Henry Trendley Dean (August 25, 1893 – May 13, 1962[1]) was the first director of the United States National Institute of Dental Research and a pioneer investigator of water fluoridation in the prevention of tooth decay.

At the urging of Frederick McKay and others concerned with the brown-staining of teeth in certain regions of the country, Dean was asked to make this his first assignment at the Institute in 1931.

In other words we are dealing with a low-grade chronic poisoning of the formative dental organ in which case some individuals may show a more severe reaction than others having a comparable fluorine intake."

Dean's professional life was spent searching for an optimal level of fluoride that would prevent tooth decay yet avoid staining or otherwise damaging teeth.

In 1952, McKay and Dean were presented with the Albert Lasker Award for Clinical Medical Research by the American Public Health Association for their work with fluoride.