Fluoride release uptake of polyacid-modified resin composites (compomers) in neutral and acidic buffer solutions

The aim of the present study was to evaluate the fluoride uptake/release of polyacid-modified resin composites (compomers) in neutral and acidic buffe r solutions; Two compomers (Dyract(R) and Compoglass(R)) were tested-and th e conventional glass-ionomer cement (GIC) Vivaglass Base(R) served as a con trol. Forty specimens were fabricated from each of the respective materials . Twenty of these specimens were placed in;artificial saliva and the other 20 specimens in a fluoridated dentifrice slurry for 5 min. Then, 10 fluorid ated and 10 non-fluoridated specimens were immersed ina neutral buffer solu tion (pH 6.8), and the other specimens were immersed in an acidic solution (pH 4.0). After 1, 2, 3, 4, and 5 days the samples were again placed in eit her a fluoridated dentifrice slurry or saliva for 5 min, after which time t hey were transferred to fresh buffer solutions. The fluoride content of the solutions was assessed with a fluoride sensitive electrode. Fluoride relea se from all the materials decreased continuously during the experiment, wit h a significantly higher release in the acidic solution compared to the neu tral buffer solution. Fluoridation did not result in an increased fluoride release for the compomers. However, the conventional GIC revealed a signifi cantly higher fluoride release after: fluoridation. It is concluded that Dy ract(R) and Compoglass(R) can not be replenished with fluoride; irrespectiv e of the pH value of the environment.