Fluoridation

The process of adding fluoride to drinking water or another substance in order to reduce the occurrence of tooth decay.

Fluoridation was first introduced into the United States in the 1940s in an attempt to combat the serious problem of tooth decay. Today, more than half of the U.S. population drinks fluoridated water from public water supplies.

Tooth decay occurs when food acids dissolve the protective enamel surrounding each tooth and create a hole, or cavity, in the tooth. These acids are present in food, and can also be formed by acid-producing bacteria that convert sugars into acids. There is overwhelming evidence that fluoride can substantially reduce tooth decay. When ingested into the body, fluoride concentrates in bones and in dental enamel, which makes the tooth enamel more resistant to decay. It is also believed that fluoride may inhibit the bacteria that convert sugars into acidic substances that attack the enamel.

Opponents of fluoridation have not been entirely convinced of its effectiveness, and are concerned by possible side effects. They are also disturbed by the moral issues of personal rights that are raised by the addition of a chemical substance to an entire city's water supply. The decision to fluoridate drinking water has generally rested with local governments and communities and has always been a controversial issue.

Fluoride is present in most water supplies at low levels and nearly all food contains traces of fluoride. Toothpaste and mouthwash also contain added fluoride.

Infants who do not receive adequate amounts of fluoride in the water or formula they drink routinely have been given fluoride supplements beginning at about one month of age. In 1995, the American Academy of Pediatrics (AAP) recommended delaying such supplements until six months of age. Along with the American Dental Association, the AAP also revised downward the minimum level of fluoride at which supplementation is necessary. Studies now suggest that too much fluoride has resulted in an increase in the incidence of fluorosis, a discoloration or mottling of the teeth. While fluorosis can be unsightly, there is no evidence it weakens the positive effects of fluoride. Recent research also suggests that direct application of a fluoride gel to teeth with braces can ease bleeding of the gums and plaque buildup.

The issue of fluoridation was particularly controversial in the 1950s and 1960s, when heated debate surrounded the issue across the country. Critics pointed to the known harmful effects of large doses of fluoride that led to bone damage and to the special risks for people with kidney disease or those who were particularly sensitive to toxic substances. Between the 1950s and 1980s, some scientists suggested that fluoride may have a mutagenic effect (that is, it may be capable of causing human birth defects). Controversial claims that fluoride can cause cancer were also raised. Today, some scientists still argue that fluoridation is not without health risks.

Up until the 1980s the majority of research into the benefits of fluoridation reported substantial reductions (50-60% on average) in the incidence of tooth decay where water supplies had fluoride levels of about one ppm (parts per million). By the end of the decade, however, the extent of this reduction was being viewed more critically. By the 1990s, even some fluoridation proponents suggested that observed tooth decay reduction, directly as a result of water fluoridation, may only have been at levels of around 25%. Other factors, such as education and better dental hygiene, could also be contributing to the overall reduction in tooth decay levels. Fluoride in food, salt, toothpastes, rinses, and tablets has undoubtedly contributed to the drastic declines in tooth decay during the twentieth century. It also remains unclear what, if any, side-effects are of one ppm levels of fluoride in water ingested over many years. Although it has been argued that any risks associated with fluoridation are small, these risks may not necessarily be acceptable to everyone. The fact that only about 50% of U.S. communities have elected to adopt fluoridation is indicative of people's cautious approach to the issue. In 1993, the National Research Council published a report on the health effects of ingested fluoride and attempted to determine if the maximum recommended level of four ppm for fluoride in drinking water should be modified. The report concluded that this level was appropriate but that further research may indicate a need for revision. The report also found inconsistencies in the scientific studies of fluoride toxicity and recommended further research in this area.

Fluoridation

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