Fluoride release and recharge from bioactive resins in vitro.

Background: Bioactive resins can release fluoride ions, but their potential for fluoride recharge is unknown. This study aimed to evaluate the fluoride (F) release and recharge capacity of bioactive resins using an in vitro pH cycling model. Material and Methods: Six specimens were prepared for each group: two bioactive resins (Beautifil Flow Plus and Biocoat), a conventional resin (Opallis Flow), and a resin-modified glass ionomer cement (Ionoseal). For pH cycling, each specimen was immersed in an acidic solution (Sprite, pH 3.6) for 6 hours at 37 °C, rinsed with distilled water, and then stored in artificial saliva (pH 7.0) for 18 hours. This cycle was repeated for three consecutive days. Afterward, the samples were brushed with fluoride toothpaste and subjected to a second pH cycling phase. For F determination, 1 mL of TISAB was added to each solution, and fluoride levels were measured using an ion-selective electrode. Data were tested for normality using the Shapiro-Wilk test and analyzed by one-way ANOVA followed by Tukey's post hoc test. Results: In the initial fluoride release phase, Beautifil resin demonstrated similar performance to Ionoseal and exhibited a significantly higher fluoride release compared to the other materials (p < 0.05). However, during the recharge phase, Ionoseal demonstrated superior fluoride release compared to all other materials (p < 0.05). Conclusions: Beautifil resin and Ionoseal exhibited the highest fluoride release in both phases of pH cycling when compared to the other materials. Nevertheless, Ionoseal outperformed the others in fluoride recharge following treatment with fluoridated dentifrice. Key words:Fluorides, Bioactive Resin, Dental Materials.