When a single tooth is missing, the two most common treatment options are the traditional tooth supported bridge and an implant supported crown. When a traditional bridge is used to replace a missing tooth, the adjacent teeth are cut down into peg shapes in order to fit the cemented bridge in place.
This method of tooth replacement can be very esthetic and functional for a period of time. However, a tooth-supported bridge does not replace the bone that previously surrounded the root. Since there is no longer a root to hold the bone in place, the bone deteriorates, or melts away.