Crowns are used to cover and protect damaged teeth. Crowns are often placed on teeth that are broken, stained, poorly shaped, or misaligned. Crowns are also placed on teeth with large damaged fillings and teeth that have had root canals. Crowns can be made of metal, composite resin, gold, porcelain, or porcelain fused to metal. Composite resin is used to create crowns for teeth that are highly visible. These crowns can be customized to match the natural tooth structure using a special color-matching system.