Mercury Fillings May Be Less Toxic: Caution Still Needed

Posted on 12. Jan, 2010 by wisdom in Health

A new study on the surface chemistry of silver-colored, mercury-based dental fillings suggests that the surface forms of mercury may be less toxic than that which was previously thought.

Graham George and his colleagues note that mercury-based fillings (amalgams) have been used by dentists to repair teeth for over 100 years. In recent years, their use has become controversial because of concerns about exposure to potentially toxic mercury. Even so, mercury can potentially exist in several different chemical forms, each with a different toxicity.

Scientists analyzed the surface of freshly prepared metal fillings and compared these with the surface of aged fillings (about 20 years old) from a dental clinic. Fresh fillings contained metallic mercury, which can be toxic. Aged fillings, on the other hand, usually contain a form of mercury, called beta-mercuric sulfide or metacinnabar. This form is unlikely to be toxic to humans.

The scientists found that the surfaces of metal fillings seem to lose up to 95% of their mercury over time. Loss of potentially toxic mercury from amalgam may be due to evaporation, exposure to certain foods, exposure to dental hygiene products, or some other causes.

Even so one should be cautions as exposure to mercury as it changes chemical forms over time is still a concern.

George et al. The Chemical Forms of Mercury in Aged and Fresh Dental Amalgam Surfaces. Chemical Research in Toxicology, 2009; 22 (11): 1761 DOI: 10.1021/tx900309c