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BDS2.5 Dental Materials - operative dentistry > Compomers > Flashcards

Compomers Flashcards

1
Q

What material have been termed hybrid materials?

A

compomers and resin modified glass ionomers

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2
Q

Why are compomers and resin modified glass ionomers termed hybrid materials?

A

they have both resin and glass ionomer constituents

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3
Q

What is the sequence of compomer, glass ionomer, resin modified glass ionomer and resin composite?

A
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4
Q

Why has compomers been developed?

A

in an attempt to combine the potential advantages of fluoride release as seen with glass ionomer cements with the advantages of resin composites

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5
Q

What is the main system of compomers?

A

primarily resin system

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6
Q

What are compomers manufactured without?

A

without the addition of water

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7
Q

Instead of water, what is incorporated into compomers?

A

resin

(difunctional)

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8
Q

Are resin composites hydrophillic or phobic?

A

hydrophobic, no water in the material at all

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9
Q

How do compomers differ from resin composites?

A

put an additional difunctional resin in there

become more hydrophilic, allow the uptake of water and promote the release of fluoride ions during its lifetime

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10
Q

What is the generic name of compomers?

A

polyacid-modified resin composite

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11
Q

What are the 2 resin components of the compomer?

A

contains 2 monomeric components:

1) dimethacrylate

2) difunctional resin monomer containing both carboxyl and methacrylate groups

can bind to hydrophobic and hydrophilic

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12
Q

What is the difunctional monomer?

A

TCB resin

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13
Q

What is TCB resin?

A

cross-linking reaction

reaction product of butane tetrecarboxylic acid and (HEMA) hydroxyethylmethacrylate

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14
Q

What is the most hydrophilic resin being used?

A

HEMA

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15
Q

What are the hydrophilic monomers? (examples)

A

glycerol dimethacrylate

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16
Q

What does the difunctional resin monomer do?

A

enhances water diffusion within resin matrix

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17
Q

What is the filler/ glass ionomer?

A

fluoro-alumino-silicate glass

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18
Q

What is the filler loading volume of the filler component?

A

43% and 67%

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19
Q

What are the photo-activators and initiators?

A

camphorquinone

tertiary amine

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20
Q

How many stages are in the setting reaction?

A

2 stage process

21
Q

How is the resin part and glass ionomer part cured?

A

resin = LC

glass ionomer = chemical

22
Q

What is the primary reaction?

A

LC

free radical polymerisation reaction

23
Q

What is the secondary reaction in compomer setting?

A

occurs between the glass and the carboxylate groups of the difunctional resin

24
Q

In the secondary reaction, what is formed?

A

polysalt matrix is formed around the glass (as conventional gic)

25
Q

What aids the acid/base reaction in the stage 2?

A

by additions of small parentages of hydrophilic resin

26
Q

What does addition of hydrophilic resin allow?

A

encourage diffusion of water within the resin and fluoride out

27
Q

What is the secondary reaction?

A

acid/base

28
Q

What is the polymerisation shrinkage as a percent by volume?

A

2-3.5%

29
Q

What is needed for compomers to bind to tooth tissue?

A

an intermediate bonding system

30
Q

Why cant you get the properties of the glass ionomer which bind to tooth surface well?

A

the components are bunged up in the resin matrix formed in the first reaction

it is more similar to resin composite

31
Q

What is fluoride release dependent on?

A

secondary setting reaction

32
Q

Is fluoride release slow or fast?

A

slow and steady

33
Q

Is there an initial fluoride burst initially?

A

no

34
Q

What is the concentration of fluoride within the restoration determined by?

A

determined by the secondary reaction of glass with the pendent carboxyl groups

this in turn is determined by their proximity to the reactive glass surface

35
Q

Why is there limited ability for the reaction between the glass and carboxyl groups?

A

the resin phase of the system has already set

36
Q

What reaction allows the fluoride o be released?

A

water uptaken, hydrogen ion reacts with the glass and fluoride is released

37
Q

What permits the uptake of water?

A

addition of hydrophilic resin systems

38
Q

When has the compomer fully set?

A

when the water sorption has occurred and the secondary glass filler/carboxyl reaction has completed

39
Q

How long until saturation has occurred?

A

1 week of placement in the mouth

40
Q

What is the concern of water sorption?

A

uncontrolled reaction, may lead to excessive expansion - damage to the tooth

hydroscopic expansion

41
Q

Why is hydroscopic expansion actually a good thing?

A

primary reaction there is shrinkage, reduce the effect of polymerisation shrinkage

42
Q

What is the effect of compomers uptaking oral fluids?

A

leads to discolouration of the entire restoration

43
Q

What is the wear resistance like of compomers?

A

less wear-resistance compared to resin composites

44
Q

When would you use compomers?

A

class III cavities

class V cavities

fissure sealants (flowable form)

luting of metal-based indirect restorations and orthodontic brackets (luting form for crowns)

restoration of deciduous teeth

45
Q

Would you use compomers for cermaic crowns?

A

no, the expansion could break cermain crown

46
Q

What cavities would you not use compomers?

A

class I, II, IV

not strong enough

47
Q

Why would you not use compomers for inter-visit restoration of endodontic access cavities?

A

poor ability to seal as demonstrated with microleakage

48
Q

How is the material presented?

A

compules, light tight, moisture tight

BDS2.5 Dental Materials - operative dentistry (22 decks)

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