Very controversial subject, Mercury should also be avoided in denatl fillings, do NOT except and filling that has any mercury...amalgamom fillings (the silverish looking ones) contain mercury, AVOID them!
I had mine removed, I had some fillings in the back of my teeth and had them replaced with the tooth color fillings....you don't want that garbage leaking into your blood....I belive they are already banned in CA and European countries.
The dentists don't warn us they just stick that crap in our mouths and if it is not done carefully it can be especially dangerous, this crap could play a key role in many nervous system disorders, scary stuff.