Crowns or “caps” are made when there is extensive damage to a tooth and when rebuilding a tooth with a filling material is unlikely to give a long-term result. Occasionally they are done just to improve the appearance of the tooth, but nowadays that task is accomplished wherever possible by veneers. Crowns can be made from a variety of materials. There are risks and workarounds to those risks you should be aware of. For more information, please go here.