clinical aspects of GIC Flashcards
when was GIC invented
1971
what is silicate cement
glass powder mixed with phosphoric acid to produce a hard material
what are the disadvantages of silicate
not aesthetic
low wear resistance
what was the best restorative material in 1971
gold
what is the updated version of silicate
glass powder mixed with poly carboxylic acid
benefits of updates silicate
set harder tooth coloured more wear resistant released fluoride chemically bonded to enamel and dentine
what do we call the glass ionomer
ion leachable glass
chemical elements can dissolve out
what is the 3 stages of the setting reaction
dissolution
gelation/hardening
maturation
dissolution stage 1
add water to the poly acid chain-> when you add water, H+ ions become liberated from the acid and leave this leaves negatively charged carboxyl groups on the polyacid chains
what is the glass particles made up of
silica and calcium alunimum fluoride and other make it radiopaque and tooth coloured-
what is the glass particles called
calcium alumno- fluoro- silicate glass
dissolution stage 2
when the h+ ions from the polyacid come into contact with the glass they erode the glass and release the ions into solution
dissolution stage 3
negatively charged carboxyl group on polyacid binds to calcium and aluminium
what occurs in the final stage of dissolution
cross linking of poly acid chains and the fluoride which was bound to calcium or aluminium is released off into solution
how long does it take for the paste to harden
4-5 minutes
what is the maturation phase
the ca and alundum keep forming cross links makes it even stronger
what consequence could happen in the maturation stage
the poly acids could not bind to al or ca and could free float into the saliva- leaving it weak
what can prevent polyacid floating into the saliva
coating of varnish or bonding resin
benefits of GIC
easy to use- doesnt need to bond or moisture control
chemically bonds to enamel or dentine
releases fluoride
how does gic adhere to dentine
chemical
some h+ ions come into contact with the tooth surface and that releases calcium and phosphate in the apatite and that diffuses off and the Ca and Al from GIC diffuse into the tooth
what is dentine conditioning
used to remove the smear layer of dentine
what is dentine conditioner
- by 10% polyacrylic acid leave for 20 seconds and dry
what is the % gap free margins when conditioner was not used after 100000 chewing cycles
50
what is the % gap free margins when conditioner was used after 100000 chewing cycles
90
what is a gap free margin
where the gig has stayed in good contact with the tooth surface
what happens to fluoride being released
released fast at the start but decreases and plateaus as time goes on
what percentage of GIC restorations have been removed due to secondary caries
50% of 790
what can happen to gic and fluoride toothpaste
the GIC can absorb the fluoride from toothpaste and mouthwash and then release it- this is called fluoride recharging
disadvantage of GIC
weak compared to other materials
poor aesthetics compared to composite
poor survival time
what can happen to GIC overtime
it can change colour
what is the median survival time of GIC
6.4 years
what discovery happened in 1985
silver cement
what is silver cement
amalgam powder added to GIC-
what was it thought the amalgam powder would do to the GIC
strength
and wear resistance only bought poor aesthetics
what did we find about silver cement
more resistant to acid attack
lower flexural strength
more prone to abrasion
what discover was made in 1989
resin modified GIC- added HEMA to the glass ionomer
where else is HEMA found
in the bonding agent
which light does hema polymerise under
Blue light
how can HEMA be added
as a liquid or chemically to bond with the carboxylic acid groups on some of the polyacid chains
benefits of RMGIC
BETTER aesthetics
command set
more resistant to losing ions during maturation
what happens when we go through the maturation stage in RMGIC
we shine a light on it and everything fixes into place
disadvantages of GIC
when light cured fluoride ions not released as it is fixed into place and no H+ ions released and therefore no more cross links
disadvantages of RMGIC
do not release fluoride after cured
polymerised shrinkage
not suitable for post teeth
what does the fluoride release curve look like for RMGIC
releases but then flattens and cannot be fluoride recharged
what development came along in 1990
to add smaller glass particles- occupy more of the space
examples of high density materials
fuji 9
ketac molar aplicap
issues with current GIC
weak
complicated to use- conditioning and coating
waiting time-sticky first but shortworkable time
RMGIC cease to act like GIC when cured
what is the newest development of GIC
zinc reinforcement
what happens in zinc replacement
calcium ions replaced by zinc- and zinc brings more strength
example of GIC with zinc replacement
chemfil rock
benefits of chemfil rock
better wear resistance
bonds to enamel and dentine
no conditioning
no varnish required
which patients is chemfil rock good for
children
how do we use chemfil rock
inject it
pack it
remove XS
how long can chemfil rock last
a few months maybe years
what happens in the mauration stage of chemfil
further cross liking
fluoride release
fluoride recharge
disadvantages of chemfil rock
poor aesthetics- too white not tooth coloured
what do we use for cavities which are subginigval
RMGIC- due to poor moisture control
how long for Gic can be used for
temporary restoration- so we can remove the restoration as it is not completely tooth coloured
without removing sound tissue
what colour is fuji triage
pinky orange
