Non metallic restorative materials based on glass ionomer cements — recent trends and developments

In this contribution to a series of papers dealing with the colloid chemistry and structure of restorative and luting material for dentistry we will present a short introduction into the state-of-the-art of applying and developing dental material based on glass ionomer cement (GIC). The basic component of glass of GIC and related material is a glass-like calcium aluminosilicate containing some fluoride and an acidic polyelectrolyte, which is a homopolymer or copolymer of unsaturated carboxylic acids. The glass-ionomer cement sets as a result of a reaction between an acid and a base. The product of the reaction, a hydrogel salt, acts as a binding matrix surrounding the silicate particles. More recently, resin modified systems have become available commercially. These materials have dual-curing capabilities. The acid-base reaction is initiated on mixing, but proceeds slowly and thus the overall setting is accelerated by a light-activated polymerization mechanism. The major advance in the glass ionomer cement is its ability to adsorb permanently to the hydrophilic surface of tooth hard substance. The bond strength with glass ionomer cements may be enhanced by cleaning organic debris off dentin and enamel surfaces with polyacrylic acid. Another advantage of glass ionomers is constant fluoride release, which inhibits secondary caries.