the percentage of decayed and filled surfaces was 21 percent lower in the fluoridated community. Multiple regression analysis indicated that this difference was due to the community of residence but not to differences in past dental treatment, frequency of toothbrushing with a fluoridated toothpaste, or the frequency of drinking tea.

Bone Mineral Content

Several reports published 30 to 40 years ago suggested that the long-term ingestion of fluoride at levels slightly above optimum for caries prevention improved the quality of the human skeleton and that the risk of osteoporosis might thereby be reduced (Bernstein et al., 1966; Leone et al., 1955, 1960). A recent Finnish study concluded that, compared with the low-fluoride control group, vertebral bone mineral density (BMD) was increased slightly while femoral neck BMD was not affected among perimenopausal women who had used fluoridated water (1.0 to 1.2 mg/liter) for 10 years or more (Kröger et al., 1994). There was no difference between the groups in the prevalence of self-reported bone fractures. Richards et al. (1994) reported that the normal, age-related increase in bone fluoride concentrations (range 463 to 4,000 mg/kg) had no effect on the compressive strength or ash density of vertebra in Danish men and women whose ages ranged from 20 to 91 years. Sowers et al. (1986, 1991), however, reported a marginal increase in bone fractures (self-reported) and lower bone densities among women whose drinking water contained 4 mg/liter of fluoride.

Some evidence exists that fluoride may inhibit the calcification of soft tissues (Taves and Neuman, 1964; Zipkin et al., 1970), including the aorta (Bernstein et al., 1966). Taves (1978) reported that the standardized mortality rate due to ischemic heart disease in cities with optimally fluoridated water was lower than in cities with low water fluoride concentrations. Data are insufficient to justify using these effects as the basis for estimating an AI for fluoride.

Fluoride Balance

As shown in studies with infants (Ekstrand et al., 1984, 1994a, b) and adults (Largent, 1952; Maheshwari et al., 1981), the balance of fluoride can be negative. This occurs when chronic intake is reduced sufficiently to allow plasma fluoride concentrations to fall, which promotes the mobilization of the ion from calcified tissues. However, no data document the effects of a long-term negative fluoride balance on enamel, on salivary or plaque concentrations, or on



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