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.

Amalgam allergies are extremely rare reactions to the mercury used in the most popular form of dental filling.  The condition is so unusual that fewer than 100 cases have ever been reported, according to the American Dental Association.

Amalgam has been used for more than 150 years to repair teeth damaged by decay. The amalgam itself is a mixture of equal parts liquid mercury and alloy powder containing silver, tin, and copper. Sometimes, lesser amounts of zinc, palladium or indium also are used. Mercury is the only element known to bind together these metals in a way that can be used to fill a cavity (a small hole in a tooth caused by tooth decay).

Dentists long have preferred working with amalgam because of its relatively low sensitivity to moisture, such as saliva. This means dentists do not have to be quite as precise when placing amalgam, as it is more durable and “forgiving” than other substances used in tooth repair.  

An amalgam allergy occurs when the immune system becomes sensitized to a component in amalgam and then mistakes the substance as a foreign invader. The immune system then attacks the substance, producing symptoms of an allergic reaction (e.g., skin rash, itching). The substance in amalgam that is a potential trigger for this allergic reaction (allergen) is liquid mercury. Individuals with this condition must have other restorative materials (e.g., resin, porcelain, gold) used on them during dental procedures.

Patients who suffer amalgam allergies typically have a personal history or family history of allergies to metals.

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.

Symptoms of an amalgam allergy appear within hours to days of exposure and usually resolve on their own. They include:

• Skin rashes in the oral, head and neck area
• Itching
• Swollen lips
• Localized eczema-like lesions in the oral cavity

In addition to compiling a medical history and a list of symptoms, a physician trying to diagnose an amalgam allergy will conduct a full physical examination of the patient.

Because amalgam allergy symptoms resemble those of a skin allergy such as contact dermatitis, most physicians use a skin patch test to diagnose amalgam reactions. In this test, an absorbent pad is soaked with an allergen such as mercury and taped onto the skin of the patient for 24 to 72 hours.

Blood tests cannot easily detect amalgam allergies and are not often used in the diagnosis of this condition.

Symptoms related to amalgam allergy usually require no treatment and will disappear on their own within a few days of exposure. However, in some instances an amalgam filling will have to be removed and replaced with a filling made of another restorative material, such as resin, porcelain or gold.

The best way for a dentist to prevent an amalgam allergy when repairing a tooth is to use another substance, such as tooth-colored resin, porcelain or gold fillings. However, these substances are both more expensive and less pliable than amalgam. There is no single alternative to amalgam that can be used in all restoration procedures. Different substances are used depending on the tooth to be repaired and the size of the repair.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctors the following questions related to amalgam allergies:

1. Do my symptoms indicate an amalgam allergy?
   
   
2. How will you determine if I have an amalgam allergy?
   
   
3. What treatment options are available to me?
   
   
4. Does this condition pose a danger to my overall health?
   
   
5. Will I have to replace my amalgam fillings?
   
   
6. What alternatives to amalgam fillings are available to me?
   
   
7. When can I expect my symptoms to subside?
   
   
8. Are my children more likely to have an amalgam allergy because I have the condition?
   
   
9. How can I tell the difference between an amalgam tattoo and a cancerous lesion?