Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Dental Materials Science BDS2 > Composite Resin > Flashcards

Composite Resin Flashcards

1
Q

what are the applications of direct filling materials?

A

new dental caries, abrasion/erosion, failed restoration/secondary caries, trauma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the ideal properties of direct filling materials?

A

strength, rigidity, hardness, bonding to tooth, thermal properties, aesthetics, handling/viscosity, smooth surface finish, low setting shrinkage, radiopaque, anticariogenic, biocompatible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is composite resin composed of?

A

filler particles, resin, camphorquinone, low weight dimethacrylates, silane coupling agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the different types of filler particles?

A

microfine silica, quartz, borosilicate glass, lithium aluminium silicate, barium aluminium silicate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the monomers used in the resin?

A

BIS-GMA or urethane dimethacrylates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the key characteristics of a monomer?

A

difunctional molecule, undergoes free radical addition polymerisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is camphorquinone

A

photoinitiator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how is camphorquinone activated?

A

blue light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does cahmphorquinone do?

A

produces free radical molecules which initiate free radical addition polymerisation of bis-GMA leading to changes in resin properties. This causes a degree of conversion of resin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what do low weight dimethacrylates do?

A

adjust viscosity and reactivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is a silane coupling agent used for?

A

to preferentially bond to glass and also bond to resin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

where does the silane coupling agent sit?

A

around the perimeter of the filler particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

when is composite used?

A

where aesthetics are important, class 3,4,5 restorations, labial veneers, inlays and onlays, luting cements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how are composite resins classified?

A

filler type, curing method, area of use (anterior/posterior/universal), handling characteristics (syringable, flowable)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the effect of adding filler particles?

A

improved mechanical properties, lower thermal expansion, lower polymerisation shrinkage, less heat of polymerisation, improved aesthetics, some radiopaque

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the different types of composite curing?

A

self curing, UV activation, light curing (blue light)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how is self curing composite activated?

A

benzoyl peroxide and aromatic tertiary amine come together which causes free radicals to break C=C bonds causing polymerisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how is light curing composite activated?

A

camphorquinone is activated by blue light which causes free radicals to break resin C=C bonds causing polymerisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are the advantages of light curing systems?

A

extended working time, less finishing, immediate finishing, less waste, higher filler levels, less porosity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the consequence of most of the blue light being absorbed close to the surface of the composite resin?

A

composite resin nearest the surface sets the most readily and becomes hard

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the ISO 4049

A

the cure test where you cure a cylinder of composite resin then scrape away the unpolymerisation layer at the bottom and measure the length of it - depth of cure defined as half of this length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the hardness ratio?

A

another way of assessing depth of cure where hardness is assessed at various depths of the resin and each value is compared to the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is depth of cure defined as?

A

depth at which material hardness is about 80% that of the cured surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the typical depth of cure?

A

2mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what does depth of cure indicate?
increment thickness to use when building a restoration
26
what does using increments greater than 2mm result in?
under-polymerised base so poor bonding to teeth and early failure
27
what is the depth of cure of hybrid composites?
2mm
28
what is the depth of cure for bulk-fill composites?
supposedly 6mm
29
what initiator do bulk fill composites also have apart from camphorquinone?
lucerin initiator
30
why do bulk fill composites have an extra photo initiator?
as it has different optical absorption spectrum and so UV and blue light are needed to polymerise material fully
31
what are the potential problems with light curing?
light/material mismatch (overexpose), premature polymerisation from dental lights, optimistic depth of cure values, recommended setting times too short, polymerisation shrinkage
32
how do you overcome recommended setting times being too short for light curing composites?
use a light curing time >30s
33
what does polymerisation shrinkage affect?
affects bond to tooth
34
how do you overcome the polymerisation shrinkage problems with light cured composites?
use small increments and light from different angles
35
what are the safety concerns for the patient with light cured composites?
exothermic reaction (heat released exceeds that of heat needed for pulpal damage), divergent light beam, modern devices are brighter/more intense and may cause thermal trauma to patients soft tissues
36
what are the safety concerns of light cured composite for the clinical staff?
occular damage from looking at the light
37
how do you overcome the risk of occular damage from curing lights?
use safety shields or safety glasses
38
what is the compressive strength of composite?
300MPa
39
what is the rigidity of composite?
15GPa so it is rigid with high Young's modulus
40
what are the mechanical requirements for a posterior composite?
high strength, high YM, high abrasion resistance
41
what are the mechanical requirements for a deciduous composite?
strong in thin section, wear = wear of tooth, bonding and microleakage
42
describe the properties of conventional composite
strong but problems with finishing and staining due to soft resins and hard particles
43
describe the properties of microfine composites
smaller particles for smoother surface and better aesthetics for longer period but inferior mechanical properties
44
describe the properties of hybrid composites
improved filler loading and coupling agents which have improvements in mechanical properties
45
what is hardness?
material surface's resistance to scratching and resistance to indentation
46
what is abrasion
removal of surface layers when two surfaces make frictional contact
47
what does surface roughness affect?
appearance, plaque retention, sensation when in contact with tongue
48
what factors of the material affect wear?
filler material, particle size distribution, filler loading, resin formulation, coupling agent
49
what are the clinical factors affecting wear?
cavity size and design, tooth position, occlusion, placement technique, cure efficiency, finishing methods
50
what is the typical bond strength of composite to enamel and dentine?
40MPa
51
what is bond strength dependent on?
surface preparation of tissue, composite brand and test method
52
what are the aims of bonding to the tooth?
reduce microleakage, counteract polymerisation shrinkage, minimise cavity design, stress transfer to tooth
53
what is the compressive strength of enamel?
262MPa
54
what is the compressive strength of dentine?
235MPa
55
what is the thermal conductivity for composite?
low
56
what is the thermal diffusivity for composite?
low
57
what is the thermal expansion coefficient for composite?
high which is poor
58
why should thermal conductivity of composite be low?
to avoid pulpal damage from hot and cold foods/fluids
59
what is thermal diffusivity?
how readily a material transmits heat when exposed to a short transient stimulus
60
why should thermal expansion coefficient be equal to the tooth?
to reduce microleakage
61
what is the thermal expansion coefficient for enamel?
11
62
what is the thermal expansion coefficient of dentine?
8
63
what is the thermal expansion coefficient for amalgam?
22-28
64
what is the thermal expansion coefficient for composite?
25-68
65
what are the properties of aesthetics?
shade range, translucency, maintenance of properties over lifetime, resistance to staining, surface finish
66
which type of restorative material is used for high caries risk and frequent attenders?
RMGI
67
what type of restorative material is used for medium caries risk regular attenders?
compomer
68
what type of restorative material is used for low caries risk patients?
composite resin

Dental Materials Science BDS2 (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions