD/CAM blocks
  • resin endodontic sealers
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10
Q

what are the packaging types of dental composite and what is the goal of them

A
  • protect against visible light and moisture
  • plastic syringes
  • unit dose capsules
  • dual paste syringes
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11
Q

what are the components of composites

A

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

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12
Q

what is in the resin matrix

A

-BisGMA
- UDMA
- TEGDMA

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13
Q

describe BisGMA and UDMA

A
  • high molecular weight monomers- diluents necessary
  • low viscosity
  • low flexibilityd
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14
Q

describe TEGDMA

A
  • high fluid monomer
  • diluent for high molecular weight monomers ~25-30% added to Bis GMA to improve consistency for manipulation
  • amount of TEGDMA = polymerization shrinkage
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15
Q

what is a property of the difunctional monomers of the resin matrix components

A

2 reactive ends to allow cross linking

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16
Q

what are the filler particles

A
  • crystalline silica
  • Ba
  • Li
    -Al silicate glass
  • amorphous silica
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17
Q

describe the filler particles

A
  • dispersed in resin matrix
  • distribution varies depending on the mateiral
  • filler loading % expressed by weight or by volume
  • filler size and combination
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18
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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19
Q

what does higher filler amount affect

A

reduces the thermal expansion and contraction coefficients

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20
Q

describe what the coupling agent does

A
  • bond between the two phases of composite
  • interfacial bridge bonds the filler to the resin matrix
  • better stress distribution between resin matrix and filler particles
  • improves the mechanical properties
  • decreased water sorption along filler- resin interface
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21
Q

what do monomers get converted into

A

polymers

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22
Q

what is the activator/initiator process triggered by

A

free radicals

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23
Q

what is the activator and initiator of chemical or self cure

A
  • activator: tertiary amine
  • initiator: benzoyl peroxide
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24
Q

what is the activator and initiator of light cured

A
  • activator: blue light- 465 nm
  • initiator: camphorquinone (photosensitizer) and DMAEMA (amine)
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25
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 resins
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26
Q

what are the polymerization inhibitors

A
  • butylated hydroxytoluene (BHT)
  • hydroquinone
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27
Q

what are the optical modifiers

A
  • pigments: metal oxides
  • opacifiers
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28
Q

what are the opacifiers

A
  • titanium and aluminum oxide
  • controls opacity or translucency
  • comes in dentin and enamel shades
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29
Q

how are composites classified

A
  • filler particle and size distribution
  • handling characteristics
  • type of polymerization
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30
Q

what are the classes of composites

A
  • macrofill
  • midifill
    -microfill
  • hybrids: midi- micro hybrid, mini-micro hybrid, mini nano hybrid
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31
Q

describe macrofill and midifill composites

A
  • not used much today
  • filler size: 10-100 um (macro) and 1-10 um (midi)
  • 65-70% wt%
  • large fillers - rough surface finish
  • not good size distribution - low wear resistance
  • prone to staining
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32
Q

what are the brands of macrofill and midifill

A

-adaptic: macro
- concise: midi

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33
Q

describe microfill composites

A

-0.01-0.1 um particles
- colloidal silica 40-60% wt%
- larger filler surface area
- difficult to increase filler fraction
- too viscous
- excellent finish
- low mechanical and hardness surface properties
- use for esthetic, low stress sites: class III, layer over hybrid

34
Q

what are the brands for Microfill

A
  • durafill VS
  • Epic TMPT
  • Renamel
  • heliomolar
35
Q

describe midi-micro hybrid

A
  • first hybrids
  • mix od midid and micro fillers
  • 75-80%wt
  • improved surface finish
  • high strength
  • universal composites: anterior and posterior
36
Q

what are the brands of midi-micro hybrid

A
  • Z250
    -Z100
  • Herculite
    -TPH
    -APH
  • Point 4
37
Q

describe mini-micro hybrid

A
  • mix of mini and micro fillers
  • 80-85% wt%
  • newer material
  • smoother finish thatn midi- micro hybrid
  • slightly lower strength
38
Q

what are the brands for mini micro hybrid

A
  • clearfil APX
  • 4 seasons
  • Miris
  • Vitalescence
  • synergy
  • Tetric
  • EsthetX
39
Q

describe mini nano hybrdi

A
  • mix of mini and nano fillers
  • ~80% wt
  • newest materials
  • strength comparable to microhybrids and finish equivalent to microfills
  • not all nanocomposites contain nanofiller, filler size reported in nm
40
Q

what are the brands of mini nano hybrid

A

-Filtek supreme ultra
- premise
- TPH3
-Simile

41
Q

what are the classifications by handling characterisitcs

A
  • regular: macrofill, microfill, hybrid, nanohybrid
  • flowable
  • bulk fill
42
Q

describe flowable composite

A
  • low viscocity and hybrid reduced filler
  • lower filler percentage 40-60%wt, decreased modulus, increased flexibility
  • adapts better without handling
  • used under conventional composite at gingival floor of class II
  • many are not radiopaque
43
Q

what is the big issue with flowable

A

difficult to distinguish from recurrent caries

44
Q

what is added to improve radiopacity in flowable

A

-barium
- strontium
- zirconium filler

45
Q

describe bulk fill composite

A
  • used to avoid incremental palcement
  • highly filled with pre polymerized particles
  • larger size fillers
  • more translucent filler particles
  • 5mm increments
  • need high output lights ~1000 mW/cm^2
46
Q

describe packable/condensable composite

A
  • packable mini and midi filler greater 80%
  • supposed to be handled like amalgam
  • conventional hybrids have superior properties
  • bulk cure inadequate
  • not well accepted: fractures at marginal ridges, changes on surface texture and color match
47
Q

what are the classifications by polymerization activation

A
  • chemical cure or self cure
  • light cure
  • dual cure
48
Q

what is the activator, initiator, advantages and disadvantages of chemical curing

A
  • activator: aromatic tertiary amine
  • initiator: benzoyl peroxide
  • advantage: bulk placement
  • disadvantage: mixing (bubbles, decreases strength), no control of working time, amine (not color stable)
49
Q

what is the activator, initiator, advantages and disadvantages of lightcuring

A
  • activator: blue light
  • initiator: camphorquinone (~470 nm) and DMAEMA (accelerator)
  • advantages: mixing not required, less porosity, increased strength. aliphatic amine (DMAEMA), more color stable than self cure aromatic tertiary amine, better control of working time
  • disadvantages: limited light penetration, less than 2mm increments for 20 sec, blue light, retina damage
50
Q

what is the free radical addition reaction of polymerization

A
  • activation: activator converts initiator into a free radical
  • initiation: free radical initiator starts the addition reaction
  • propogation: continues polymer chain growth
  • termination
51
Q

visible light is:

A

electromagnetic radiation

52
Q

what is the range of the visible light spectrum and wavelengths

A
  • red:700-750 nm to violet:390-400nm
53
Q

what is camphorquinones max absorption

A

468nm

54
Q

what is the irradiance value

A

the radiant power divided by the tip area

55
Q

higher the irradiance:

A

higher the amount of photons

56
Q

what are the procedural factors for light cure

A
  • exposure time
  • tip size: smaller tip = increase output, increase heat
  • distance: decrease output when you increase distance
57
Q

what are the clinical/restoration factors of light cure

A
  • darker shades absorb light
  • smaller particles: increase light scatter
  • curing through tooth decreases output
58
Q

what are the types of curing units

A
  • quartz- tungsten halogen (QTH)
  • plasma arc
  • laser
  • light emitting diodes (LED)
59
Q

describe QTH

A
  • source consists of tungsten filament that is surrounded by a clear, crystalline quartx bulk containing a chlorine based halogen gas
  • broad emission spectrum (~400-500nm)
  • cooling system is noisy
  • relatively low irradiance
  • heating in the output- dont touch the tip
  • retinal damage
60
Q

describe the plasma arc light (PAC)

A
  • broad emission spectrum (390-510nm)
  • high radiant power and high irradiance
  • PAC lights are expensive
  • noisy, large, not portable, cannot be battery operated
  • become less popular with the introduction of LED curing lights
61
Q

decsribe the argon ion laster

A
  • high irradiance
  • 10 seconds or less compared to 40-60 with a conventional GTH source
  • produces several intense and narrow emission peaks
  • viable option for a high irradiance curing light that could rapidly cure dental resins
  • argon- ion laters are expensive
  • become less popular with LED lights
62
Q

describe LED lights

A
  • introduced in 1990s
  • advantages: solid state, lightweight, battery driven, more efficient, extremely long working life
  • first and second generation: relatively narrow emission spectrum
  • third generation: multiwave, multipeak, polywave. ranges from 390-430nm and 440-500 nm
63
Q

what are the factors that reduce light output

A
  • degradation
  • tip contamination by resin buildup - lower output
  • sterilization problems- frosting the tip
  • infection control barriers- need longer curing times
64
Q

what are the deficient polymerization problems

A
  • marginal staining
  • increased wear
  • disadaptation
  • post op sensitivity
  • enamel microcrakcs
  • secondary caries
  • microleakage
  • bulk fracture of the restoration
  • release of chemicals
65
Q

what is the oxygen inhibited layer

A
  • ~15 microns thick, on the outer layer which facilitates addition and wetting of subsequent layers
  • just cured composite may have 50% of the unreacted methacrylate groups to co polermize with the newly added material
  • older restorations will fully cure over time, do not have the unreacted methacrylate groups
  • repair strength will be 50% of the original restoration
66
Q

describe dual cure

A
  • both light and chemical activator/ initiator systems
  • used under ceramic inlays, onlays and crowns
  • composite cement= accomodates thicker areas, light may not penetrate adequately
67
Q

what are the important properties of dental composute

A
  • polyermization srhinkage and stress
  • wear resistance
  • surface finish
  • marginal infiltration
  • water sorption
  • radiopacity
  • color stability
68
Q

what does polymerization yielding stress caused

A

stress occurs at the composite- tooth interfacr

69
Q

stress level will vary with polymerization shrinkage depending on:

A

the type of restoration configuration factor, C factorw

70
Q

what is C factor

A

bonded/ unbonded surfaces

71
Q

the higher the C factor:

A

the higher the stress

72
Q

which restoration type has highest C factor

A

class I

73
Q

what is failure at the interface caused by

A

reduced by effective bonding and lower C factor

74
Q

describe polymerization stress in self cure composite

A
  • slower polymerization rate
  • internal flow, compensates for shrinkage
75
Q

describe polymerization shrinkage in incremental placement

A
  • decreased C factor
  • shrinkage is not reduced
  • stress is reduced
76
Q

what helps decrease wear resistance

A
  • biofilm formation = bacterial acids = soften resin matrix
  • higher filler amount = higher wear resistance
77
Q

what does surface finish depend on

A
  • type and size of filler
  • smaller filler size = higher surface finish
78
Q

describe marginal infiltration

A
  • decreased with improvement of adhesive systems
  • failure gap between tooth and composite
  • secondary caries, marginal staining and fracture and post op sensitivity
79
Q

describe water sorption

A
  • lower filler amount, higher water sorption = higher expansion
  • BisGMA and TEGDMA: higher sorption as compared to UDMA
80
Q

what is radiopacity important do

A

to distinguish carious tissue and marginal adaptation, air bubbles

81
Q

when is color stability affected in composite

A
  • color change after 2-5 years
  • food, smoking, beverages
82
Q
A

Operative II (10 decks)

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