Polyacrylic cements in dentistry.

The polyacrylic cements were first introduced to dentistry in the middle 1960's when Smith showed the value of the polyacids, in developing adhesion to enamel and dentine. Within 10 years, Wilson had advanced the concept by changing the powder from a zinc oxide to glass and at the same time varying the poly-acid used. Both cements depend on the development of complex polyacrylate chains which can be linked with metal ions and in turn can form dynamic linkages with both enamel and dentine. The original polycarboxylate cement has many desirable characteristics and is still a useful cement for luting crowns and bridges and for lining cavities. However it is no longer widely used because it has been somewhat overshadowed by the glass ionomer cements which are even more versatile and have superior physical properties. By varying the type of glass, the fluoride content of the glass and the powder/liquid ratio as well as adding inclusions of other metals such as silver they can fulfil a variety of roles in restorative dentistry. However, as with any restorative material, it is essential that the operator fully understand the requirements for successful placement. The basic rules are reviewed for each of the types currently available and the steps for clinical success are detailed.