Crowns are a cosmetic restoration used to improve your tooth's shape or to strengthen a tooth. Crowns are most often used for teeth that are broken, worn, or have portions destroyed by tooth decay.
Crowns are "cemented" onto an existing tooth which fully cover the portion of your tooth above the gum line. In effect, the crown becomes your tooth's new outer surface. Crowns can be made of porcelain, metal, or both. Porcelain crowns are most often preferred because they mimic the translucency of natural teeth and are very strong.