Many people now prefer their teeth to be restored with metal free fillings largely because they look more natural and aesthetically pleasing than the traditional silver amalgam fillings. There is no proven health risk associated with amalgam fillings although some people still prefer to have them removed and replaced with white ones.
White fillings have always been considered less long lasting than amalgam fillings but there are now new materials available with properties comparable to silver amalgam. The life expectancy of a white filling can depend greatly on where it is in your mouth and your risk of tooth decay.
It is usually best to change fillings only when your dentist decides that an old filling needs replacing. If so you can ask to have it replaced in a tooth-coloured material.
This can vary, but they are mainly made of glass particles, synthetic resin and a setting ingredient. Your dentist should be able to give you more information about the particular material that they use.
Most dental practices offer white fillings as part of their routine treatments.