Historically, tooth fillings were a metal filling called an AMALGAM.  This restoration used Mercury to amalgamate or mix and bind other metals to form a substance that was condensed into the cavity space after the decay was removed.  The Mercury was used also to destroy the bacteria that might be left behind in the cavity space and to prevent re-decay by having a toxic substance in the interface of tooth and filling.  The Mercury is inert after 24-48 hours once the filling sets - hence research indicates no reason to remove the metal fillings.

Now, dental research developed a compound the combines a light cured resin and filler material to bond or adhere to the tooth enamel and dentin.  This system has advantages over the Mercury/amalgam fillings: 1) Mercury is not used, 2) helps hold the tooth together (limits breakage), 3) can be placed with limited tooth removal,  4) tooth colored.

Our office has not used the metal Mercury fillings for over 25 years – the benefit of composite tooth colored fillings seems to be well worth the more demanding expertise of placement these tooth-colored fillings require.  Also, there are many countries around the globe, that are making Mercury fillings illegal to use – the properties of Mercury are the main problem with metal fillings and its potential toxicity.