Fluoride Levels in Unstimulated Whole Saliva following Clinical Application of Different 5% NaF Varnishes

The aim of this study was to evaluate the fluoride release from differently formulated 5% NaF varnishes into unstimulated whole saliva in vivo. The fluoride concentration in unstimulated whole saliva was determined after the application of 3 different 5% NaF varnishes (5% NaF, 5% NaF + tricalcium phosphate [TCP], and 5% NaF + amorphous calcium phosphate [ACP]) or a placebo. Fifteen subjects were recruited and enrolled following Institutional Review Board approval based upon the inclusion/exclusion criteria of this study. A cross-over study design was used for the application of either one of the 5% NaF varnishes or a placebo. Unstimulated whole saliva was collected at baseline and at 1, 4, 6, 26, and 50 h following application and analyzed for supernatant ionic fluoride and whole fluoride by microdiffusion. Linear mixed-effects models (5% significance level) were used to determine the effects of varnish and time on the salivary fluoride concentration. The highest amount of fluoride in saliva was found 1 h after application of the fluoride varnishes, with no significant differences among the treatment varnishes with respect to whole fluoride but with lower levels for 5% NaF + ACP in the saliva supernatant. Salivary fluoride levels at 4, 6, and 26 h decreased at each time point and were generally significantly higher for 5% NaF and 5% NaF + TCP. After 50 h, fluoride levels in saliva for all groups were at or below baseline levels. In conclusion, the formulation of other ingredients in fluoride varnishes can affect the fluoride concentration in saliva. The reasons for this phenomenon warrant further investigation since it might affect efficacy of the treatment. This trial is registered at ClinicalTrials.gov (NCT01629290).