Though widely used in the past, amalgam fillings, which are equal parts silver and mercury, have received a bad rap as of late. Mercury toxicity has been linked to neurological damages, gastrointestinal problems, immune system weakening, kidney damage, blood cell disorders, multiple sclerosis, Alzheimer's disease, and Parkinson's disease. Studies have shown that the average person receives far more exposure from existing amalgam fillings than from say, certain types of fish, which we are advised to consume rarely.