CSA clinical aspects of GIC Flashcards
What is traditional glass ionomer cement?
powder Calcium-Fluoro-Alumino-Silicate Glass and Poly Alkenoic acid.
What is most common polyalkenoic acid?
polyacrylic acid , as well as polymaleic and polyitaconic acid
What are all polyalkenoic acids?
Long hydrocarbon chain backbone
What does Glass contain?
calcium fluoride and aluminium fluoride can be displaced in acid
What is the setting reaction?
- water added to powdered glass and poly acid, paste is created
- takes several hours to reach its final strength.
What are 3 phases to setting reaction?
dissolution
gelation
hardening
What is dissolution ?
H20 added to dry components, H+ liberated from COOH groups on polyacid chains
What happens when H+ ions in dissolution come into contact with glass particles?
attack glass causing Ca, Al, F, ions to be released from glass and go into solution
What is process of gelation?
- Ca2+/Al3+ attracted to negatively charged carboxyl groups on acid chains.
- causes chains to link together.
What is process of hardening?
up to a week before material reaches final hardness and several months before full maturation.
Why must traditional GIC protected by layer of varnish for first week?
materials prone to lose ions not yet reacted with acid chains if restoration gets too wet –ions leak out into saliva and material never reach a good strength.
What are fluoride ions from CaF and AlF remain as?
unreacted and move through material into surrounding tooth
What does unreacted Fluoride impart?
anticariogenic effect on enamel and dentine adjacent to GIC
What is fluoride recharge?
New fluoride enter GIC from toothpaste and topical fluoride application
Is amount of fluoride release from GIC enough ?
doesn’t prevent caries in high risk or reverese deep carious lesions after formed
How do GIC bond to teeth?
adhere directly to enamel and dentine without need for a bonding agent.
Do gic bond stronger to enamel or dentine?
ENAMEL since more min. content here
What is freshly cut tooth surface covered by ?
smear layer- loosely bound debris GIC would bond weakly,
How to remove smear layer?
using polyacrylic acid prior to placement of the GIC.
What does polyacrylic acid do?
doesn’t etch dentine leaving exposed collagen fibres, removes smear leaving a clean dentine surface.
Are GIC water based?
tolerate wet enviro. compared to composites
Why is GIC used for subginigival restorations?
tolerate wetter enivro. but can’t bond to a tooth wet with saliva or blood
What does tradiotional glass ionomer not have?
translucency, surface polish or good shade match so use composites
Where is GIC used
Anteriorly
What are the advantages of traditional GIC?
- chemical adhesion to tooth,
- ability to bond where moisture control for composite cannot be achieved
- release of fluoride.
What are main disadvantages of GIC?
- aesthetics being not as good
- strength not as good as composite or amalgam
What was the 1985 silver cermet?
addition of amalgam powder (AG3SN) to GIC before mixing it.
What was the RESIN MODIFIED GIC?
HEMA to GIC, or grafting polymerisable groups to the poly acid chains,
Advantages of RMGIC?
- stronger, sets on command (light curing) and more resistant to losing Al and Ca ions during hardening .
- improved aesthetics and translucency.
What does resin mattrix formed not allow?
much ion movement so no varnish protection no ions can be lost.
What is biggest disadvantage of RMGIC?
fluoride ions cannot move so freely either,
Cna GIC set chemically in absecnce of light?
yes
Can RMGIC be light cured?
yes would speed up but eventually fully set chemically, so used for bonding amalgam which not allow light reach material.
What is the 2012 zinc reinforcement ?
substitution of Ca ions with Zinc ions.
- resulting material is stronger, more wear resistant and higher fracture toughness than all other types of GIC
What do 50% of GIC fail?
secondary caries
When is GIC used in cavities when no other material usable ?
patients with limited opening, difficult access, not able to properly dry, quick fix when patient is anxious.
What is life expectancy of GIC like compared to amalgam and composite ?
SHORTER
Cavity prep for GIC?
REMOVE smear layer
- brush 10% polyacrylic acid to surfaces of cavity for 10 seconds, rinse well and drying for 10 seconds.
What should cavity be like for gic since it doesnt flow well?
smooth surfaced cavity with slow speed bur
DO NOT BEVEL
How does capsule come with GIC?
correct amounts of powder and water
How is GIC placed?
directly using matrix strip or band to prevent overhangs interproximally
why not to use metal matrix band with GIC
can adhere firmly to metal and pulled out cavity when band removed.
Why do we need to work quick with GIC?
SETTING STARTS AFTER MIXING
how do we need to feel if material is sluggish?
don’t use instruments as fractures within material and pulling away from cavity walls.
What do we coat gic with?
resin bond (Optibond solo is fine) and light cure.
What is prep for RMGIC?
shape as you would for composite.
- Delay light curing
- restoration can be finished and polished immediately after
- No moisture protection is required.
What are clinical indications for traditional GIC?
• Cavities extending below the CEJ • Temporisation (DURING) Endodontics • Caries Management • Stepwise excavation • Paediatric restorations • Luting Cement for crowns - Fissure sealant
What are clinical indications for RMGIC?
• Cavities extending below the CEJ
-• Lining / Bonded amalgam
Why should RMGIC not be used for dentine bonded crowns or cementing posts?
expansion during setting that could fracture restoration or tooth
