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The purpose of this case-control investigation was to investigate the possible association between mild-to-moderate enamel fluorosis and exposure during early childhood to infant formula, fluoride toothpaste, and/or fluoride supplements. Analysis was performed on 401 residents of fluoridated communities in Connecticut, who were 12-16 years old and born prior to 1980. The case and control subjects for this study were selected on the basis of a clinical examination given in 1991. Subject fluorosis status was determined using the Fluorosis Risk Index. Risk factor exposure was ascertained via a mailed questionnaire with a response rate of 89% and a questionnaire reliability of 87%. Logistic regression analyses, which adjusted for confounding variables, revealed that mild-to-moderate enamel fluorosis on early forming (Fluorosis Risk Index (FRI) classification I) enamel surfaces was strongly associated with both milk-based (odds ratio (OR) = 3.34, 95% confidence interval (CI) 1.38-8.07) and soy-based (OR = 7.16, 95% CI 1.35-37.89) infant formula use, as well as with frequent brushing (OR = 2.80, 95% CI 1.15-6.81). A very strong association was observed with inappropriate fluoride supplement use (OR = 23.74, 95% CI 3.43-164.30). Respectively similar associations were observed between mild-to-moderate enamel fluorosis on later forming (FRI classification II) enamel surfaces and frequent brushing and fluoride supplement use, but not with infant formula use.

This case-control study investigated risk factors for enamel fluorosis in optimally fluoridated children, born after the US infant formula industry voluntarily reduced the fluoride content of their products. Analysis was performed on 233 children, aged 10-14 years. Case-control status was determined using the Fluorosis Risk Index (FRI). Risk factor exposure was ascertained via a mailed questionnaire. Logistic regression analyses revealed a strong association between mild-to-moderate enamel fluorosis on early forming (FRI classification I) enamel surfaces and both fluoride supplement use (odds ratio (OR)=5.95, 95% confidence interval (CI) 1.06-33.53), and early fluoride toothpaste use (OR=6.35, 95% CI 1.21-33.40). The authors found a suggestive, but nonsignificant, association between fluorosis on these enamel surfaces and infant formula in the form of powdered concentrate (OR=4.33, 95% CI 0.73-25.66). There was a strong association between mild-to-moderate fluorosis on later forming (FRI classification II) enamel surfaces and infant formula use in the form of powdered concentrate (OR=10.77, 95% CI 1.89-61.25), fluoride supplement use (OR=10.83, 95% CI 1.90-61.55), and early fluoride toothpaste use (OR=8.37, 95% CI 1.68-41.72). No association was observed between the use of ready to feed infant formula and enamel fluorosis.

Eight hundred fifty 11- to 14-year-old residents of nonfluoridated communities in Massachusetts and Connecticut, who were born between 1972 and 1975, were investigated in a case-control study of the possible association between enamel fluorosis and exposure to fluoride supplements, infant formula, and/or fluoride dentifrice. The effect of median household income, an indicator of socioeconomic status, was also examined. Clinical examination, using the Fluorosis Risk Index, a fluorosis index developed for this project, allowed cases and controls to be identified based upon the specific time period of exposure to the various sources of ingested fluoride. Risk factor exposure was assessed via a mailed questionnaire with a response rate of 80%. Mild-to-moderate enamel fluorosis was strongly associated with fluoride supplementation during the first six years of life (odds ratio = 4.0) and with median household income (odds ratio = 6.6). Subjects in the middle median household income group who had used fluoride supplements through the first six years of life had a 28-fold increase in the risk of fluorosis compared with unexposed subjects in the lower median household income group. An odds ratio of 1.7 associated with infant formula use was suggestive of an increased risk of enamel fluorosis as was an odds ratio of 2.9 associated with fluoride dentifrice use.