Week 5 Biomaterials

Question 1

what are the ways to classify composites

Answer 1

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

Question 2

what is the history of tooth colored materials

Answer 2

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

Question 3

what is composite

Answer 3

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

Question 4

what is dental composite

Answer 4

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

Question 5

what are the uses for dental composite

Answer 5

-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

Question 6

what does dental composite packaging consider

Answer 6

protection against visible light and moisture, allows oxygen though

Question 7

what are the components of dental composite

Answer 7

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

Question 8

what makes up the resin matrix

Answer 8

-Bis GMA
-UDMA
-TEGDMA

Question 9

what are the filler particles

Answer 9

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

Question 10

what are the benefits of filler particles

Answer 10

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

Question 11

what does higher filler amount reduce

Answer 11

the thermal expansion and contraction coefficients

Question 12

reduced polymerization shrinkage is proportional to…

Answer 12

filler volume

Question 13

what does the coupling agent do

Answer 13

strongly binds the filler to the resin matrix

Question 14

what are the benefits of coupling agent

Answer 14

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

Question 15

activator + initiator = _____

Answer 15

free radicals

Question 16

composites: monomers to be converted into ____

Answer 16

polymers

Question 17

what is the process of monomers to polymers triggered by

Answer 17

free radicals

Question 18

what are the steps in reaction of polymerization

Answer 18

-activation
- initiation
-propagation
-termination

Question 19

what does the polymerization inhibitor do

Answer 19

-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

Question 20

what are examples of polymerization inhibitors

Answer 20

BHT and hydroquinone

Question 21

what are the optical modifiers

Answer 21

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

Question 22

what are the classes of filler size and dsitribution

Answer 22

-macrofill
-midfill
-microfill
-hybrids

Question 23

describe macrofill and midifill composites

Answer 23

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

Question 24

describe microfill composite

Answer 24

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

Question 25

describe hybrid composites (midi-micro)

Answer 25

-imrpoved surface finish -high strenght - universal composites

Question 26

describe hybrid composites (mini-micro)

Answer 26

-newer material - smoother finish - slightly lower strength

Question 27

what are the brands of macrofill and midifill

Answer 27

adaptic and concise

Question 28

what are the brands of microfill

Answer 28

durafill VS, epic TMPT, renamel, heliomolar

Question 29

what are the brand of midi-micro hybrid fill

Answer 29

TPH

Question 30

what are the brands of mini-micro hybrid fill

Answer 30

-EsthetX

Question 31

what are the brands of mini-nano hybrid fill

Answer 31

filtek supreme ultra

Question 32

what are the classifications by handling characteristics

Answer 32

-flowable - packable

Question 33

describe flowable composite

Answer 33

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

Question 34

when are flowable composites used

Answer 34

under conventional composite at gingival floor of class 2

Question 35

why is lack of radiopacity a problem

Answer 35

difficult to distinuguish from recurrent caries

Question 36

what is flowable composite made of

Answer 36

barium, strontium, zirconium filler

Question 37

compare flowable vs packable

Answer 37

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

Question 38

what increments do you used bulk fill in

Answer 38

5 mm

Question 39

describe bulk fill

Answer 39

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

Question 40

what are the classes of polymerization activation

Answer 40

-self-cure -light cure -dual cure

Question 41

what are the advantages and disadvantages of light cure composite

Answer 41

- 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

Question 42

what are the procedural factors for light cure variables

Answer 42

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

Question 43

what are the types of curing units

Answer 43

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

Question 44

what are the factors that reduce light output

Answer 44

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

Question 45

describe the oxygen inhibited layer

Answer 45

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

Question 46

just cured composites may have 50% of the ____

Answer 46

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

Question 47

do older restorations have unreacted methacrylate

Answer 47

no

Question 48

what are the important properties of dental composite

Answer 48

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

Question 49

what does the polymerization yield

Answer 49

shrinkage and consequently stress at the composite tooth interface

Question 50

what does stress level vary by

Answer 50

the type of restoration configuration factor, C-factor

Question 51

what is C-factor

Answer 51

bonded/unbonded surfaces

Question 52

higher c-factor, higher ____

Answer 52

stress

Question 53

what is c factor in incremental placement

Answer 53

low

Question 54

is shrinkage reduced in incremental placement

Answer 54

no stress is reduced

Question 55

what is the polymerization rate of self cure composite

Answer 55

slower

Question 56

do composites shrink towards the light in light directed polymerization

Answer 56

no

Question 57

biofilm formation =

Answer 57

bacterial acids = soften of resin matrix

Question 58

higher filler amount =

Answer 58

higher wear resistance

Question 59

what is marginal infiltration decreased with

Answer 59

improvement of adhesive systems

Question 60

where is the failure gap in marginal infiltration

Answer 60

tooth and composite

Question 61

what happens in marginal infiltration

Answer 61

secondary caries, marginal staining and fracture, post op sensitivity

Question 62

lower filler amount and higher water sorption =

Answer 62

higher expansion

Question 63

which has higher absorption BisGMA and TEGDMA or UDMA

Answer 63

BisGMA and TEGDMA

Question 64

when does color change

Answer 64

2-5 years

Question 65

what causes color change

Answer 65

food, smoking, beverages

Question 66

what are adhesive systems

Answer 66

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

Question 66

what are adhesive systems

Answer 66

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

Question 67

what does etching do

Answer 67

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

Question 68

what does bonding do

Answer 68

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

Question 69

what is the mechanism of action in chemical bonding

Answer 69

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