 2. Sample Size The sample size calculation was performed using fluoride concentration data in dental biofilm previous study and taking effect size difference between the experimental dentifrice 100 Nanoencapsulated Fluoride and positive control of at least 3.4 ppm of F- in biofilm after 12 hours, namely, 25. Admitting experimental protocol with beta error of 10 alpha error of 5, one-tailed and statistical power of 90, the sample size was calculated for 6 people. For the calculation we used the Excel software and mathematical formula for clinical trials of superiority given. Adding sample loss resulted in 12 people. 