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CSA > resin based materials and fissure sealants e lec > Flashcards

resin based materials and fissure sealants e lec Flashcards

understand dental metals as an adhesive and as a protective varnish layer

1
Q

what is the ideal material to replace teeth

A

a material like itself

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2
Q

what are some metallic materials

A

amalgam

and gold

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3
Q

what are the disadvantages of amalgam or gold

A

they are not aesthetic

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4
Q

give examples of ceramic materials

A

feldspatic ceramic( dental porcelain)

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5
Q

what is the disadvantage of dental porcelain

A

have to damage natural tooth

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6
Q

example of the polymer based systems

A

resin based materials

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7
Q

how are fissure sealants activated

A

light/chemical activation

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8
Q

how are dental composites activated

A

light/chemical activation

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9
Q

how are polyacid modified resins activated

A

light/chemical activation

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10
Q

how is resin modified polyalkenoate activated

A

light/chemical activation

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11
Q

how is glass polyalkenoate activated

A

chemical activation

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12
Q

what else are glass polyalkeontes also called

A

glass ionomers

or glass ionomer cements GIC

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13
Q

what are the three phases of reacted set material

A

silica gel
polymer
ionomer glass

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14
Q

how does the setting reaction occur

A

the starting materials are poly acid and an ionomer glass- a powder and a liquid

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15
Q

what is the liquid

A

usually water

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16
Q

what is the chemical reaction

A

acid + base = salt + water

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17
Q

what are acidic polymers called

A

poly acids

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18
Q

what is it called when poly acids react with poly bases

A

poly salts

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19
Q

poly salts can be used to make

A

cohesive solid material called glass polyalkeonates cements (GPAC)

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20
Q

what are the specifics of the GPAC reaction

A

initially the acid dissolves forming a vicious aqueous liquid with the glass dispersed into it
Hydrogen ions which have dissassociate from the polyacid are available to displace cations on the surface of the glass these then migrate away with some ion species reacting with the negatively charged polymer ions( fluoride) crosslinking them to become long polymer chains or polysalts.

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21
Q

what happens to the modified glass surface

A

silica gel

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22
Q

when will the material reach full strength

A

one week

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23
Q

how long do we have to wait to polish the restoration

A

a week

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24
Q

during the period where the material is strengthening what can it cause

A

CRACKS IN the surface of the material

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25
Q

how can we stop cracks in the surface of the material

A

applying varnish or petroleum jelly

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26
Q

what does the reaction also release

A

fluoride which forms fluoroapatite crystals which is greater acid resistance

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27
Q

how was secondary caries prevented

A

by fluoride being released by poly alkeonates

28
Q

what are other schools of thought about fluorine being released from polyalkenoate

A

However, some now doubt whether there is enough fluoride release to be of statistical benefit. Other schools of thought are that the glass polyalkenoate can act as a fluorine “sponge” absorbing fluoride during treatments, say with tooth paste or mouth wash, then releasing it over a prolonged period afterwards

29
Q

what do polyalkenoates also react with

A

calcium ions on the tooth surface and therefore has a direct link with the tooth

30
Q

what is the disadvantage of polyalkenoates

A

their wear resistance is poor - do not make good materials if used alone
they are too opaque where excellent aesthetics are required eg incisal edges

31
Q

what class restorations are poly alkenoates used for

A

class III and V restorations

32
Q

what are the advantages of poly alkenoates

A

sometimes can be used on the tooth without any preparation The material can also be used a luting cement (adhesive) for fixed prosthetics.
also can be used as an intermediate under amalgam or composite

33
Q

what attempts have been used to strengthen poly alienates

A

by binding silver to the poly alkenoates which strengthens it but also castes a grey shadow
also a copolymer of polyvinylphosphonic acid and polyacrylic acid, these form an improved matrix.

34
Q

what two copolymers can strengthen the poly alkenoate glass

A

polyvinylphosphonic acid and polyacrylic acid

35
Q

what is special about the filler

A

it is inert

36
Q

why is a filler used if its not a primary ingredient in the reaction

A

because the polymers used shrink by a large margin
It reduces swelling due to water absorption, the polymers are highly crosslinked leading to the formation of voids into which water can ingress.

37
Q

what could the shrinkage of the polymer lead to

A

cracking of the teeth and also tooth/cusp failure

38
Q

if we add glass to the poly alkenoate what will happen

A

it will reduce the thermal expansion and stop fracturing the tooth in extreme cases - could reduce sensitivity due to the fact the fluid in the dentinal tubules stopped moving

39
Q

what things increase by adding fillers

A

strength
aesthetics \
youngs modulus
wear resistance

40
Q

what is the conventional filler size

A

5-10 micrometers in diameter,

41
Q

what is the size of the microfilled composite

A

0.04micrometres

42
Q

hybrid materials have around % volume of filler

A

78-85%

43
Q

what does bis-GMA mean

A

bisphenol glycidyl methacrylate

44
Q

what does UDMA mean

A

urethane dimethacrylate

45
Q

what materials are used to dental composite

A

bis-GMA and UDMA

46
Q

what does bis-GMA and UDMA commonly mixed with

A

triethyleneglycol dimethacrylate (TEGMA)

47
Q

why is bis-GMA and UDMA controversial

A

skin sensitivity and linked to carcinogenic

48
Q

why can bis-GMA and UDMA still be used in dental composites

A

they are used in small amounts and polymerised in to a highly crosslinked polymer chain which is quite different.

49
Q

what is the polymer matrix cured with

A

the blue light activation

50
Q

what is the issue if the cavity is overfilled with the polymer matrix

A

the blue light will only travel a few mm so it will lead to a soggy bottom formation in the bottom of the cavity

51
Q

what are the benefits of the blue light

A

Not only that blue light sources age and there may be a need to increase exposure at the end of the bulbs life. will build up your Dental composite restoration incrementally to avoid the problems; this will also help reduce the over all effect of shrinkage which potentially could fracture a tooth

52
Q

what are the issues with dental composites

A

hydrophobic meaning you need to dry the tooth

it doesn’t bond to teeth as well- series of bonding systems that aim to interface tooth and composite

53
Q

what do bonding agents rely on

A

a pre treatment

54
Q

what is the smear layer

A

when you cut into dentine and causes debris to spread over the surface blocking the dentinal tubules

55
Q

what is used to remove the smear layer

A

phosphoric acid

56
Q

what forms if the bonding material is successful

A

the formation of tags which can enter the dentinal tubules

57
Q

what binds the filler and the matrix

A

silaine coupling agent

58
Q

what does silaine coupling agent bind

A

the filler and the matrix

59
Q

what range is the blue light wavelength

A

420-450 nm

60
Q

what’s special about resin modified polyalkenoate

A

it has carbon carbon double bond which can be broken meaning that addition polymerisation

61
Q

what are poly acid modified resins called

A

compomers

62
Q

how does poly acid modified resins work

A

once the material is placed, small amounts of water will be absorbed from the patients saliva causing disassociation at the acid groups. This in turn starts a reaction with the glass which has been replaced with an ionomer glass thus there is a small background acid base reaction which is very much secondary.

63
Q

is there a need for a bonding system in poly acid modified resins

A

no - as no initial chemical reaction with the tooth

64
Q

what are fissure sealants

A

preventative materials

65
Q

what are fissure sealants used for

A

to protect vulnerable tissues in the occlusal surfaces from acid producing bacteria

66
Q

what age group will fissure sealants be applied to

A

paediatric patients

CSA (51 decks)

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