CONVENTIONAL GLASS IONOMERS AS POSTERIOR RESTORATIONS - A STATUS-REPORT FOR THE AMERICAN-JOURNAL-OF-DENTISTRY

The search for a material to replace amalgam continues as a major ques t in materials science. Resin composites may offer one solution but an alternative class of material, the glass ionomer cements (GICs) may h ave some potential for fulfilling this role. GICs were first introduce d to the dental profession in 1976, and have now become an accepted pa rt of the dental armamentarium, especially for use in low load bearing situations. They possess a low coefficient of thermal expansion simil ar to that of tooth structure, physicochemical bonding to both enamel and dentin, and the release of fluoride ions into the adjacent tooth t issue. These properties help to reduce marginal leakage and may contri bute to a reduced incidence of recurrent decay in the restored tooth. Fluoride released into the ambient fluids has a caries-preventive effe ct in neighboring teeth by enhancing remineralization and inhibiting d emineralization of the dental hard tissues. The main criticisms of the GICs are their brittleness, poor surface polish, porosity and surface wear. To overcome some of these deficiencies, considerable attention has been directed at improving their physical properties, especially w ith the addition of metal powders, the metal-modified GICs. Different metal powders have been tried, including alloys of silver and tin, pur e silver, gold titanium, palladium and stainless steel. There is confl icting data as to whether or not these materials are sufficiently stro ng for use in high stress restorations, especially their potential use as replacement materials for amalgam fillings.