When a tooth is cracked, broken or damaged from decay a crown may need to be placed onto the tooth to restore the tooth properly. A crown is a long-term covering that fits over the original tooth. Crowns can be made of porcelain, gold and other metals. Crowns made of all porcelain typically have the most realistic appearance. Crowns can be used to whiten, reshape, and realign existing teeth, adding to a healthy and vibrant smile.