Replacements for decayed or lost teeth have been produced for millennia. The Etruscans made skillfully designed false teeth out of ivory and bone, secured by gold bridgework, as early as 700 b.c. Unfortunately, this level of sophistication for false teeth was not regained until the 1800s. During medieval times, the practice of dentistry was largely confined to tooth extraction; replacement was seldom considered. Gaps between teeth were expected, even among the rich and powerful. Queen Elizabeth I (1533-1603) filled the holes in her mouth with cloth to improve her appearance in public. When false teeth were installed, they were hand-carved and tied in place with silk threads. If not enough natural teeth remained, anchoring false ones was difficult. People who wore full sets of dentures had to remove them when they wanted to eat. Upper and lower plates fit poorly and were held together with steel...