Salivary fluoride levels following application of fluoride varnish or fluoride rinse.

Objectives: This study examined the concentration of fluoride in whole saliva over time following the application of a fluoride varnish or a single rinse with a fluoride solution.
Methods: A two-period, two-treatment randomized cross-over experimental trial with a 2-week washout period was used with 16 adult subjects. In the first period, eight subjects rinsed once with a 0.05% NaF solution and 8 subjects had 5.0% NaF varnish applied to facial and lingual surfaces of 20 teeth. Stimulated whole saliva was collected at baseline, 5 and 15 min, 1, 2, 4, 8, 12, 24, 32, 48, 56, 72, 80, 96, 104 h. After the washout period each subject was switched to the other treatment and saliva was collected at the same intervals. Salivary fluoride content was measured with the micro-diffusion method.
Results: The NaF levels peaked at 5 min after application for both varnish (mean +/- SE 24.5 +/- 5.0 ppm) and rinse (3.2 +/- 0.8 ppm). Mean NaF levels returned to baseline, on average, within 2 h for the rinse and within 24 h for the varnish. The maximum fluoride levels were significantly greater (P < 0.01) with the varnish than with the rinse and remained above baseline levels for a longer duration.
Conclusions: Salivary fluoride levels with the rinse returned to baseline, on average, in 2 h while they remained elevated for, on average, 24 h with the varnish. Salivary fluoride levels from the varnish were found to be comparable with those in previous studies for 1.1% neutral NaF.