Nocturnal Salivary Fluoride Bioavailability After Brushing with a High-fluoride Dentifrice

The use of fluoridated dentifrices is recognized as the main reason for the decline of dental caries and its effect is associated with the bioavailability of fluoride (F) in the oral cavity. High-fluoride dentifrice has been indicated for patients at high risk of caries and management of root lesions. This study aimed to evaluate the bioavailability of F in saliva after the use of high-fluoride dentifrice during the nocturnal period. Fifteen healthy adults participated in this is in vivo and crossover study in which the concentration of F in their saliva was determined after brushing with the tested dentifrices: a conventional (1450 ppm F) or with high-fluoride concentration (5000 ppm F). Before brushing, the participants collected the non-stimulated saliva (baseline), immediately after brushing (time zero) and after 5min, 2h, 4h, and 8h, during the nocturnal period (between 10:00 pm and 06:00 am). The salivary F concentration was determined using a specific F ion electrode. Regarding statistical analysis, a paired t-test was used to compare dentifrices with p fixed at 5%. At baseline, there was no significant difference between groups (p>0.001). Immediately after brushing, both dentifrices increased the F salivary concentration, with the highest concentration reached in time zero; however, the use of 5000 ppm F dentifrice maintained the higher F salivary concentration at all times evaluated (p<0.001), remaining higher until 8 h after brushing. Furthermore, this treatment showed higher F bioavailability in relation to time, evaluated by the area under the curve (p<0.001). Thus, it can be concluded that the high-fluoride dentifrice increased the bioavailability of salivary F during the nocturnal period in comparison with conventional dentifrice.