Dental Amalgam, Mercury Contamination and What You Need to Know

By Gerald P. Curatola, D.D.S. Oral Health and Wellness Expert, Clinical Associate Professor, NYU College of Dentistry

Posted on | By Gerald P. Curatola, D.D.S.

When considering the history and the polarized positions surrounding the ongoing use of mercury-containing fillings in dentistry, it could be argued that it is time to “stop the insanity.” Dental amalgam is actually comprised of four metals – mercury, silver, copper and tin – with mercury, its most toxic element, also being its most significant component, approximately 50% by weight. Once believed to be “locked into the filling itself,” mercury vapor is now widely recognized to be emitted from the filling surface, but the actual harm of this vapor has been highly contested. 


While the use of mercury-free fillings, such as tooth-colored composite resins and ceramics, are becoming more prevalent and better performing, approximately 46% dentists in the United States still use mercury-containing dental amalgam. Since the Civil War, mercury-containing fillings (often called “silver” or “amalgam”) continue to be used extensively to fill dental cavities. A 2006 poll of 2,590 US adults found that 72% of respondents were not aware that mercury was a main component of dental amalgam, and 92% of respondents would prefer to be told about mercury in dental amalgam before receiving it as a filling. This could be compared to being given a drug today by a pharmacy without the mandated FDA prescribing information (contents, possible side effects, etc.). Unfortunately, many dentists continue to place mercury-containing fillings, with many patients remaining uninformed of its mercury content. 

Complicating the matter of mercury-containing fillings is the important fact that the greatest exposure of mercury vapor to the patient (and dentist) is when dental amalgams are first placed in the tooth and when they are removed. 

Mercury use in health, consumer, and industrial products has declined precipitously in all products over the past 30 years, but in dentistry, this decline has only been slight, such that dental fillings jumped from 2% of all mercury products two decades ago to over 20% in 2001. In 1991, the World Health Organization (WHO) confirmed that mercury contained in dental amalgam is the greatest source of mercury vapor in non-industrialized settings, exposing the concerned population to mercury levels significantly exceeding those set for food and for air. WHO also went on to state that mercury contained in dental amalgam and in laboratory and medical devices accounts for about 53% of total mercury emissions –  and about one-third of the mercury in the sewage system comes from dental amalgam flushed down the drain. The Association of Metropolitan Sewerage Agencies (AMSA) studied seven major waste-water treatment plants and found that dental uses were "by far" the greatest contributors of mercury load, on average contributing 40%, over 3 times the next greatest contributor. The Environmental Protection Agency (EPA) also declared that dental amalgam is a major source of mercury contamination in waste-water.

The health debate surrounding mercury-containing fillings is equally concerning and confusing. Peer-reviewed scientific studies have come to opposite conclusions on whether the mercury exposure from amalgam fillings causes health problems. While it would be appropriate that any medical device should be proven 100% safe BEFORE being placed in the human body, and all potential health concerns from a known toxic environmental hazard be fully investigated, dental amalgam continues to be used until enough ongoing research is accepted proving it is unsafe and unsuitable. 

The Food and Drug Administration (FDA) has stated that, “There is limited clinical information about the potential effects of dental amalgam fillings on pregnant women and their developing fetuses, and on children under the age of 6, including breastfed infants.” In 2002, the FDA also issued a statement on dental amalgam, which asserted that "no valid scientific evidence exists that has shown that amalgams cause harm to patients with dental restorations, except in the rare case of allergy.” Nevertheless, a 1991-1997 study of 3,162 patients in Sweden and Germany found that 719 of those with mercury fillings, or 23%, tested positive for systemic allergic sensitivity to inorganic mercury on the MELISA lymphocyte proliferation test. A paper published as part of a 1991 National Institutes of Health (NIH) conference on side effects of dental restorative materials also reported a 22.53% incidence of allergy in subjects who had amalgam fillings for more than five years. A 2003 monograph on mercury toxicity from the World Health Organization (WHO) concluded that studies on humans and animals demonstrated that dental amalgam contributes significantly to mercury body burden in humans with amalgam fillings, and dental amalgam is the most common form of exposure to elemental mercury in the general population.

In 2008, the FDA issued an advisory, warning pregnant women and children (the most sensitive population to mercury) about dental amalgam containing mercury, and posted this warning on their website. However, after significant debate, in addition to reclassifying dental amalgam as a Class II (more risk) medical device, this warning was amended in 2009 to: “Pregnant or nursing mothers and parents with young children should talk with their dentists if they have concerns about dental amalgam."

Most recently, the American Public Health Association (APHA) issued a policy statement, in conjunction with the American Dental Association (ADA), affirming that “dental amalgam is safe and effective in treating cavities.” It pointed out that since amalgams are less expensive, easy to place and extremely durable, it also argued that curtailing amalgam’s availability could have “negative health effects” in low-income areas that need low-cost fillings. 

All this brings to mind the expression, “The operation was a success, but the patient died.” While the continued use of dental amalgam has strong support as a restorative success, shouldn’t we also continue to be concerned if the patient and our planet could be negatively impacted by a known toxic element? If that is true, then the debate should continue and the retirement of this old standard in dentistry should be considered as we look toward safe and stable restorative alternatives.

Until then, here are five top considerations for those who should speak to their dentist about having their amalgam fillings removed, and five top considerations for the best protective measures and nutritional support before and after amalgam removal and replacement. As I mentioned, the greatest exposure of mercury vapor to the patient (and dentist) is when dental amalgams are first placed in the tooth and when they are removed. If you are concerned about your silver fillings, have your dental team examine your fillings to determine whether or not they are intact, and have a conversation with your dentist about the potential health risks of keeping or removing amalgams. 

Considerations for dental amalgam removal:

  1. Patients who have recurrent decay and/or defective margins around their dental amalgam fillings. 
  2. Patients who have 8 or more dental amalgam fillings.
  3. Patients who have exhibited an allergy or sensitivity to dental amalgam (lymphocyte proliferation test).
  4. Patients who have bruxism (grind their teeth).*
  5. Patients who consume high quantities of acidic foods and carbonated beverages.*

*demonstrated to cause prolonged higher levels of exposure to mercury vapor from dental amalgam restorations.


Protective measures and nutritional support for dental amalgam removal:

  1. Your dentist should always use a proper isolation technique with a dental rubber dam to minimize exposure to mercury contact and/or swallowing amalgam debris.
  2. Check that the dentist is using a high-speed and low-speed suction device to rapidly remove amalgam, and ask for an oxygen nose mask if available to reduce the risk of inhaling mercury vapor during removal.
  3. Take chlorella (fresh water algae tablets or powder), a chlorophyll-rich nutritional supplement shown to assist with mercury (and heavy metals) excretion from the intestines, before and after amalgam replacement.
  4. Vitamin C has also been shown to be effective in assisting with mercury elimination. Take after meals and apart from chlorella.  
  5. Cilantro is the most celebrated herb to assist with intracellular mercury elimination. 

Article written by Gerald P. Curatola, D.D.S.
Oral Health and Wellness Expert, Clinical Associate Professor, NYU College of Dentistry