The purpose of this study was to assess the fluoride concentration available in saliva after a professional 2% sodium fluoride solution application (9000 ppm), and to assess its duration for application to an evidence-based practice.

Two percent sodium fluoride was used among the 45 participants living in a boarding school. The participants were non-tea drinkers and non-fluoride users. The area’s water fluoride ranged from 0.34 ppm to 0.38 ppm. Whole mixed saliva samples were collected at baseline and at different time intervals after application of 2% sodium fluoride solution. Fluoride in saliva was estimated using a fluoride combination electrode (Orion models 94–09, 96–09) attached to an analyzer.

IBM SPSS Statistics version 23.0 was used for analysis. Normality of the data was assessed using the Kolmogorov – Smirnov test and box plots, and was found to be non-normal. The Wilcoxon signed-rank test was used to compare all time intervals with baseline, and statistically significant differences were observed (p = 0.0001). According to this study saliva fluoride showed a bipolar withdrawal pattern with a peak at 15 minutes and a rapid, slow decline at 60 minutes followed by a slow, persistent decline over a 20-hour period. Fluoride concentrations in saliva remained above baseline from 0.03 ppm to 0.076 ppm even after 3 months of application.