Over the past 20 years, dental implant techniques have improved considerably and have grown in popularity. According to the American Dental Association, there were 5.5 million implants done by U.S. dentists in a one-year period ending in 2006, the most recent figures available. Dental implants are permanent titanium tooth roots used to support false teeth. On top of the roots, a dentist will place a post and, over that, a crown. If several teeth are being replaced, a bridge can be used instead of crowns.