Analysis of Fingernails and Urine as Biomarkers of Fluoride Exposure from Dentifrice and Varnish in 4- to 7-Year-Old Children

• Published in: Caries research Vol. 39; no. 5; pp. 363 - 370
• Main Authors: Pessan, J.P., Pin, M.L.G., Martinhon, C.C.R., Silva, S.M.B., Granjeiro, J.M., Buzalaf, M.A.R.
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland S. Karger AG 01.09.2005
• Subjects: Analysis of Variance; Biomarkers - analysis; Biomarkers - urine; Case-Control Studies; Child; Child, Preschool; Dental Caries - prevention & control; Dentifrices - administration & dosage; Dentistry; Female; Fluorides - administration & dosage; Fluorides - analysis; Fluorides - urine; Fluorides, Topical - administration & dosage; Humans; Male; Original Paper; Dentifrice; Fluoride varnish; Fingernails; Fluoride toxicity; Urinary excretion
• ISSN: 0008-6568; 1421-976X
• DOI: 10.1159/000086842

The use of fingernails and urine as biomarkers of exposure to fluoride (F) from fluoridated dentifrice and varnish was evaluated in twenty 4- to 7-year-old children, who were divided into two groups: group A (9 caries-free children) and group B (11 children with past caries experience). They used a placebo dentifrice for 28 days, fluoridated dentifrice (1,570 ppm F) for the following 28 days, and placebo dentifrice for an additional 28 days, then returned to their usual dentifrices. Group B children also received 4-week applications of a varnish (2.26% F) while using the fluoridated dentifrice. Urinary collections were performed 24 h before the use of fluoridated dentifrice and 24 h (group A) or 48 h (group B) after. Fingernails were clipped every 2 weeks, for 26 weeks. Total F intake from diet and dentifrice was estimated. Fingernail F concentrations did not vary significantly throughout the study. Twenty-four-hour urinary F outputs (mean ± SD, µg) were: 414 ± 200 and 468 ± 253 for placebo and F dentifrices, respectively (group A) and 402 ±206, 691 ± 345, 492 ± 243 for placebo dentifrice, F dentifrice plus F varnish and F dentifrice, respectively (group B). The use of F dentifrice did not cause a significant increase in the urinary F output. However, when F varnish was used, a transitory increase in the urinary F output was detected (p = 0.001), returning to baseline levels in the last 24 h. Thus, F varnish is a safe method for topical F application even in children that use F dentifrice regularly. According to our protocol, urine was a suitable biomarker of exposure to F from dentifrice plus varnish, but not from dentifrice alone, while nails were not.