Is Mercury in Dental Amalgam Fillings Toxic?
What is Dental Amalgam?
In use for over 150 years, silver amalgam, a mixture of various powdered metals (such as silver and tin) elemental Mercury, which binds them all together into a putty like material that is packed into teeth, replacing missing tooth structure lost forms a hard strong stable compound.
Why is Mercury Used in Amalgam Fillings?
Liquid mercury is the only substance known that is able to effectively bind the alloy particles together to form a strong, hard, and stable compound.
Mercury Toxicity, Dentistry, and The Environment.
Mercury toxicity has been a topic of concern for decades. Mercury is present naturally and as well as an introduced contaminant in the environment. The controversy regarding its use in the field of dentistry has been due to the fact that mercury is used in amalgam fillings. Mercury’s degree of toxicity of depends on its chemical form and route of exposure. It exists in three chemical forms: organic mercury, inorganic mercury, and elemental mercury.
Methylmercury is the most ubiquitous form of organic mercury. It accumulates and is found especially in fish and other aquatic life at the top of the food chain. It is the most toxic form of mercury as well as being the most toxic organic compound. It is widely used by humans and is a byproduct of many industrial processes. Organic mercury is readily absorbed through the digestive tract, penetrates membranes, and crosses to blood-brain barrier. It has a high potency for causing damage to the nervous system and kidneys. People are exposed to organic mercury almost exclusively by eating contaminated fish. Inorganic mercury has a variety of industrial uses. Unlike organic mercury, very little is absorbed through the digestive tract, and whatever is absorbed does not readily cross biologic membranes.
Elemental mercury is also known as liquid or metallic mercury. It is the form present in mercury thermometers, fluorescent bulbs and dental amalgam fillings. Unlike organic mercury, it is almost completely nontoxic when ingested orally, due to its lack of absorption through the digestive tract. Liquid mercury evaporates at room temperature and can produce mercury vapor. When inhaled, it is readily absorbed into the bloodstream.
Is Dental Amalgam Safe? What is The Controversy?
Dentists have been placing amalgam fillings for over 150 years. Dental amalgam was introduced to the United States in 1833 and the mercury toxicity controversy started immediately. The amount of information available on the topic is overwhelming and in can be difficult to find a clear answer. In the end it really comes down to whose science you want to believe.
The elemental mercury present in dental amalgams can release low levels of mercury vapor, which can then be inhaled. Exposure to high levels of mercury vapor can have adverse effects on the brain and kidneys. Since the 1990’s several agencies such as the CDC, FDA, and ADA have reviewed scientific literature in an attempt to find a link between dental amalgam and adverse health effects. It is known that amalgam fillings release small amounts of mercury vapor during placement and removal from teeth. They are known to also release low levels of mercury vapor during the action of chewing. Based on the reviewed scientific evidence, the FDA has concluded that amalgam fillings are safe for adults and children above 6 years of age. Even in people with as many as 15 surfaces of amalgam fillings, the amount of detectable mercury levels in their bodies were far below the lowest levels associated with harm. Clinical studies also failed to show a link between amalgam fillings and health problems.
Claims of diseases such as multiple sclerosis and autism being caused by amalgam fillings are based anecdotal evidence and creating or enforcing policies based on them is simply bad science. Some anti-amalgam advocates such as Huggins claim to be naturopathic or holistic and believe that mercury vapor is being released at toxic levels from amalgam fillings during the action of chewing. Unscrupulous dentists are using the Mercury Toxicity Scam to exploit their patients. They employ scare tactics with the use of inaccurate testing equipment such as the Jerome mercury detector, which gives a falsely high reading of mercury levels by giving a value for a cubic meter (obviously being a volume far greater than the mouth). Based on the results of inaccurate and unscientific tests these anti-amalgam advocates then conclude that the individual has toxic levels of mercury in their body in an effort to persuade a patient to have all the amalgam restorations removed, even if the restoration has no problem. Evidence shows that mercury content in the body is higher immediately after removal due to the release of mercury vapors during the removal process. This coincides strangely enough with most peoples’ anecdotal stories of their immediate health improvement following the removal of amalgam fillings.
What is our policy and philosophy?
Our office has not placed amalgam restorations for the past 10 years. This was a choice we made after very careful consideration of all of the true scientific evidence available and the successes and failures we’ve observed as professionals in the real life restoration of teeth. We believe that amalgam is an excellent restorative material, but our patients’ desire for more esthetic and natural appearing white fillings in addition external factors (environmental and disposal factors) have made it difficult for us to strongly advocate for its continued use.
All of our offices are currently amalgam or mercury free. We do often replace older amalgams as they begin to fail, or we will replace them at patients’ request for cosmetic purposes. We DO NOT advocate the removal of amalgams when they are in good condition in the absence of disease.
We most carefully look at the overall health of the people who are exposed to the highest amounts of mercury vapor, the dentists and assistants who remove older amalgam fillings all day. Evidence shows that even though members of the dental staff do contain a higher amount of mercury in their bodies, they show no increase in any of the diseases most commonly blamed on its use. Release of mercury into our environment, and into our food chain is not under dispute, and although the biggest polluters of mercury are coal-fired power plants and mining operations, we don’t dispute that less mercury in the environment is a good thing. We understand that this is a highly controversial topic. We have tried to show a balanced representation of the information available, so that you can make an informed and educated decision at your next dental appointment.
- Barrett, S. The "Mercury Toxicity" Scam: How Anti-Amalgamists Swindle People. March 2, 2006
- Yagiela, John A.. Pharmacology and Therapeutics for Dentistry, 5th Edition. Mosby, 082004.
- Gladwin, Marcia, Michael Bagby. Clinical Aspects of Dental Materials: Theory, Practice, and Cases, 4th Edition. Lippincott Williams & Wilkins, 3/14/12.