Effect of amine fluoride solution with different fluoride concentrations and different pH on tooth-bound fluoride

Background and Purpose: Enamel resistance to lesion formation increases with increasing tooth-bound fluoride (F) content. The aim of this in vitro study was to examine whether the amounts of tooth-bound fluoride would be affected by reducing the fluoride concentration from 1 to 0.25% F and its pH from 5.3-4.0. Material and Methods: Surgically removed human third molars were assigned randomly into three groups. Four enamel slabs were cut from buccal or lingual surfaces of each tooth. One slab from each tooth was assigned at random to one of four subgroups. One subgroup of the slabs without treatment served as the control. The slabs of the three subgroups were shaken for three min in an amine fluoride solution with different fluoride concentrations and different pH on three successive days. Results: A statistically significant increase in tooth-bound fluoride was observed in all subgroups compared with the control subgroup. The amounts of tooth-bound fluoride produced with 1 and 0.5% F amine fluoride solution did not differ statistically (p > 0.05) and were superior to 0.25% amine fluoride solution, regardless of acidity. The amount of tooth-bound fluoride increased with the acidity at any fluoride concentrations and resulted in statistically significant increases (p < 0.05) at the highest pH in comparison with the lowest value of the pH. Conclusion: The results showed that the standard fluoride concentration in amine fluoride solution could be decreased without decreasing its ability to form tooth bound fluoride. The use of highly acidic preparations could increase fluoride content in enamel.