Study of effect on teeth of intermittent fluoridation of a community water supply.

THE city of Pulaski in Giles County, Tenn., affords an area in which the intermittent fluoridation of water can be studied. The effect on the teeth of children of intermittent fluoridation of a municipal water supply has not been reported. The Pulaski water supply is derived from Richland Creek, while the surrounding area is served by ground water. The intermittent fluoridation of the water supply of Pulaski possibly is related to the water saturation in the ground. Alexander' suggested that when the ground is completely saturated with water there is less passage of water over the phosphate rock and therefore less solution of fluorides. The fluoride content of Pulaski water varies from 0.2 to 1.3 ppm. The ground waters of the adjacent study area in the county have unknown fluoride values. The condition of the teeth of the children using the municipal water supply of Pulaski (0.2 to 1.3 ppm. F.) has been compared with the condition of the teeth of the children living outside of the city using ground water (wells or springs) of unknown fluoride content, to determine whether a correlation exists between the surface water supplies of known high intermittent fluoride content and the ground water supplies. Dean," Arnold,3 Klein,17 and many other investigators have shown that groups of children who consume waters containing small amounts of fluorine (0.5 ppm. or more) experience less dental decay than do comparable groups of children who use fluoride-free water. Arnold3 has shown that children who are born and reared in communities whose domestic water supplies contain more than 0.5 ppm. fluorine experience less dental caries than do children living in areas where the domestic water supply is fluoride-free. Arnold2 has proposed that water containing 0.5 to 0.7 ppm. fluorine in the southwestern United States might have an effect equal to that of water of 1.0 to 1.5 ppm. fluoride in the north central section, and concluded that only a small amount of fluorine is necessary to produce the desired effects. McKay,33 Churchill,30 Smith,34 and Dean6' 7, 1 have demonstrated that small quantities of fluorine consumed in a water supply during tooth development may result in mottled enamel, 1 ppm. representing a safe threshold.31 Russell'9 has reported a study of a community in which the water supply was accidentally fluoridated to a mean level of 1.15 ppm. fluorine for eighteen months. On the basis of caries prevalence, he found no demonstrable inhibition of dental caries in the younger children of the community. In the same group he did find that 1 per cent of the girls and 5 per cent of the boys had