Hot Topic- Mercury
Dental amalgam fillings are created by mixing elemental mercury (between 43 percent and 54 percent) and an alloy powder composed mainly of silver, tin and copper. In its elemental form, mercury can be toxic, although this form is far less toxic than organic mercury, such as the methylmercury found in some seafood such as tuna or swordfish. This has generated discussion about the potential risks and toxicity of the mercury in dental amalgam.
When mixed as an alloy the vast majority of the mercury in the dental amalgam becomes stable, however a miniscule amount is released as vapor. How much vapor is emitted depends on the number of fillings you have. Miniscule amounts of this vapor can be inhaled and enter the bloodstream where it may then be taken throughout the body. The amounts absorbed are well below safety limited set by the federal government and are harmlessly excreted from the body. Should you swallow a bit of an amalgam filling, the mercury within it is very poorly absorbed and typically does not enter the bloodstream and is excreted.
Scientific research continues on the safety of dental amalgam. Many public and private agencies reconsider this issue on an on-going basis. The U.S. Food and Drug Administration (FDA) and other public health organizations have investigated the safety of dental amalgams and concluded that "no valid scientific evidence has shown that amalgams cause harm to patients with dental restorations, except in rare cases of allergy." The World Health Organization (WHO) reaches a similar conclusion, and the U.S. Centers for Disease Control (CDC) maintains that "At present, there is scant evidence that the health of the vast majority of people with amalgam if compromised, nor that removing amalgam fillings has a beneficial effect on health." While questions have been raised concerning the safety of amalgam fillings, no public agency has found evidence to support discontinuation of the material and the FDA places no restrictions on their use.
The above information is from the ADA Dental Filling Facts brochure.