Is Mercury in Dental Amalgam Toxic?
Dental amalgam is a restorative material that has been safely used in dentistry to fill and restore tooth structure that has been lost through decayor other processes. Amalgam is made by mixing a powdered mixture of metals composed of particles of silver, tin and copper with elemental (liquid) mercury. Due to its silver color, it is also referred to as a “silver amalgam filling”.
Why is Mercury Used in Amalgam Fillings?
Liquid mercury is the only substance known that is able to effectively bind the metal particles together to form a strong, hard, and stable compound.
Mercury Toxicity, Dentistry, and The Environment.
Mercury toxicity and its use in dentistry has been a topic of concern for decades. Mercury is present in the environment as a natural substance and as a byproduct of certain industries such as mining. Mercury’s degree of toxicity depends on its chemical form and route of exposure. It exists in three chemical forms: organic mercury, inorganic mercury, and elemental mercury.
Organic mercury is most commonly known as methylmercury. It is the most common form of mercury found in the environment. Organic mercury is formed from inorganic mercury by aquatic microorganisms such as bacteria and simple plankton. These organisms incorporate mercury into the bottom of the food chain by binding carbon to mercury. The spread of organic mercury occurs as larger and larger fish feed on the smaller organisms that contain organic mercury. Organic mercury is readily absorbed through the digestive tract of larger fish and animals, including humans. It also penetrates membranes, and crosses the blood-brain barrier. It has a high potency for causing damage to the nervous system and kidneys. This is the most common form of mercury poisoning and people suffering from mercury toxicity are most commonly exposed by eating contaminated fish.
Inorganic mercury does not contain a carbon atom and 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 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. Elemental mercury’s toxicity occurs through the inhalation of its vapors. Patients are exposed to this vapor during the placement and removal of silver fillings, and through the action of chewing.
To clarify, toxicity occurring from exposure to mercury is either from ingestion of food containing organic mercury or inhalation of metallic mercury vapor, which can occur at the dental office.
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.
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 also known to 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.
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.
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 and there are no immediate needs to replace them. At our office patients can always request rubber dam placement to minimize exposure to mercury during amalgam removal.
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.