John Greenwood (dentist)

John Greenwood (May 17, 1760 – November 16, 1819) was an American fifer and dentist, serving as George Washington's personal dentist. He was responsible for designing Washington's famous dentures, which were not wood but carved from hippopotamus tusk. He invented the first known "dental foot engine" in 1790.

Greenwood served as a fifer during the American Revolutionary War at sixteen years of age. He served twenty months in Captain Theodore Bliss's company of the 26th Massachusetts Infantry Regiment, playing the fife in the Continental Army from 1775 to 1778. He was the grandson of Isaac Greenwood, a mathematics professor at Harvard University, and son of Isaac Greenwood, the first native-born American dentist.

A letter from Greenwood to Lt. General George Washington on his denture charges, dated 1799, is in the A.D. Black History of Dentistry Collection at Northwestern University.