I suggest that anyone getting a tooth extracted that has an old Amalgam filling ,more than fifteen years old, save the tooth so it can be analyzed for mercury content.I read that old fillings often are < 10% hg,although they are >50% hg new. The percentages of other components ,in contrast, such as copper increase over time , showing hg vaporizes off fillings. Of course, the dentist probably wont want you to have it because ,now that it's out of your mouth, it's toxic.