Ingestão e excreção urinária de fluoretos através da água e do dentifrício

Abstract

There are few data on how long it takes for children to eliminate circulating fluoride (F) acquired from the daily intake of water and dentifrice and whether there is agreement between observed tooth brushing habits of young children and those reported by mothers. The present study is comprised of two manuscripts, the aims of which were: 1) to investigate the effect of the discontinuation of fluoride intake from water and dentifrice on urinary fluoride excretion; and 2) to compare observed tooth brushing habits of young children and those reported by mothers. In the first paper, a convenience sample of 11 children from Ibiá, MG, Brazil (sub-optimally fluoridated water) aged from two to four years who regularly used fluoridated dentifrice took part in the study. Twenty-four-hour urine was collected from the children at baseline (Day 0) (water + fluoridated dentifrice), after the interruption of fluoride intake from water and dentifrice (Days 1 to 28) and after fluoride intake from these sources had been re-established (Days 29 to 34). Urinary volume was measured, fluoride concentration was determined and the amount of fluoride excreted was calculated (mg F/day). The Wilcoxon test was used to compare mean urinary fluoride excretion (UFE) between days (p 0.05). In the 2nd paper, 201 mothers from Montes Claros, MG, Brazil answered a self-administered questionnaire on their childs tooth brushing habits. Each mother/children pair was then asked to perform the tooth brushing as they usually do at home. An examiner observed and documented the tooth brushing. Observed tooth brushing and that reported by mothers were compared for overall agreement using Cohens Kappa coefficient, chi-square test and Fishers exact test. The 1st study revealed that F was excreted through urine within 24 hours and remained stable over the subsequent days. Mean UFE at baseline was 0.25 mg F/day (± 0.15), dropping to a mean value of 0.14 mg F/day on Days 1 to 28 (± 0.07) (statistically significant difference, p < 0.05) and rising to 0.21 (± 0.09) on Day 32 and 0.19 (± 0.08) on Day 34 (no statistically significant difference, p > 0.05). In the 2nd study, Cohens Kappa values ranged from poor to good (0 to 0.75) when comparing mothers reports and observed tooth brushing (statistically significant difference between methods, p < 0.05). The findings suggest that circulating F in the body of young children stemming from water and dentifrice intake is eliminated within a few hours after the discontinuation of the exposure. The low agreement between observed tooth brushing and the mothers reports suggests that questionnaires should be considered with caution in epidemiological surveys on fluoridated dentifrice use and the risk of dental fluorosis.