The ADA says this is perfectly safe as the basis for amalgam fillings-- it combines with other materials to make it stable
In an ADA rebuttal published by the Business Journals, ADA .... be done to keep 
you (and your dentist) safe during amalgam removal include: ... ART relies on 
adhesive materials for the filling (instead of mercury) .... You said FDA would 
make an announcement on dental amalgam by ....