Retention of fluoride in the oral cavity: A randomized clinical study with nanoencapsulated fluoride toothpaste

To evaluate in vivo fluoride retention in saliva and dental biofilm after the use of experimental toothpaste containing nanoencapsulated fluoride (NanoF).

A triple-blind randomized clinical study involving sixty-one residents from a municipality without fluoridated drinking water. The toothpastes used in the study were: Group 1 (1100 ppm, 100% NanoF); Group 2 (1100 ppm, 50% free NaF + 50% NanoF); and Group 3 (1100 ppm, 100% free NaF). During the use of the toothpaste, samples of dental biofilm and stimulated saliva were collected. Collection times were 1 and 2 hours (h) post-brushing for biofilm, and 1, 5, 10, 15, 20, 30, 45, 60 minutes, and 2h for saliva. The fluoride [F] concentrations in saliva and dental biofilm were analyzed using a specific electrode through the hexamethyldisiloxane (HMDS) facilitated diffusion technique. The data were analyzed using the Kruskal-Wallis, Friedman, and Wilcoxon tests (p<0.05).

The values of the area under the curve (AUC) for saliva over 0-60 minutes were: G3 (97.74) > G2 (84.73) > G1 (54.98). For dental biofilm, the highest fluoride [F] concentration was observed in G1 (35.26 mg/kg), followed by G3 (34.06 mg/kg) at the 1-hour mark; at 2 hours, the results were 24.88 mg/kg and 31.43 mg/kg, respectively, with a significant reduction in [F] observed only in G1 (p=0.02).

The nanoencapsulated fluoride tested in this study exhibited a distinct pattern of fluoride release in saliva. However, in dental biofilm, the release pattern was similar to that of the free fluoride formulation (NaF).