Amalgam allergy is a very rare condition in which a patient reacts to the small amounts of mercury contained in amalgam dental fillings. Fewer than 100 cases of such a reaction have ever been reported, according to the American Dental Association.

Amalgam fillings are more commonly known as “silver” fillings. These fillings are made of a mixture that is equal parts:

• Liquid mercury. A substance that causes the rare allergic reaction in some people.
  
  
• Alloy powder. Usually contains silver, tin and copper. Sometimes, lesser amounts of zinc, palladium or indium also are used.

In most cases, no medical attention is required to treat an amalgam reaction. Symptoms usually resolve within a few days. In rare instances, amalgam fillings may need to be replaced with another substance, such as tooth-colored resin, porcelain or gold.

Questions about the safety of amalgam are not limited to allergies. For years, a debate has raged in the dental community over whether or not the mercury used in amalgam can have toxic effects on the body. Most experts and public health agencies – including the American Dental Association, U.S. Centers for Disease Control and Prevention, and U.S. Food and Drug Administration – maintain that amalgam is safe and point to the substance’s 150-year track record as the primary material used in tooth repair.