Fluoride uptake and release by composites and glass ionomers in a high caries challenge situation

To evaluate the behavior of composite resins and glass ionomer cements with regard to the uptake and release of fluoride, in a high caries challenge situation.

Standard test specimens of glass ionomer cement (Chelon Fil), a resin-modified glass ionomer (Vitremer), two polyacid-modified composite resins (VariGlass and Dyract) and a composite resin (Heliomolar), were submitted for 14 days to demineralization and remineralization cycles in order to simulate a high caries challenge, while from the eighth day onward, a fluoridated dentifrice solution was applied for 5 minutes twice a day and the daily fluoride release of those materials to the mediums was quantified and compared. Fifteen test specimens were prepared for each material, making up a total of 75.

All materials studied, except for Heliomolar from day 4 to day 7 in the demineralizing solution, were capable of releasing fluoride in measurable quantities during the whole experiment. The fluoride amounts released by Chelon Fil, Vitremer, VariGlass and Dyract were significantly higher in the demineralizing solution (ANOVA, P < 0.05) than in the remineralizing solution, during almost the entire experiment. The fluoride amounts released by Heliomolar were significantly higher in the remineralizing solution (ANOVA, P < 0.05) than in the demineralizing solution, during almost the entire experiment. All materials studied were capable of uptaking fluoride from the dentifrice solution and of later releasing it to the solution, maintaining the release relatively constant and at a higher level than that seen between days 5 and 7.