Dental fillings are the largest source of mercury in those who have several Amalgam fillings, causing as much as 10 times mercury exposure as those without, and commonly causing inflammatory conditions like depression, MS, Lupus, thyroiditis, arthritis, etc. http://www.flcv.com/dams.html
Other excitotoxins which can be a factor are Aspartame and MSG.
For those with Amalgam fillings where this is a factor, the majority significantly improve after Amalgam replacement and detox: http://www.flcv.com/hgrecovp.html