A crown is a man-made prosthetic tooth that is used to restore and protect an existing tooth. It may be used to restore and preserve a decayed, broken, or cracked tooth. Crowns may also be used to correct some cosmetic tooth problem, giving you a better smile. Crowns come in several different material types; they can be all metal, metal base with a porcelain covering, or all-porcelain. Using an all-porcelain crown can improve the overall natural appearance of the crown.