Salivary fluoride bioavailability after application of fluoride varnishes: A randomized clinical study

This study aimed to evaluate the bioavailability of F in saliva compartments (sediment and supernatant) after the use of fluoride varnishes (FV) with 5% sodium fluoride. In this randomized two-phase crossover clinical study, 15 participants were allocated into two groups and received application of Duraphat® and Fluorniz on the vestibular surface of the teeth. Unstimulated saliva was collected before the application of the FV, and 5 min, 15 min, 30 min, 1 h, 2 h, 4 h, 8 h, 12 h, 24 h, 48 h, and 96 h after application. For statistical analysis, a t-test was performed to compare the FV in the salivary compartments. The F in saliva at different times was compared with the baseline using analysis of variance, with Dunnett's post hoc test for multiple comparisons. After application, the F concentration in the salivary compartments increased (p < 0.001) and returned to baseline 24 h after application in the Duraphat® group and 8 h after application in the Fluorniz group. When comparing the salivary sediment and supernatant, there was a difference between the FV up to 48 h after application, with higher F concentrations observed in the Duraphat® group. The availability of F was higher after the use of Duraphat® (p < 0.05). The application of Duraphat® and Fluorniz increased the F concentration in saliva, and Fluorniz presented lower F bioavailability.