The glass-ionomer cements (GIC), when introduced in the 1970s, were initially welcomed as the first chemically-adhesive esthetic restorative materials. However, the clinical results were disappointing, as these early products were brittle and were particularly susceptible to early water loss and uptake, and to long-term water loss. Continued development, notably the addition of resin polymerization components, has made the GIC an increasingly important part of clinical practice.