Fluoride Retention in Nocturnal Salivary Sediment After Use of a 5000 ppm F Dentifrice: A Randomized Crossover...

Fluoride (F) is an essential strategy for caries control, with fluoridated dentifrices being the most effective form of its use. Studies have shown that salivary sediment retains more F than the supernatant, contributing to its maintenance in the oral environment. This study was aimed at evaluating the bioavailability of F in salivary sediment after the use of a high-F dentifrice during the nocturnal period. In this in vivo crossover study, 10 participants used a dentifrice containing 5000 ppm F and collected saliva during diurnal and nocturnal periods. These samples were analyzed to compare F concentrations in the salivary supernatant and sediment using an ion-specific electrode. A two-way ANOVA was used for statistical analysis, considering the factors "saliva compartment" and "period," with a significance level of 5%. No significant differences were observed between the two periods at baseline (p > 0.05); however, in both periods, F levels were significantly higher in the sediment than in the supernatant (p < 0.05). Immediately after brushing, a peak in F concentration was observed in all compartments, followed by a gradual decline over time. After 2 h, F retention remained consistently higher in the sediment compared to the supernatant, especially during the nocturnal period (p < 0.05). The area under the curve (AUC) confirmed higher F bioavailability at night, with values (mean ± SD, μg F/mL.min^-1) of 3590.1 ± 450.0 for nocturnal sediment, 2598.2 ± 209.9 for diurnal sediment, 2526.7 ± 579.2 for nocturnal supernatant, and 2078.4 ± 442.8 for diurnal supernatant (p = 0.03). These findings demonstrate that bedtime brushing with a 5000-ppm F dentifrice effectively prolongs F retention in the oral environment, especially in the salivary sediment.

Brazilian Clinical Trials Registry (REBEC) identifier: RBR-10bhvcr4.