Fluoride and phosphate release from varnishes containing fluoride and Na-trimetaphosphate

Objectives: To evaluate the amount of fluoride (F) and phosphate (P) released into artificial saliva solutions from F varnishes, supplemented or not with sodium trimetaphosphate (TMP). Methods: All varnishes contained the same basic formulation, differing regarding F and TMP concentrations, as follows: G1 (placebo – F and TMP free), G2 (5% NaF), G3 (2.5% NaF), G4 (2.5% NaF/3.5% TMP), G5 (2.5% NaF/5% TMP) and G6 (2.5% NaF/10% TMP). A thin layer of varnish was applied on polyester sheets (n=8/group). Varnishes were allowed to set (24 hours) and subsequently immersed in artificial saliva (3 mL). Polyester sheets were transferred to new vials containing fresh artificial saliva solutions at 30, 60, 90, 120, 180, 240, 300, 360, 540, 720, 900, 1080 and 1440 minutes after first immersion. F and P were analyzed with the electrode and colorimetrically, respectively. Data was analyzed by ANOVA and Tukey’s test (p<0.05). Results: The total amount of F and P released was proportional to F and TMP concentration in the varnishes, respectively. F release from F-varnishes without TMP was significantly higher than the other varnishes (p<0.001). A markedly higher fluoride release was seen for G2, G3 and G4 within the first hour, decreasing exponentially afterwards. A more constant pattern of fluoride release into the solutions was seen for G5 and G6. Significantly higher amounts of phosphate were released from G6 when compared to G4 and G5 (p<0.001) mainly within the first hour. No P was released from G1, G2 and G3. Conclusion: As no inhibitory effect was seen between F and TMP on the release of F and P into artificial saliva, the results suggest that F varnishes supplemented with TMP may be effective in preventing dental caries and erosion, as both ions take part in de- and remineralization processes.