Bridges are used to replace teeth that are missing. They usually consist of a replacement tooth (or teeth) supported by a crown on each of the two teeth on either side of the missing one such that the two crowns and the replacement tooth become one piece. Variations include cantilevered bridges which are only supported on one side and resin-bonded bridges which use thin metal “wings”cemented onto the non-visible surface of the adjacent tooth/teeth instead of crowns. They can be made of Gold, Gold and Porcelain (where the gold cannot be seen) or entirely of porcelain/ceramic.