GIC revision cards Flashcards
What is the overall composition of GIC powder + liquid?
GIC is mainly composed of ion leachable glass + alumina + calcium fluoride. This is fused and ground into powder.
liquid contains acrylic acid/itaconic acid polymer, aqueous solution of maleic acid copolymer and tartaric acid in some products.
What does icatonic acid do?
Reduces viscosity of the liquid and inhibits gelation caused by intermolecular hydrogen bonding.
Tartaric acid: Improves handling characteristics, increases working time and decreases setting time.
What is the setting reaction of GIs C?
An acid base reaction. Reaction uses 2 cations in the glass (Ca and Al) which both play an important role in formation of the matrix. There are 2 distinct phases:
Dissolution: Occurs when surface of glass is attacked by polyacid resulting in limited dissolution of the glass with release of calcium, aluminium and fluoride ions. Aluminum fluoride complexes are more stable than calcium fluoride complexes and so they are formed preferentially.
Gelation: Occurs when initial set is brought about by means of cross-linking of the COO- with more mobile and readily available calcium ions to form calcium polysalts. Maturation phase is associated with progressive hydration of polysalts.
WATER ACTS AS A MEDIUM FOR THIS
What is the microstructure of GIC composed of?
Set cement is a composite of original glass particles sheathed by siliceous hydrogel and bonded by a matrix phase consisting of hydrated fluoridated calcium and aluminium polysalt
What are the properties and limitations of GIC?
Water loss and gain ruins GIC.
HIghly resistant to compressive forces but not so much flexural forces.
Solubility is higher than other cements but still very low regardless.
Biocompatibility is good; doesn’t irritate the pulp much but calcium hydroxide should still be used under.
Thermal conductivity is low like enamel.
Fluoride release is a key feature because it results ina cariostatic effect.
Aesthetics: GIC isn’t very translucent, early water contamination makes it more opaque
Adhesion is the most important property of GIC because it allows for conservative approach to be taken. It bonds well to tooth structure.
What happens to GIC if water balance is ruined?
Dessication leads to reaction retardation, shrinkage, and crazing. Must be protected by suitable barrier such as low-viscosity resin, varnish, and cocoa butter.
If hydrated results in loss of water to elution.
Both water loss and uptake result in reduction of physical properties and colour compromise.
How is susceptibility to water balance reduced in GIC?
Increasing speed of setting reaction and adding light activated resins.
What are the classifications of GIC?
Types of GIC:
Type I = Luting agents
Type II = Restoration
Type III = Liners and bases
Available as powder and liquid in different bottles, or in capsules, or as a light cure system.
