One in a million : the first community trial of water fluoridation

During the 1930s and early 1940s, H Trendley Dean and his colleagues working from the US National Institutes of Health published a series of epidemio-logical studies describing the relationship between the level of fluoride naturally present in public drinking-waters and the prevalence and severity of dental fluoro-sis and dental caries. Dental fluorosis is a white -- and in more severe cases an unsightly brown -- developmental defect of dental enamel, while dental caries is a post-eruptive disease of the teeth caused by the action of certain oral bacteria on ingested dietary sugars. As the natural fluoride level rises from low levels (less than 0.1 mg/l), so the prevalence and severity of dental fluorosis increase while the extent of dental caries -- usually summarized by the index of the mean number of decayed, missing and filled teeth (DMFT) -- falls. Dean and his colleagues suggested that in temperate climates and at a fluoride concentration in drinking-water of around 1 mg/l, the level of dental caries was substantially less than that associated with low levels of fluoride, while the level of dental fluorosis had increased but only to a level that was clinically and aesthetically of no concern.