Lower Fluoride-, Calcium- and Phosphate-containing Rinse More Effectively Enhances Fluoride Uptake in Plaque than NaF Rinse

Objective: To evaluate the effects of a remineralisation solution (RS) containing lower fluoride (F), calcium (Ca) and phosphate (P) in comparison with conventional NaF rinse on F and Ca uptake by dental plaque, and on acid resistance and remineralisation of enamel. Methods: Eight subjects participated in this randomised, double-blind and cross-over in vivo study. Subjects wore removable appliances mounted with a pair of enamel blocks and applied the RS rinse and conventional NaF rinse three times per day for 1 week, repectively. The RS rinse, pH 6.5, contained 0.53 mmol/L F of NaF, 15 mmol/L CaCl2, and 9 mmol/L NaH2PO4. The NaF rinse contained 12 mmol/L F. Dental plaque was accumulated for 48 h and collected after fasting overnight after the last use of the rinse. After acid extraction, F and Ca in the plaque were measured by an ion-selective electrode and atomic absorption spectroscopy, respectively. Acid resistance of the enamel was evaluated by microradiography after the enamel blocks were artificially demineralised by acid gel in vitro. The remineralisation of the pre-softened enamel was determined using a microhardness test. Results: Both rinses significantly enhanced F and Ca uptake in whole plaque. RS rinse produced a similar F deposition in plaque to the NaF rinse, although the formulation of RS rinse contained 22.6 times less F than the NaF rinse did. Moreover, RS rinse more effectively enhanced acid resistance and remineralisation of enamel than the NaF rinse did. Conclusion: RS rinse can provide greater cariostatic effects with a lower F dosage than the conventional NaF rinse, with less worry about excessive systemic F intake in children. Keywords: fluoride, dental plaque, mouth rinse, acid resistance, remineralisation