Glasjonomer

Glass ionomer, or glass ionomer cement (GIC), is a dental restorative material that forms a set through an acid-base reaction between fluoroaluminosilicate glass powder and polyacrylic acid. It bonds to dentin and enamel without complex bonding agents and gradually releases fluoride, which can help inhibit secondary caries. GICs are generally radiopaque, biocompatible, and relatively tolerant of moist clinical conditions.

Development and types: GICs were introduced in the 1970s by researchers such as Wilson and Kent. Conventional GICs rely on an acid-base reaction alone, while resin-modified glass ionomer cements (RMGICs) combine the glass reaction with a light-cured resin component to improve early strength and reduce moisture sensitivity. Variants include high-viscosity formulations for atraumatic restorative treatment (ART) and newer reinforced forms, such as zirconia-reinforced GICs, designed to enhance strength.

Properties and performance: GICs release fluoride and can be recharged with fluoride sources. They bond chemically to tooth structure and have a coefficient of thermal expansion similar to dentin, which can reduce marginal gaps. Limitations include lower fracture and wear resistance compared with composite resins, and greater sensitivity to moisture during setting for conventional GICs. Esthetics are acceptable but typically not as glossy as resin-based composites; durability varies with location and occlusion.

Clinical use: Indicated for Class I–V restorations in primary teeth, temporary restorations, fissure sealing, and as luting cements for crowns and inlays. They are also used as bases or liners. Handling involves conditioning the tooth with polyacrylic acid, proper mixing, prompt placement, and protection from desiccation during initial setting.