Comparative Evaluation of Salivary Fluoride Retention according to Fluoride Varnish Application Dose: Pilot Study

Background: This study aimed to compare salivary fluoride retention following different fluoride varnish (FV) application doses in vivo to determine the optimal dosage.Methods: We conducted a crossover clinical study involving nine healthy adult participants.Two doses (0.4 g and 0.2 g) of MI Varnish TM (5% sodium fluoride, 22,600 ppm fluoride; GC Corp., Tokyo, Japan) were applied intraorally.Saliva samples were collected at baseline and at 1, 4, 20, and 72 hours post-application via a distilled-water mouth-rinse method.Salivary fluoride concentrations were measured using an ion-selective electrode.Data were analyzed using the Wilcoxon signed-rank test.Statistical significance was set at p＜0.05.Results: Although salivary fluoride concentrations in the 0.4 g group were 1.53 fold and 2.16 fold higher than those in the 0.2 g group at 1 and 4 hours post-application, respectively, this difference reached statistical significance only at the 4 hour mark (p＜ 0.05).Fluoride concentrations in both groups decreased markedly by 20 hours and returned to near-baseline levels at 72 hours.No significant differences between the groups were observed at these later time points.Conclusion: Although the higher FV dose resulted in increased short-term salivary fluoride retention, no significant differences in long-term retention were observed between the two doses.These findings suggest that a reduced FV dose (0.2 g) can adequately maintain long-term fluoride retention while minimizing unnecessary fluoride exposure.