Here's some additional info on Charcoal:

Activated Charcoal

The dentist actually used charcoal and powdered chlorella during our amalgam removal. He poured this mixture under our tongues before he placed the rubber dam in our mouths. This way, if any mercury leaked beneath the rubber dam, it would get absorbed by the charcoal/chlorella mix. Before the next quadrant, he had us spit the mix out and rinse our mouths before he put a fresh mix in.

Hope this helps,