Fluoride release process of (resin-modified) glass-ionomer cements versus (polyacid-modified) composite resins

The fluoride release of conventional and resin-modified glass-ionomers is reviewed and compared to that of fluoride-releasing (polyacid-modified) composite resins. Each formulation displays a typical fluoride release profile. The cumulative amount of fluoride released is described by [F]c = [F]It/(t + timage) + β√t for glass ionomers whether resin-modified or not, whereas for composite resins this quantity is given by [F]c = [F]It/(t + timage) + αt. Both equations indicate that two kinetic processes are responsible for the fluoride release profiles. The kinetic parameters [F]I, timage, β and α depend on the formulation. On the basis of the exchange characteristics for fluoride, an attempt is made to explain the mechanisms responsible for these fluoride release processes.