Long-term effects of four extraction media on the fluoride release from four polyacid-modified composite resins (compomers) and one resin-modified glass-ionomer cement.

It was the aim of the present experiments to evaluate the fluoride leaching of four compomers and one resin-modified glass-ionomer cement (gic) into aqueous media over a 1-year period. Various extraction/equilibrium solutions were applied to simulate important intraoral parameters. Specimens of Dyract, Compoglass F, F2000, one experimental compomer, and the resin-modified gic Fuji II LC were stored for 366 days in distilled water (I), acidic medium (pH 4.2) (II), neutral medium (pH 7.0) (III), or solution III supplemented with 1.6 u/mL porcine liver esterase (IV). Equilibrium media were changed and fluoride concentration was measured every 48 h (first 30 d), thereafter each week (twice), then every 14 d (three times), and finally every 28 d up to a total period of 1 year. Data were statistically analyzed for significant differences by means of Scheffe' tests (p < 0.05). The gic and the compomers leached significantly more fluoride into the acidic solution in the initial phase compared to the other media (p < 0.05). Cumulative fluoride release from all materials (except experimental compomer) was elevated because of esterase activity (p <0.05). Measurable but low quantities of fluoride were segregated into all media during the 1-year period. But no significantly different long-term fluoride release into the various media from the investigated materials was found. The data indicate that plaque-associated organic acids or salivary hydrolases may increase initial fluoride release from resin-modified gics or compomers in the oral cavity. Because long-term fluoride release from all materials decreased to low concentrations within a 30-day period, their caries preventive effect remains questionable. Copyright 2001 John Wiley & Sons, Inc.