Glass ionomer cement is also referred to as polyalkenoate cement. It was discovered in the year 1969 by Wilson and also reported by Kent in 1971. There are basically nine types of GIC
Type 1 : Used in luting
Type 2 : Used as restoration
Type 3 : Used as liners and base
Type 4 : Used for fissures
Type 5 : Used for orthodontic purpose
Type 6 : Used as core build up material
Type 7 : Fluoride releasing GIC
Type 8 : For atraumatic restoration(ART)
Type 9 : Used for pediatric purpose
The composition of glass ionomer is unique as it has a powder liquid system
Powder composition
Aluminum fluoride
Aluminum oxide
Calcium fluoride
Sodium fluoride
Aluminum phosphate
Silicon dioxide
These components are heated around 1200 degrees and fused to form as one component "glass".
For radiopacity : zinc oxide,Barium is added,
Liquid composition
Copolymer with itaconic acid, maleic acid or tricarboxyllic acid and tartaric acid
Tartaric acid helps to increase working time and reduces the setting time.
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After the discovery of glass ionomer in early 1970's by Wilson and Kent there was a flaw in the cement they were :
1. The Glass ionomer cement took long time to set.
2. The translucency of the glass ionomer cement was also less.
So in the year 1976 it was Wilson and his co workers reported that addition of tartaric acid to the glass ionomer cement. After adding they found out that
1. Fluoride content of the glass ionomer reduced
2. It had more setting time
3. Viscosity of the cement was also reduced.
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I have provided a brief note on the indications and the contraindications for the usage of GIC.
Indications:
Restorative Materials:
Restoration of erosive/abrasive lesions without cavity preparation.
Sealing and filling of occlusal pit and fissures.
Restoration of primary teeth.
Restoration of Class V carious lesions.
Restoration of Class III carious lesions, preferably using lingual approach.
Repair of defective margins in restorations.
Minimal cavity preparations in a proximal lesions through buccal and occlusal approach (tunnel preparations).
Core built up.
Provisional restorations where future veneer crowns are contemplated.
Sealing at root surface for over dentures.
Fast Setting Lining Cements and Bases:
Lining of all types of cavities where a biological seal and cariostatic action are required.
Replacement of carious dentin for the attachment of composite resins using the acid etch technique.
Sealing and filling of occlusal tissue showing early signs of caries.
Luting Cements:
Fine grain versions of the glass Ionomer cement are now available for luting purpose because of their fluoride leach, these cements are particularly useful in patients with high caries incidence. In addition, the translucency of the glass Ionomer cement is of great value where porcelain margins are used for cosmetic reasons.
Contraindications for Use:
1) Class IV carious lesions (or) fractured incisors
2) Lesions involving large areas of labial enamel where esthetics is of major importance.
3) Class II carious lesion where conventional cavities are prepared, for replacement of existing amalgam restorations.
4) Lost cusp areas.
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