FIGURE 4-3 Prevalence of severe enamel fluorosis at the person level by water fluoride concentration, permanent teeth, age < 20 years, communities outside the United States.

swered by most studies, which use Dean’s 1942 modification of his index combining “moderately severe” and “severe” classifications of his original system (Dean 1934) into a single category (Dean 1942; Rozier 1994). Three studies, however, in U.S. communities with water fluoride concentrations of approximately 4 mg/L have used enamel fluorosis indexes that draw severity distinctions within the “severe” category.

In Lowell, Indiana, with a water fluoride concentration of approximately 4 mg/L, 7% of a 1992 sample and 2% of a 1994 sample of children 7-14 years of age had at least one tooth surface assigned the highest possible TSIF score of 7 (Table 4-4). Expressed as a percentage of all tooth surfaces examined (mean, 32.3 per child), the prevalence of TSIF score 7 in the 1992 sample was substantially lower at 0.5% (Jackson et al. 1995). The lower prevalence using this metric is not surprising, as it includes surfaces on anterior teeth, which are not generally as susceptible to fluorosis as molars and other teeth located farther back in the mouth.

In Bushnell, Illinois, with a mean water fluoride concentration of 3.8 mg/L, samples of children age 8-10 years and 13-15 years were examined in 1980 and 1985 (Heifetz et al. 1988). As shown in Table 4-5, the TSIF score