A tooth-coloured material used in the restoration of teeth.
GICs were first developed in the early 1970s by Wilson and Kent. It is the product of an acid-base reaction between basic fluoroaluminosilicate glass powder and polycarboxylic acid in the presence of water.
fluoroaluminosilicate glass (base) + polyacid (acid) --> polyacid matrix (salts)
It is an adhesive restoration, in that it adheres to tooth structure via ionic exchange. Only limited conditioning of the cavity is required with 10% polyacrylic acid if necessary. No etching or bonding required. It exhibits good biocompatibility with the surrounding tissues.
The structure of the material is such that is releases fluoride that can be taken up by the enamel and dentine cavity walls. Anticariogenic potential! That is, the potential to inhibit caries (decay). Its fluoride store is also rechargeable each time it comes into contact with fluoride e.g. in toothpaste.
The encapsulated form of the materials is easy to dispense and a God-send in pediatric restorations.
Colour matching is good, but it does not reach the aesthetic polished finish of composite restorations.
It has inferior mechanical properties to composite resins, in terms of bending strength, tensile strength, wear resistance and fracture toughness. See resin-modified glass ionomer cement.
The acid-base setting reaction is sensitive to moisture contamination, and extra care must be taken to protect the material from getting wet when initially placed. This implies the use of a varnish or a low viscosity bonding resin to seal it from the oral environment.
Clinical applications
- Restorative material - as a filling material
- Luting agent - used to cement crowns and bridges
- Liner/Base - to line the base of a cavity for extra protection or bonding
- Root canal sealing - as the sealing cement in root canal fillings
- Orthodontic band and bracket bonding - to stick those metal bits to your teeth
- Fissure sealing - as a fissure sealant material