When teeth are heavily decayed they may be too weak to survive with just a filling. By placing a crown, a tooth may be given a new lease of life. Even when a single tooth is lost a denture may not be required as a bridge can be made which spans the gap with a tooth attached to those next to the space. Sometimes when a single small tooth is lost at the front of the mouth a simple bridge can be made which has 'wings' that are glued to the back of the adjacent teeth. This results in less tooth being damaged by the drill.