Kendall is partial-ly right (get it? partial?). Anyway, a laser scan of one of Washington's four known sets of dentures, done at the National Museum of Dentistry in Baltimore, MD revealed: "The dentures are made from gold, ivory, lead, human and animal teeth (horse and donkey teeth were common components). The dentures had springs to help them open and bolts to hold them together." http://www.msnbc.msn.com/id/6875436/

Here's another article, possibly the one where Kendall got the info about hippopotamus ivory. Human teeth were in that set of dentures also. Another set was made partly of gold: http://www.americanrevolution.org/dental.html