Validation of Fingernail Fluoride Concentration as a Predictor of Risk for Dental Fluorosis

Abstract

The aim of this study was to validate the use of fingernail fluoride concentrations at ages 2–7 years as predictors of the risk for developing dental fluorosis in the permanent dentition. Fifty-six children of both genders (10–15 years of age) had their incisors and premolars examined for dental fluorosis using the Thylstrup-Fejerskov index. Fingernail fluoride concentrations were obtained from previous studies when children were 2–7 years of age. Data were analyzed by unpaired t test, ANOVA, and Fisher’s exact test when the fingernail fluoride concentrations were dichotomized (≤2 or >2 µg/g). Children with dental fluorosis had significantly higher fingernail fluoride concentrations than those without the condition, and the concentrations tended to increase with the severity of fluorosis (r² = 0.47, p < 0.0001). Using a fingernail fluoride concentration of 2 µg/g at ages 2–7 years as a threshold, this biomarker had high sensitivity (0.84) and moderate specificity (0.53) as a predictor for dental fluorosis. The high positive predictive value indicates that fingernail fluoride concentrations should be useful in public health research, since it has the potential to identify around 80% of children at risk of developing dental fluorosis.

Longitudinal evaluation of fluoride levels in nails of 18–30‐month‐old children that were using toothpastes with 500 and 1100 μg F/g

“…Because we found no difference among groups, the statistical difference found in the fluoride concentration in nails can be attributed to the toothpastes that were used. Moreover, the water consumed showed lower mean fluoride concentrations than those found in other studies . The low fluoride concentration found in diet can be partially explained by its low concentration in water; volunteers consumed more mineral water (72%) with low fluoride concentrations.…”

“…Currently, nails are one of the most studied biomarkers of fluoride exposure. . Because there is a trend toward the use of low‐fluoride‐concentration toothpastes for children during the critical period of fluorosis development , in this longitudinal study, we evaluated the fluoride concentration in the nails of children considered at risk for fluorosis when 1100 μg F/g, 500 μg F/g with TMP, or 500 μg F/g with CaGP toothpastes were used.…”

“…In the literature, fingernails have shown higher fluoride concentrations than toenails, which can be attributed to a lower exposure of toenails to external contamination . A recent study evaluated the use of fingernail fluoride concentration at ages 2–7 years as a predictor of the risk for developing dental fluorosis in the permanent dentition, and they observed that fingernail fluoride concentrations could be useful in public health research because it has the potential to identify ~80% of children at risk of developing dental fluorosis.…”

U.S. Public Health Service Recommendation for Fluoride Concentration in Drinking Water for the Prevention of Dental Caries

“…A recent study documented the validity of fingernail fluoride concentrations at age 2-7 years as a biomarker for dental fluorosis of the permanent teeth at age 10-15 years. 95 …”

Fluoride intake from fluids and urinary fluoride excretion by young children in Kuwait: a non‐fluoridated community

“…Urinary fluoride excretion among the children was low, being well below the provisional standards for urinary fluoride excretion of 360-480 lg/ day for optimal fluoride usage by 3-5-year-olds (41). Measurement of fluoride level in toe/fingernails may be an alternative approach to assessing fluoride ingestion (42), as it has recently been shown that finger nail fluoride levels lower than 2 ppm are associated with reduced risk of fluorosis (43). Furthermore, the fluoride/creatinine ratio of 0.49-0.60 obtained in the present study was much below values obtained in optimally or near optimally fluoridated communities in different parts of the world: 1.49 reported by Zohouri et al (26) in the United Kingdom for children aged 1-3 years, 1.51 by Kertesz et al (33) for 8-13-year-olds in Hungary, and 1 by Szekely (44) for children aged 3-7 years in Romania.…”