Dental crowns are fixed to the outer surface of the tooth to restore shape, strength, function and appearance. They encase a tooth that has been badly damaged or decayed and are cemented on to the surface of the teeth. Since dental crowns cover the entire visible aspect of a tooth, a dental crown in effect becomes the tooth’s new outer surface. Crowns can be made out of porcelain, zirconia (a very hard ceramic), metal (a gold or other metal alloy), or a combination of both.