Short-term Caries Study Examining the Effects of Three Doses of Sodium Fluoride Dentifrices

Objective: This well-controlled, fluoride (F) dose-response methods study was conducted in concurrence with a supervised school oral hygiene regimen to assess whether dentifrices with increasing F levels could be differentiated with small sample sizes in short time frames. Methods: The randomized, double-blind study was conducted for 21 months (mos.). Subjects (N=657, ~219 per group) were randomized to placebo, 500 ppm F or 1450 ppm F dentifrice treatments for the first 9 mos. of the study. Subjects in the placebo group were then switched to either 500 ppm or 1450 ppm F dentifrice. Subjects in the fluoride groups continued with their original treatment. A calibrated examiner measured visual-tactile caries as DMFS that was supplemented with a radiographic examination at baseline, 9 and 21 mos. Results: The mean caries increments at 9 mos. were 0.35, 0.34, and 1.28 surfaces for the 1450 ppm F, 500 ppm F, and placebo groups, respectively. The mean caries increments at 21 mos. were 0.21, 0.26, 1.75 and 1.90 surfaces for the 1450 ppm F, 500 ppm F, placebo/1450 ppm F, and placebo/500 ppm F groups, respectively. The 500 ppm and 1450 ppm F dentifrices delivered statistically significantly (p<0.05) lower DMFS scores than the placebo dentifrice at 9 mos., while at 21 mos. the 500 ppm and 1450 ppm F dentifrices delivered statistically significantly lower DMFS scores as compared to both the placebo/500 ppm F and the placebo/1450 ppm F dentifrice groups. There was no evidence of a dose response (1450 ppm F < 500 ppm F) at 9 mos. or at 21 mos. Conclusion: The effectiveness of the two F dentifrices was observed at 9 mos. These outcomes were still present at 21 mos., confirming that caries benefits can be observed in time frames as short as 9 mos. with approximately 200 subjects per treatment group.