December 8, 2006
In the early 1930s, several public health dentists wondered whether the fluoride levels of the drinking water in Colorado Springs might account for the unusual discoloration of the tooth enamel of some residents. Dr. Trendley Dean, one of the dentists who later would serve as the first NIDCR director, called the condition “dental fluorosis.” Dean and his colleagues later confirmed their suspicion and found that children who ingest excessive amounts of fluoride as their teeth develop may decrease the mineral content of their underlying tooth enamel. This change can cause white opacities or, in severe cases, pits and/or brown mottling of the enamel. However, because of the many substantial scientific and logistical challenges of assessing total fluoride intake during the first few years of life, still unclear nearly 75 years later is the specific level of fluoride intake necessary to cause fluorosis. In the October issue of the journal Caries Research, NIDCR grantees and colleagues help to answer the question by analyzing the fluoride intake of 628 children over several years from multiple sources including water, beverages, selected foods, and dentifrices. The scientists found the prevalence of fluorosis (almost all mild) was higher above a cumulative average daily intake during a child’s first three years of 0.04 milligrams fluoride/kilogram of bodyweight, with greater risk above 0.06 mg fluoride/kilogram bodyweight. Below this level, the risk was considered low. The scientists noted that the relationship between total fluoride intake and fluorosis was apparent over time for both the maxillary central incisors and first molars. They also found that the development of fluorosis appears to relate to the duration of cumulative exposure to high amounts of fluoride.