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H. Trendley Dean, D.D.S.

m841b1f1.gif (5264 bytes)In 1931, dental surgeon and epidemiologist H. Trendley Dean (August 25, 1893-May 13, 1962) set out to study the harm that too much fluoride could do; however, his work demonstrated the good that a little fluoride could do.

Henry Trendley Dean grew up in East St. Louis, and received his D.D.S. from the St. Louis University School of Dentistry in 1916. After 1 year in private practice, Dean joined the Army, serving in a number of military camps stateside before going to France. In 1919, Captain Dean returned to private practice, but 2 years later joined the Public Health Service as acting assistant dental surgeon. During the next 10 years he served in Marine hospitals around the country, studied for a year at Boston University, and developed a reputation as both a skilled dental surgeon and researcher. In 1931, Dean became the first dental scientist at the National Institute of Health, advancing to director of the dental research section in 1945. After World War II, he directed epidemiologic studies for the Army in Germany. When Congress established the National Institute of Dental Research (NIDR) in 1948, Dean was appointed its director, a position he held until retiring in 1953.

The National Institute of Health (NIH) had hired Dean in 1931 to conduct a major study of mottled enamel. The team that Dean assembled reflected an interdisciplinary approach. The study required accurate assays of fluoride in water, so he enlisted Dr. Elias Elvove, senior chemist at NIH, who developed a technique for measuring the presence of fluoride in water to an accuracy of 0.1 ppm. He also hired experts in animal dentistry, dental pathology, and water chemistry. As accurate data on the incidence of fluorosis emerged, the apparent correlation between mottled teeth and lower caries rates grew more compelling. As early as 1932, Dean observed that individuals in an area where mottled teeth was endemic demonstrated "a lower incidence of caries than individuals in some nearby non-endemic area." By 1938, determining the prophylactic properties of fluoride became the study's primary focus.

Dean's legacy comes almost entirely from his association with the introduction of fluoridation, yet fluoride constituted only a small part of his professional activities. He also studied the effects of radium poisoning on alveolar bone; developed a program to study the prevention and cure of Vincent's angina (trench mouth); and undertook various studies of the causes, prevention, and cure of dental caries. More important, he played a major role in shaping federal participation in basic dental science research at the NIDR, integrating investigations of dental health into mainstream medical research. As he stated in a national radio address in 1950: "We can't divorce the mouth from the rest of the body."

Selected Bibliography

Harris RR. Dental science in a new age: a history of the National Institute of Dental Research. Rockville, Maryland: Montrose Press, 1989.

National Institute of Dental and Craniofacial Research, National Institutes of Health. The fluoride story. Available at Accessed October 19, 1999.

Martin B. Scientific knowledge in controversy: the social dynamics of the fluoridation debate. Albany, New York: State University of New York Press, 1991.

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