Minimal intervention in dentistry: Glass-ionomers

Some ten years after the development of the composite resin family there was another addition to the class of adhesive restorative materials. In the mid 1960s polycarboxylate cements based upon zinc oxide combined with polyalkenoic acid were developed. These demonstrated some level of ion exchange adhesion with tooth structure but they lacked both tensile and compressive strength. Alan Wilson and his team at the London Government Chemist understood the chemistry and combined a polyalkenoic acid with a silica glass, similar to that used in the silicate cements, instead of zinc oxide and developed the glass-ionomer cements. It was a further ten years before these were fully developed as a family with unique and valuable properties for use in clinical dentistry.