They can be made of full ceramic, full metal or a combination of porcelain and metal. For the metal portion, there are also various options available depending on the amount of gold content of the alloy. Newer material such as zirconia, that is whitish or tooth-coloured, has improved strength over other tooth-coloured materials. The material will perform well when they are used for the right indications. For example, gold or zirconia is usually used for the posterior teeth whereas more translucent full ceramic material is preferred for the front teeth. The price of the crown is also dependent on the material used. Crowns and bridges can last for a long time if they are well maintained.