CHEMISTRY OF GLASS-IONOMER CEMENTS - A REVIEW

Studies of the setting of glass-ionomer cements have been carried out for over twenty years, and there is now a considerable body of informa tion concerning the steps that lead to the conversion of a freshly mix ed cement paste into a solid, durable dental restorative. This paper r eviews these studies, paying particular attention to more recent work. The conclusion is that glass-ionomers consist of interpenetrating net works of inorganic and organic components forming a matrix in which pa rticles of unreacted glass are embedded. However, there remain uncerta inties over aspects of the setting chemistry, for example over the rol e of (+)-tartaric acid in the setting reaction, and over the nature of the fluoride species which form during the reaction. The chemistry of resin-modified glass-ionomers is also discussed and shown to be more complex than that of the simple cements. The presence of the resin com ponent slows down the ionic cure reaction of the conventional cement, and leads to both a significant exotherm and a set material capable of absorbing water reversibly. The paper concludes that the microstructu re of the set cement depends completely on chemical composition and th e kinetics of the setting process, and that an understanding of the se tting chemistry of these materials is thus important for optimal clini cal use. (C) 1998 Published by Elsevier Science Ltd. All rights reserv ed.