There is a trend now in dentistry to try and avoid the use of metal based substances in restoration procedures such as partial dentures and cavities. For many years, Amalgam has been used for fillings, but this is an alloy of quick silver and other metals and while it has proven to be long lasting, there are possible harmful effects as the metal slowly dissolves over time.  Other metals, such as nickel, often used in dentistry, have been shown to cause allergic reactions in some people.

The tendency now is to use bi-compatible and immuno-compatible substances so that the body will not reject them as foreign materials. An alternative now being used as a plastic enhanced with glass fibres or the use of porcelain. At the moment, the only option for filling larger cavities is the use of zirconium oxide, which has great strength and durability.