Mercury can be toxic (poisonous), even lethal, in high doses. For years, controversy has raged about whether or not the mercury in amalgam presents health risks to the human body. Most experts and public health agencies – including the American Dental Association, the U.S. Centers for Disease Control and the U.S. Food and Drug Administration – have concluded that the levels of mercury in fillings are not high enough to harm patients.

However, a vocal minority of dentists and researchers insist such assurances are unfounded and cite amalgam as a major lurking threat to people’s health. Many opponents to amalgam use have blamed the substance for a variety of general health problems, including nerve damage, autism, Alzheimer’s disease, multiple sclerosis, kidney problems, birth defects and compromised immunity. However, as to date, studies have been unable to link the use of amalgam with any medical condition.

Studies indicate that use of nicotine chewing gum long-term (over two years) combined with a large number of amalgam fillings may increase mercury levels in the body. Adverse health effects have not been reported. People who use nicotine gum long-term should discuss the potential health effects with their physician.

An amalgam tattoo (focal argyrosis) is a gray-pigmented area in the gum or cheek area that results from filling particles that have become imbedded in the tissue. This discoloration, which also can appear on the tongue or roof of the mouth, is flat and usually small – no more than a few millimeters long.

A large percentage of people who have amalgam fillings also have amalgam tattoos, although many probably are not aware of them. These are harmless, presenting no health risk. An amalgam tattoo can only be removed surgically. Dentists can reduce the chances of creating an amalgam tattoo by using a rubber dam while working on teeth. A dam is a flat piece of latex that isolates the teeth to be worked on from the rest of the mouth.

Some people confuse a cancerous lesion for an amalgam tattoo, which looks similar. If the discoloration changes in size or shape, it should be examined by a physician.

Amalgam allergy symptoms resemble those of skin-related conditions such as contact dermatitis. This is a skin rash that occurs when an allergen (a substance the body perceives as a threat, causing an allergic reaction) or irritant comes into direct contact with the skin, triggering an allergic reaction.