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Yr 2 DM > DML3 - GICs > Flashcards

DML3 - GICs Flashcards

1
Q

what are the main components in the GIC powder composition

A

▹ ion leachable/ionomer glass
▹ basic components (SiO2-Al2O3- CaF2/SrF2)
▹ other components = radiopacity, ↑ fluoride release, to provide with phosphate

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2
Q

why is the SiO2 to Al2O3 ratio important in the powder composition

A

governs reactivity

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3
Q

what happens in the ion leachable glass processing

A

▹ all components in powder composition melted at high temp
▹ rapid cool
▹ grind to powder
▹ acid wash powder - controls reactivity

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4
Q

what is in the liquid composition of GICs

A

▹ 50% Aq polyacrylic acid (PAA)
(OR copolymer of acrylic + itaconic acid, OR other COOHs)
▹ 10% Aq Tartaric acid
▹ both acids freeze dried + mixed with powder
▹ water added

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5
Q

why are carboxylic (alkenoic) acid monomers combined

A

combine monomers (cross link) to increase strength of acid

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6
Q

what are the 3 main steps of the GIC setting reaction

A

sets by acid-base reaction

  1. Dissolution stage
  2. Gelation
  3. Final maturation
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7
Q

what happens in the 1st stage of GIC setting reaction

A

Dissolution stage
▹ H+ ions from polyacid dissociate + attack the glass freeing the CATions (Ca2+ + Al3+)
▹ other ions released too (Na+, F-, silicon forms)
▹ 9Ca2+ + Al3+) - form complexes with tartaric acid + F-

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8
Q

what is the action of tartaric action in the setting process

A

▹ tartaric acid complexes are stable up to a certain pH
▹ they hold cement forming ions ( ↑ working time) until acid is partially neutralised
▹ the ions released (complexes not stable) -> sharp set ( real↑viscosity growth)

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9
Q

what happens in the 2nd stage of GIC setting reaction

A

Gelation + hardening stage
▹ set occurs by polymer chain entanglement + cross-linking (ionic bonds) of chains by: Ca2+ - initial set + Al3+ final set
▹ forms hydrated CA- + Al- polyacrylates

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10
Q

what happens in the 3rd stage of GIC setting reaction

A

final maturation
▹ ratio of bound:unbound water ↑
▹ ↑ strength, can take 24hrs
▹ thats why cement need to be protected immediately after placement

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11
Q

why is it important to maintain right water balance for GIC + why it needs protection straight after placement

A

▹ early water exposure -> dissolution of reactive components (cross link ions)
▹ dehydration -> critical water loss to continue setting reaction
cement = poor properties

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12
Q

how is adhesion/chemical bonding achieved for GIC cement

A

▹ tooth surface conditioned with PAA sol
▹ removes smear layer -> surface chemically active
▹ Chelation of Ca2+ = strong ionic bond between tooth + cement is strong ionic bond
▹ extra 2ndary bonding with amino grps
▹ continuous ion exchange between tooth + (polyaicd/GIC cement)

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13
Q

what is chelation of Ca2+ during the adhesion for GIC cement

A

Ca2+ from hydroxyapatite from tooth surface + COO- from PAA conditioner form strong ionic bond

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14
Q

how is fluoride released from GIC + why is it its main benefit

A

▹ initial ↑ release from exposed glass particles
▹ long term low F- release from deep matrix areas
▹ fluoride uptake by enamel + dentin
▹ inhibits demineralisation

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15
Q

how does GIC able to inhibit caries

A

▹ F- release + (Ca2+, Sr2+)
▹ involves continuing ion exchange cement/tooth/saliva
▹ (Ca2+, Sr2+) diffusion transfer to enamel/dentine
▹ possible remineralisation

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16
Q

what is the biocompatibility of GIC

how compatible with living tissue

A

▹ bioactive
▹ low irritant despite low pH
H+ movt constrained by polymeric anion
restricts diffusion down dentinal tubules

17
Q

what are the 7 advs of using GICs

A

▹ chemical bond to tooth
▹ long term F- release + uptake
▹ no shrinkage, exotherm or free monomer
▹ self repair by uptake of Ca2+ + PO43- from saliva to tooth surface
▹ potential to remineralise
▹ thermal expansion coefficient similar to tooth
▹ aesthetics

18
Q

what are the 2 disadvs of GIC

A

▹ weaker than composites + amalgam, even though strength ↑ with age
▹ poor wear resistance early on

19
Q

what are the main uses of GICs

A

▹ restoring anterior teeth
▹ with composite in sandwich technique
▹ tunnel restorations
▹ luting (cementing) + repair materials for crown + bridges
▹ cavity lining under amalgam/composites
▹ repair erosion lesions + fissure sealants

20
Q

how are viscosity GICs different to conventional GICs

A

▹ ↑ viscosity
▹designed for atraumatic restoratives
▹ ↑ compressive strength (similar to composites)
▹ finer particle size powder - accelerate initial setting
▹ ↑ molecular weight
▹ ↑ F- release

21
Q

what is in the powder compositions of cerments

A

▹ metal (silver) fused to GIC powder then ground
▹ OR metal powder mixed with GIC powder
▹ 5% titanium dioxide added -> improves colour

22
Q

what is the liquid composition of cermets

A

▹ 50% Aq polyacrylic acid (PAA)
(OR copolymer of acrylic + itaconic acid, OR other COOHs)
▹ 10% Aq Tartaric acid
▹ both acids freeze dried + mixed with powder
▹ water added

23
Q

what are the properties of cermet

A

▹ more abrasion resistant + ↓ brittle than conventional GICs -> cermets have added metal
▹ ↓ F- release + bond strength
▹ radiopaque
▹ difficult to handle

24
Q

when are cermets used

A

▹ aesthetics not priority (silver colour)
▹ cermet/composite laminate technique
▹ linings for amalgam restorations
▹ repair of restoratives

25
Q

what is liquid composition of RMGIC

A

▹ PAA, tartaric acid
▹ water compatible monomer (HEMA or PAA with pendant methacrylate groups)
▹ photo-initiator system
▹ some Bis-GMA/UDMA

26
Q

what is the powder composition of RMGIC

A

▹ ion leachable/ionomer glass
▹ basic components (SiO2-Al2O3- CaF2/SrF2)
▹ other components = radiopacity, ↑ fluoride release, to provide with phosphate
▹ photosensitiser

27
Q

what happens in the setting reaction of RMGICs

A

Dual setting
▹ acid-base reaction of GIC
▹ photo-initiated polymerisation of monomer

28
Q

what is the stricter of the set cement for RMGIC

A 
Similar structure to conventional GIC cement
BUT
interpenetrating network (IPN) of poly salt matrix entangled with polyHema
29
Q

what are the advs of using RMGICs

A

▹ less soluble + brittle
▹ can be polished immediately
▹ F- release similar/high than conventional GICs
▹ adhesion to tooth
▹ ↑compressive strength than normal GICs
▹ ↑ working time + command set

30
Q

what are the disadvs of using RMGICs

A

▹ addition of HEMA slows acid-base reaction
▹ depth of cure ↓ than composites -> reduced light transmission of the GIC glass
▹ polymerisation shrinkage
▹ polyHEMA = hydrogel, swell in water after curing
▹ polymerisation exotherm ↑ than composites
▹ unpolymerisaed HEMA - leach out + ↑toxicity
▹ staining
▹ not photo-cured quickly properties may be affected
▹ HEMA, BisGMA and PAA can separate in the bottle

31
Q

what is RMGIC tricure

A
  • Micro-encapsulated room temp curing system
  • Tricure: photo, room-temp, acid-base reaction
    • Intended to eliminate the need for layering in deep cavities
    • Reduces swelling
32
Q

what are RMGIC used for

A 
▹ cavity lining
▹ GIC -composite laminate technique
▹ anterior restorative
▹ restorative for deciduous teeth
▹ luting cement
33
Q

what is the powder composition of PAMC (polyacid modified composites/ compomers)

A

▹ BisGMA/UDMA + visible light cure
▹ ion-leachable fluroaluminosilicate glass filler + conventional fillers
▹ acidic monomer - bifunctional monomer with pendant COOH
▹ hydrophilic monomers added - aids water absorption + F- RELEASE

34
Q 
Component
UDMA
Acid pendant Resin
Crosslinking resin
Strontium fluorosilicate glass
CPQ/amine
Stabilisers
A 
Function
Base resin
Acidic hydrophilic matrix
Harder and tougher matrix
Filler and source of fluoride, undergoes acid-base reaction
Photoinitiator system
Extend shelf life
35
Q

how are compomers similar to normal GICs

A

fluoride release
▹ 1st setting -> photo initiation of methacrylate grps
▹ after curing, water uptake in mouth allows acid/base reaction to occur
▹ F- release over time by ↓ level compared to GIC/RMGIC

36
Q

what are the properties of compomers

A

▹good handling, adapt easily to cavity walls
▹ need dentine bonding + incremental placing
▹ shrinkage similar to composite
▹ water level uptake similar to composites BUT RATE of uptake ↑
▹ inferior mech properties compared to composites

37
Q

when are compomers be used

A 
▹ low stress situations
▹ proximal + abrasion cavities
▹ perm restoration in primary teeth
▹ longterm temporary restorations in perm teeth
▹ luting cement
38
Q

What is Giomers

A

▹ composite resin + pre-reacted glass-ionomer particles
▹ F- release
▹ used in restorative, luting cement, fissure sealant

39
Q

what is a compomer (PAMC) + briefly how it works

A

light cured polymerisation
↓ F- release post-placement
needs bonding agent + placed incrementally

Yr 2 DM (5 decks)

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