A crown is an artificial restoration that fits over the remaining part of a prepared tooth, making it strong and giving it the shape of a natural tooth. A crown is sometimes known as a 'cap'. The crown can last for many years depending on the health of the gum and tooth underneath. Crowns are an ideal restoration for teeth that have been broken, or have been weakened by decay or a very large filling. A crown can also be used where there are discoloured fillings, to improve the appearance of the tooth as well as where a tooth has had a root filling and will need a crown to protect what is left of the tooth. A front tooth crown is usually made from porcelain or a related material which will give the most natural looking appearance.