Influence of Dentifrice Fluoride Concentrations and pH on Toenails Fluoride

Objective: This study evaluated the influence of dentifrice pH and fluoride concentration ([F]) on toenails [F].

Method: One hundred and sixty-one 3-year-old children living in a fluoridated community were randomly allocated into 3 groups, according to the type of dentifrice they had been using for the last six months: A, liquid dentifrice (LD), 550 ppmF (n=53), pH 4.5; B, LD, 550 ppmF, pH 7.0 (n=58); C, LD, 1,100 ppmF, pH 7.0 (n=50). The parents were instructed to let the children’s toenails grow for 15 days before clipping. Samples were collected from big toenails and this procedure was repeated after 15 days. Thus, 2 samples from toenails for each child were collected. Nails [F] were analyzed with the electrode, after HMDS-facilitated diffusion. Nails data were tested by ANOVA (p<0.05).

Result: Mean (±se) toenail fluoride concentrations found for the children using the dentifrices containing 550 ppm F were similar (1.80 ± 0.13 and 1.72 ± 0.09 µg/g for the acidic and neutral dentifrices, respectively) and significantly lower than those observed for the children using the 1100 ppm F neutral dentifrice (2.57 ± 0.19 µg/g) (p<0.01).

Conclusion: According to the present protocol, the reduction of the dentifrice pH does not seem to affect F bioavailability. On the other hand, dentifrices with 550 ppm F led to significantly lower toenails [F], indicating that if there is concern with the occurrence of dental fluorosis they might be a good option for young children.