RESUMEN
OBJECTIVES: This study aimed to evaluate the fluoride concentration in the fingernails and toenails of children aged 18-30 months during use of fluoride-containing toothpastes supplemented with calcium glycerophosphate (CaGP) or sodium trimetaphosphate (TMP). METHODS: According to the toothpaste used, children (n = 56) were randomly assigned into three groups: 500 µg F/g with 1% TMP, 500 µg F/g with 0.25% CaGP, and 1100 µg F/g. Fingernails and toenails were collected monthly over a period of 330 days, from the beginning of toothpaste use. Fluoride concentration in the water consumed by the volunteers and fluoride intake from diet and toothpaste were also determined. Fluoride analyses were performed with the electrode after hexamethyldisiloxane-facilitated diffusion or by the direct method, according to the samples. Data passed normality and homoscedasticity tests and were analyzed by 2-way analysis of variance (anova) and 1-way anova followed by Student-Newman-Keuls test (P < 0.05). RESULTS: Fluoride levels in the fingernails and toenails as well as fluoride intake from toothpaste were similar for the groups treated with 500 µg F/g with 1% TMP and 500 µg F/g with 0.25% CaGP toothpastes, but significantly lower than the 1100 µg F/g group (P < 0.05). No significant differences were noted among the groups regarding fluoride intake from diet and that by water consumed by the volunteers (P > 0.05). CONCLUSION: The results of the longitudinal study suggest that the level of fluoride present in nails was lower with the use of toothpastes with a low fluoride concentration.