Long-term fluoride release from a glass ionomer cement, a compomer, and from experimental resin composites.

The aqueous phase of glass ionomer cements enables fluoride ions to diffuse and to be released from the material. The matrix of resin composites is much less hydrophilic, and fluoride incorporated in the material is only released in small amounts. It was the purpose of the present work to study the influence of resin matrix formulation on the fluoride release from experimental, fluoride-containing resin composites. The resin composites were based on methacrylate monomers and the adduct of maleic anhydride and HEMA (2-hydroxyethyl methacrylate). The resin composites contained 1 w% or 5 w% of AlF3*3H2O. A glass ionomer cement and a compomer were used as controls. Five disks of each material were stored in distilled water at room temperature. By means of a fluoride sensitive electrode, the fluoride release from disk-shaped specimens was determined periodically over 3 years. The glass ionomer cement released the most fluoride (1.54 +/- 4 microg/cm2 after 1 year and 248 +/- 7 microg/cm2 after 3 years). The compomer released relatively little fluoride during the 1st year (30 +/- 1 microg/cm2) but after this time the rate of fluoride release became equal to that of the glass ionomer cement, resulting in a release of 122 +/- 8 microg/cm2 after 3 years. Regarding the resin composites, the fluoride release increased with the hydrophilicity and the acid character of the polymer matrix. The release, however, was significantly lower than that from the glass ionomer cement and the compomer and ranged from 1.2 +/- 0.07 to 42 +/- 3.9 microg/cm2 at 1 year and from 2.3 +/- 0.16 to 79 +/- 6 microg/cm2 at 3 years.