Glass Ionomer Cement 2 Flashcards
What are the 2 mechanisms which GIC bind to the tooth tissue?
- polyacrylic acid displaces surface phosphate and calcium an enters the hydroxyapatite structure and forming a calcium polyacrylate salt
- Intermediate layer of calcium and aluminium phosphates and polyacrylates are formed at the tooth/restoration interface
What is the bond strength like?
low, but good enough
Can the bond reform if broken?
YES, there is evidence
it is considered dynamic
Why can the material and tooth tissue rebond?
due to the polyacrylate and calcium ions being in close proximity to each other
What can improve the reliability of the bond?
preconditioning surface of the tooth by an acid conditioner
What is an example of an acid conditioner?
citric and polyacrylic acids
What does the acid conditioner do to the tooth?
primarily removes the smear layer and debris form the surface of the tooth
Between polyacrylic acid and citric acid, what one is favoured for acid conditioning?
polyacrylic acid
it is not so highly mineralised
Is the ability of GIC to seal good or bad?
pretty good - get little leakage
Does GIC dimensionally change?
little or no change
Is the bond between restoration and tooth stressed or unstressed?
unstressed
When are fluoride ion released form the glass?
during setting reaction
Where do the fluoride ions sit in the material?
within the matrix and free to migrate
What does the rate of release of fluoride ions depend on?
When are the most fluoride ions relased?
during maturation phase and slows and follow a normal diffusion pattern
How long are fluoride ions released from GIC?
YEARS
When can GIC take up fluoride ions?
if the eternal concentration is higher than that in the surface
How can you ‘recharge’ the GIC?
FLUORIDE TOOTHPASTE OR GEL
When does the GIC release the fluoride ions?
When the external fluoride conc drops aka fluoride sink
What can fluoride ion release prevent?
inhibit bacterial growth and plaque build up
When does rapid wear occur of GIC?
first 10 days then slows