tooth coloured resto materials 1: resin and bonding materials

Question 1

what are the properties were looking for in a material for a chipped tooth

Answer 1

strong
durable 
aesthetic 
non toxic-safe
needs to resist forces( for posterior) depending on the location in the mouth

Question 2

what is a composite

Answer 2

a product with at least two distinct phases

Question 3

what is the purpose of composite

Answer 3

to combine two or more materials to produce one with superior properties

Question 4

what does composite contain

Answer 4

dental filler, resin matrix and an organic binder

Question 5

can composites bind by themselves

Answer 5

no they need a binding agent which helps them bind to the tooth

Question 6

what are advantages of composite

Answer 6

aesthetics 
conservation of tooth structure 
adhesion to tooth-by binding system
low thermal conductivity
alt to amalgam

Question 7

what is the MINAMATA convention

Answer 7

the UK has signed up to get rid of mercury worldwide- not only in dentistry mostly about environmental conditions

Question 8

when did the UK sign the MINAMATA convention

Answer 8

2016

Question 9

disadvantages of composite

Answer 9

technique sensitivity
polymerisation shrinkage
decreased wear resistance

Question 10

what is the disadvantage of polymerisation shrinkage

Answer 10

this can lead to gaps forming in the composite filling
bacteria can fill this
produce acid
and lead to the carious process all over again

Question 11

what acid is used to etch the tooth

Answer 11

phosphoric acid

Question 12

what % of phosphoric acid is in the etch

Answer 12

37%

Question 13

how much % of bacteria spreading reduces with rubber dam isolation

Answer 13

98.5%

Question 14

what are the two types of polymerisation

Answer 14

addition

condensation

Question 15

how do composite fillings set

Answer 15

by free radical addition polymerisation

Question 16

what are the stages of free radical addition polymerisation

Answer 16

activation
initiation
propagation
termination

Question 17

what is the activation stage

Answer 17

chemical activation which requires organic amine and organic peroxide
or light activation camphorquinone and blue light

Question 18

what is the wavelength of the blue light

Answer 18

450-490nm

Question 19

how do we measure composite polymerisation

Answer 19

FTIR spectroscopy and see the different carbon carbon double bonds

Question 20

how much do dental composites polymerise

Answer 20

50-60%

Question 21

what does poor bonding to teeth lead to

Answer 21

poor retention
staining
sensitivity
secondary caries

Question 22

what are the three materials which bind the filler particles together

Answer 22

bis-GMA
UDMA
TEGMA

Question 23

what is the importance of binding the filler particles together

Answer 23

provides workablilty

Question 24

characteristics of bis-GMA

Answer 24

extremely viscous

Question 25

why is bis-gma viscous

Answer 25

due to large benzene rings

Question 26

how is the viscosity in bis-GMA lowered

Answer 26

by adding TEGMA w

Question 27

what happens when TEGMA is added to bis-GMA

Answer 27

FREELY MOVABLE increases polymer conversion increases crosslinkage increases shrinkage

Question 28

what happens when we light cure

Answer 28

stress set up at bonding interface

Question 29

how do we reduce the shrinkage and stress

Answer 29

by adding filler- this doesn't reduce the volume

Question 30

most common filler materials

Answer 30

fine glass fibres of barium or strontium as they add radiopacity

Question 31

how much shrinkage are most materials

Answer 31

2% linear shrinkage

Question 32

how are fillers classified

Answer 32

type of material size shape

Question 33

what shape are fillers

Answer 33

irregular or spherical

Question 34

why are spherical particles easier

Answer 34

easier to incorporate into resin mix leaving less resin mix

Question 35

why do we add different size spherical fillers

Answer 35

to fill in all the gaps possible therefore reduce polymer shrinkage

Question 36

what are the typical percentages of resin and filler

Answer 36

20% resin | 80% filler

Question 37

why do we use fillers

Answer 37

we want to reduce shrinkage water sorption thermal expansion

Question 38

what do we want to increase when using fillers

Answer 38

tensile strength modulus of elasticity abrasion resistance

Question 39

what do you need to add to bind the filler to the polymer

Answer 39

coupling agent

Question 40

what are the adv of the coupling agent

Answer 40

transfers stresses

Question 41

what do we use as the coupling agent

Answer 41

organosilane

Question 42

what end does the siloxane bind to

Answer 42

hydroxyl groups on filler

Question 43

what end binds to the resin

Answer 43

methacrylate

Question 44

what does the OH groups on the filler bind to

Answer 44

siloxane on organosilane

Question 45

what are the disadvantages of organosilane

Answer 45

age quickly in the bottle | sensitive to water so breaks down in contact with water

Question 46

what are common silane agents

Answer 46

vinyl triethoxysilane | methacryloxypropyltrimethyloxysilane

Question 47

what is the strength of composite

Answer 47

170-260 MPA

Question 48

what is the tensile strength

Answer 48

30-55mpa

Question 49

what are the three types of composite

Answer 49

universal packable flowable

Question 50

what is the difference in the three types of composite

Answer 50

change is viscosity or filler type

Question 51

what are flowables

Answer 51

slightly less filler- lower viscosity

Question 52

disadvantages with flowables

Answer 52

less filler therefore more shrinkage and reduced wear

Question 53

what is the ph of phosphoric acid

Answer 53

0.2

Question 54

what does etching do

Answer 54

decalcifies part of the enamel rods

Question 55

how long does it take for decalcification to occur

Answer 55

5-8 seconds

Question 56

what type of bonding is etching

Answer 56

mechanical with only a strength of 20mpa

Question 57

what is the point of etching

Answer 57

removing surface debris produce 10-20 infold of SA increase wetting

Question 58

what is the issue with bonding to dentine

Answer 58

hard to keep dry-23% water | moist living tissue

Question 59

what is the smear layer

Answer 59

created by the mechanical cutting of dentine- essentially dentine debris of variable thickness in addition smear plugs block dentinal tubules

Question 60

what are the benefits of the smear layer

Answer 60

can protect dentine and pulp from bacteria | eliminated diffusion of dentinal fluid

Question 61

how do we achieve optimum bonding

Answer 61

leave the smear layer remove the smear layer the smear layer is modified the smear layer is partially removed or partially replaced

Question 62

how does enamel bond to dentine

Answer 62

it is essentially an exchange process involving replacement of minerals (removed by hard dental tissues) by resin monomers which when they set micro mechanically into the porosities

Question 63

what is hybridisation

Answer 63

the infiltration of resin monomers into the collagen matrix of demineralised dentine followed by polymerisation

Question 64

what are the steps for bonding to dentine

Answer 64

acid etching primer bonding adhesive

Question 65

why do we acid etch

Answer 65

improves the retention of the restoration increases the SA removes smear layer from prep allows penetration of bonding agent into dentine

Question 66

what do we need to be careful of with acid etch

Answer 66

protecting the pulp

Question 67

why do we use a primer

Answer 67

improves the wettability of the prep penetrates etched dentine tubules applied in a thin layer and air dry but don't dry too much

Question 68

why is the bonding agent important

Answer 68

unfilled or lightly filled resin adhesive bonds to collagen fibrils in dentine mechanically locks in- hybrid layer applied in a thin layer

Question 69

how long do we light cure the bond

Answer 69

40 seconds- 2x 20 second timing

Question 70

what are the characteristics of primer

Answer 70

it is amphiphilic and low viscosity

Question 71

what is added to primer

Answer 71

solvents to improve viscosity

Question 72

what are the three types of etch and rinse primers

Answer 72

acetone based ethanol based water based

Question 73

example of acetone based primer

Answer 73

all bond 2 | one step

Question 74

example of ethanol based primer

Answer 74

optibond

Question 75

example of water based primer

Answer 75

scotch bond MP | scotchbond 1

Question 76

what are the advantages of 2 step process of bonding

Answer 76

application time is lower | technique sensitivity is lower