A crown is a dental restoration that completely caps or encircles a tooth or implant. Crowns are often needed when a large cavity threatens the ongoing health of a tooth or when a tooth has had a root canal treatment or is cracked. Crowns are also used to improve the strength or appearance of teeth. They can be made from many materials such as gold, metal alloy, zirconium, porcelain or a combination of these materials and are typically bonded to the tooth using dental cements. The resulting crown is the colour and shape of the existing teeth and if well made will look and feel like a normal tooth. While inarguably beneficial to dental health when indicated, each situation should be assessed by the dentist.