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Flashcards in tooth coloured filling materials 2 Deck (53)
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1
Q

what are examples of cements

A

GIC
light cured glass ionomer cement
composer
composite

2
Q

what can cements be

A

hydrophilic

or hydrophobic

3
Q

describe glass polyalkenoates

A

formed as the result of a acid base reaction lion between fluoride containing glass and a poly acid- usually poly acrylic acid
they are adhesive
cariostatic

4
Q

what is the composition of glass polyalkenoates

A

fluoro-alumino-phospho-silicate glass polyacid

eg polyacrylic acid or polymaleic acid

5
Q

what are the disadvantages of poly alkenoates

A
technique sensitive 
moisture sensitive 
cannot be placed in stress bearing areas 
low tensile and fracture toughness
poor wear resistance 
average aesthetics
6
Q

what does adding a acid + base equal

A

salt + water

7
Q

what are the steps of the setting reaction

A
decomposition 
migration 
gelation 
post set hardening
maturation
8
Q

how does the glass polyalkenoate bind to the collagen fibres

A

h+ ions

9
Q

how does the glass polyalkenoate bind to the tooth surface

A

calcium ions and al3+ ions in a process called chelation

10
Q

what happens in the maturation stage

A

al3+ salts precipitate for 24 hours
the setting process can continue for unto a year but very slowly
the formation of poly salts is continued

11
Q

what happens to fluoride ions

A

not an integral part of the matrix and can be released without upsetting the structure of the cement

12
Q

what role does water play

A

slowly hydrates the mature cross linked matrix
this leads to increase strength
improved translucency
increased resistance to desiccation

13
Q

what can XS water lead to

A

CONTAMINATION

therefore increased opacity and decreased hardness

14
Q

what happens if there is less water

A

desiccation

and more cracking and grazing

15
Q

when are fluoride ions released

A

released by the acid attack from the glass

16
Q

what does fluoride help with

A

contributes to the biocompatibility of the material and also the capacity to inhibit recurrent caries

17
Q

how does fluoride release

A

a rapid initial process

then a second slower much sustained process responsible for the long term release of fluoride

18
Q

what is the advantage of fluoride

A

prevents secondary caries as it promotes remineralisation

it is also the main reason for GIC replacement

19
Q

what does plaque not thrive on

A

gic

20
Q

why does strep mutans not grow on GIC

A

due to fluoride being present

21
Q

examples of alternative cements

A

diamondcarve

diamond 90

22
Q

what is diamondcarve and diamond90 based on

A

based on glass and co polymer of
polyvinyl phosphoric acid
polyacrylic acid

23
Q

give examples vicious glass polyalkenoates

A

fuji IX, ketac Molar, Hi Dense

24
Q

describe vicious glass polyalkenoates

A

higher powder:liquid ratio
lower water content
smaller glass particles
used in ART technique

25
Q

what is the survival time on posterior teeth of amalgam

A

median survival time 11 years

26
Q

what is the survival time on posterior teeth of GIC

A

MEDIAN survival time of 6 years

27
Q

deserve resin modified GIC

A

RMGIC are glass ionomer cements with the addition of a small quantity of resin components

28
Q

what is the % of resin in set cement

A

4.5-6%

29
Q

what are the advantages of RMGIC

A
tooth coloured 
improved aesthetics 
medium fluoride release 
shorter setting
decreased moisture
improved tensile strength
30
Q

what are the advantages of RMGIC part 2

A
sets on command 
better wear characteristics 
easier to use
higher bond strength to composite 
fewer steps than composite 
can finish
31
Q

describe modifications of conventional GICS

A

less water- it is replaced by a water/HEMA(hydroxyethyl methacrylate)

32
Q

what is polyacid modified with

A

side chains that can polymerise by high curing mechanisms

33
Q

what does the polymer also contain

A

polymerisable functional groups of COO and COOH which can be cured with blue light

34
Q

what does HEMA stand for

A

hydroxyethylmethacrylate

35
Q

disadvantages of HEMA

A

irritating to the eye and known contact allergen

36
Q

how do we reduce the risk of allergic response to hema

A

minimise exposure

esp to uncured resin

37
Q

clinically what is important when handling HEMA

A

protective gloves and no touch technique

38
Q

what are the indications of RMGIC

A

cervical and root caries

base and abfraction lesions

39
Q

what are the advantages of RMGIC

A

resistant to desiccation

can be contoured immediately

40
Q

what is the composition of composites

A
bis-GMA
UDMA 
EGDMA
inorganic filler
silane coupling agent 
uv stabilisers 
inhibitors
41
Q

composition of detract

A
UDMA resin
TCB resin 
strontium fluorsilicate glass 
initiators 
stabilisers
42
Q

what are compomers made from

A

from from new monomers which contain acidic and acrylate groups

43
Q

what does the setting mechanism 1st stage include

A

light curing induces the polymerisation of the resins

44
Q

what does the setting mechanism 2nd stage include

A

after water uptake the acid base reaction takes place resulting in further cross linking of the matrix

45
Q

pros of the setting mechanism

A

excellent handling
command set
good strength

46
Q

cons of the setting mechanism

A

poor adhesion
low fluoride release
needs a bonding agent

47
Q

what is the tensile strength of Fuji IILC

A

45 MPa

48
Q

what is the tensile strength of VITREMER

A

75 MPa

49
Q

what is the tensile strength of dyract

A

95 MPa

50
Q

why do GPC restorations fail

A

due to recurrent caries

51
Q

what % of GPC restorations fail due to recurrent caries

A

50%

52
Q

describe chemfil rock

A

added zinc which makes it stronger tougher and earlier
no need to condition the cavity
no need to protect with varnish

53
Q

describe new bioactive RMGIC

A

It chemically bonds to teeth, seals against bacterial microleakage, releases more fluoride and is more bioactive than glass ionomers, and is more durable and fracture resistant than composites

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