title: Analysis of fingernails and urine as biomarkers of fluoride exposure from dentifrice and varnish in 4- to 7-year-old children.
abstract: 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, microg) 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.
authors.affiliation: Department of Pediatric Dentistry, Orthodontics and Public Health, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: J P
authors.initials: JP
authors.lastname: Pessan
authors.forename: M L G
authors.initials: ML
authors.lastname: Pin
authors.forename: C C R
authors.initials: CC
authors.lastname: Martinhon
authors.forename: S M B
authors.initials: SM
authors.lastname: de Silva
authors.forename: J M
authors.initials: JM
authors.lastname: Granjeiro
authors.forename: M A R
authors.initials: MA
authors.lastname: Buzalaf
mesh_terms: D000704:Analysis of Variance; D015415:Biomarkers / Q000032:analysis / Q000652:urine; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003731:Dental Caries / Q000517:prevention & control; D003802:Dentifrices / Q000008:administration & dosage*; D005260:Female; D005459:Fluorides / Q000008:administration & dosage / Q000032:analysis* / Q000652:urine; D005460:Fluorides, Topical / Q000008:administration & dosage*; D006801:Humans; D008297:Male
chemical_list: D015415:Biomarkers; D003802:Dentifrices; D005460:Fluorides, Topical; D005459:Fluorides