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At the beginning of the 20th century, dental caries were widespread and lead to serious tooth loss. In fact, having sound teeth was so important and such a rarity in the general population that the U.S. military made having a minimum of six opposing teeth a requirement during recruitment for WW I and II.
The first glimmer of an association between fluoride and oral health was observed by Dr. Frederick S. McKay in 1901. Noticing a brown stain on the teeth of his patients, Dr. McKay found that those who had these stains seemed to have less fewer caries. In 1909, Dr. F.L. Robertson noticed mottling on the enamel (the hard outer surface) of children's teeth after the digging of a new well—source of the local drinking water. It wasn't until 1930 that the well water was analyzed, and high concentrations of fluoride were found. Fluoride, a naturally occurring fluorine ion, is found in soil, foods, and water.
The brown staining and mottling were characteristic of fluorosis, an abnormal condition caused by excessive exposure to fluoride while a child's teeth are forming under the gums. It affects the formation of tooth enamel and can vary from very mild to severe. Very mild fluorosis is manifested as tiny, white spots on 25% of a tooth's surface. Mild fluorosis covers 26% to 50%, and moderate fluorosis compromises all of a tooth's surface. It is most often characterized by brown discoloration of the tooth. Severe fluorosis involves pitting of the enamel and more serious brown staining. Approximately 94% of dental fluorosis today ranges from very mild to mild.
Extensive studies of national water supplies have been conducted. It has been found that dental caries were fewer in cities with more fluoride in the community water supply. A 1945 field study was conducted in four pairs of cities to determine whether a low level of fluoride (between 1.0 ppm and 1.2 ppm) could prevent dental caries. The result was a 50% to 70% reduction in the number of dental caries in communities with fluoridated water; only 10% of the people had mild fluorosis.
In 1962, another study found an optimal fluoride level of 0.7 parts per million (ppm) to 1.2 ppm (warm climates, where water consumption is higher, vs. cooler climates, respectively). This fluoride level range was determined to combat dental caries and pose only a slight risk of mild fluorosis.
Water fluoridation was rapidly adopted in major U.S. cities. About 46% of all public water supplies, however, remain non-fluoridated. Still, there has been a drastic reduction in the incidence of dental caries among children, in 2000 about half of all American children aged five to 17 years have never had a cavity in their permanent teeth. Adults also have experienced a 20% to 40% reduction in dental caries on enamel surfaces, as well as on exposed root caries—a condition peculiar to persons with gingival recession. Some of the earlier studies from
Author Info: Janie F. Franz, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Nursing and Allied Health, 2002
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