Dental amalgams—boon or bane?

(First of two parts)

A dilemma healthcare professionals like doctors and dentists constantly face is how to balance the beneficial and potentially harmful side effects of all drugs and substances we give our patients. In fact, even placebo or “dummy pills,” which contain no active ingredients, have been shown to have side effects in clinical trials when the patients are “blinded,” or they don’t know whether they’re taking placebo or the active drug.

Another issue which Philippine dental experts, health officials and regulators are still trying to resolve is how to deal with dental amalgams, which are very useful as a dental filling material but contains mercury which scares a lot of health advocates because of its potential toxic side effects.

Dr. Vic Medina, dean of the University of the Philippines College of Dentistry, could only shake his head. “Reputable institutions worldwide have scrutinized the issue already for many years now,” he says, “and there is no dental amalgam controversy anymore outside of the Philippines.” He has provided me with a long list of annotated bibliography on the safety and cost-effectiveness of dental amalgams. I requested my research staff to get hold of the complete manuscripts of some of these studies.

‘Leached’ mercury

Advocates against them argue that amalgam fillings leach mercury into the mouth in small amounts daily; and over time, the level can reach toxic levels. Quickly going over the studies looking into this shows that the amount of “leached” mercury varies widely, and there’s no agreement among experts if such amount poses significant health risks.

The United States Food and Drug Administration (FDA) reported that the amount is around 1-3 micrograms (µg) per day, which is not significant to cause mercury toxicity. In a 2002 report, the FDA said that “no valid scientific evidence has shown that amalgams cause harm to patients with dental restorations, except in the rare case of allergy.”

The Federacion Dentaire Internationale (FDI), a federation of dental associations in the world, also conducted a meta-analysis of the literature on mercury toxicity and concluded that there is no documented scientific evidence on any significant side effects from dental amalgams except in extremely rare cases of mercury hypersensitivity or allergy.

Safe

During its general assembly in 2009, the FDI stated that “amalgam is a safe, widely used and affordable dental filling material and currently serves the oral health needs of the majority of communities around the world, particularly those most disadvantaged and in need of dental treatment.”

FDAs in other countries have similar findings and sentiments, and allow the use of mercury in dental fillings. In a few countries like Norway and Denmark, dental amalgams are not allowed due to environmental concerns on the disposal of unused dental amalgam, rather than the possible direct toxicity on humans.

The concern of many health advocates is that the use and disposal of amalgams by dentists are largely unregulated in many countries; and according to the World Health Organization (WHO), in some countries like the United Kingdom, mercury from amalgam and laboratory devices accounts for 53 percent of total mercury emissions. Experts recommend the use of separator equipment that could dramatically decrease the release of mercury into the public sewer system.

Those who advocate the use of amalgam like Dean Vic strongly believe that it is safe, durable, relatively inexpensive and easy to use compared to resin composites, which only last half as long as dental amalgams. Dental porcelain, another alternative, is much more expensive, and is beyond the reach of the average Filipino whose dental problems can be as bad as some of our pothole-ridden streets.

There are also some studies suggesting that bisphenol A, which is contained in composite resins, may have potentially significant hormonal side effects, which may actually be worse than what is feared with dental amalgams.

Locally, the dental amalgam issue has stirred a controversy when the Department of Health (DOH) came out with an administrative order (AO) in 2008 ordering the gradual phaseout of all mercury-containing devices in healthcare facilities and institutions due to potentially harmful effects on the nervous, digestive, respiratory, immune systems and the kidneys. The AO specified thermometers and sphygmomanometers (blood pressure apparatus). However, the AO wasn’t clear about the continued use of mercury-containing dental amalgam as a restorative material.

Position paper

Because of this ambiguity, the College of Dentistry of UP Manila, which is the only government-owned school of dentistry in the Philippines and is well-known for strictly practicing evidence-based dentistry, conducted a thorough study on the beneficial and harmful effects of dental amalgams. It came out with a position paper that supports the use  of dental amalgam fillings as  alternative materials.

The UP Manila dentists agree that there is no perfect filling material; as such, the dentist’s decision on what filling material to use should be based on the patient’s needs. They emphasize that they are aware that although dental amalgam fillings release dangerous mercury vapors, there is yet to be a clinical study directly linking dental amalgam to adverse effects to humans.

“As such, WE DO NOT RECOMMEND THE REMOVAL OF SOUND DENTAL AMALGAM FILLINGS,” the position paper said, apparently stressing it by writing the recommendation in capital letters.

Dean Vic says that there is a big body of experts worldwide including dental schools and practitioners, national dental organizations and regional/global federations, national institutes of health and regulatory agencies that support the continuous use of amalgams as a dental filling material. On the other hand, there is also a small group of very active health advocates who clamor for its total ban. “Who should we listen to?” Dean Vic asks.