Amalgam is an alloy that has been used to fill decayed teeth for a very long time. People mostly say grey fillings when referring to this kind of filling. This alloy contains silver, copper, tin and mercury.
It’s the mercury that worries people who have grey fillings in their teeth. There are dentists who totally discourage amalgam fillings, and instead recommend composite fillings, or porcelain or gold inlays.
Is it absolutely necessary to remove all your grey fillings if you have some in your mouth?
There are countries that have banned amalgam, but several professional dental associations, including the ones of Canada and the United States, that do not totally discourage amalgam use for fillings. So there is no need to be alarmed if you have grey fillings, and you can keep them in your mouth as long as they are in good shape and do not need to be changed. But when it comes time replace them, it would be preferable to chose another filling material, mainly white composite fillings, which are more aesthetic and do not contain mercury.
Full Article: Is amalgam in teeth (grey fillings) bad for your health?
In French: Mercure dans les plombages dentaires