A dental crown is basically a cover for a tooth to protect it. Sometimes people refer to it as a cap. A crown is necessary for a tooth any time the tooth is missing more than 50% of the tooth structure. Therefore, in the case of a broken tooth, a tooth with decay, or a tooth with large silver filling, a crown may be recommended. A crown can also be used for cosmetic reasons. Most of the "Hollywood" smiles seen on tv are a result of crown work on front teeth. So crowns can serve two purposes, to protect your teeth or give you a "Hollywood Smile."