While dental amalgam has been in use for well over a century, some controversy has arisen in recent decades regarding possible toxicity due to its mercury content. The internet is rife with articles claiming that silver fillings are causing a plethora of disease processes. ‘Holistic’ dentists warn about the inherent risk of these restorations, imploring their replacement. Being a naturally occurring element found in water, air and soil, we are all exposed to mercury, yet the tiny amount of mercury vapour released from dental amalgam pales in comparison to exposure from other sources such as fish.
What is amalgam?
Amalgam, the classic dental filling material, is an alloy composed of varying amounts of mercury, silver, tin and copper. Once bound together these metals form a paste that quickly hardens, with the contained mercury enclosed in its structure. Being easy to place, reliable, durable and inexpensive, these restorations are used primarily for posterior teeth where esthetics is less of a concern. So why all the controversy?
Logic
The dental profession has been targeted by some groups and individuals who maintain that dentists are self-serving and complicit in continuing to support the use of amalgam. In the words of renowned galactic scientist Mr. Spock, this notion is totally “illogical.” If dental amalgam poses a significant health hazard dentists should be at greatest risk, as occupational exposure over decades far exceeds that of most individuals. To date there is a lack of evidence suggesting dentists suffer from more detrimental mercury related health effects than the general population. Despite the completely unfounded myth surrounding the profession and suicide, dentists on average have a longer life expectancy as compared with other occupations. From an economic perspective, dentists can generate more income by placing costlier, less durable white fillings. Indiscriminately replacing amalgam restorations based on unsubstantiated claims would provide most practitioners with more work than they could handle.
So what's a dentist to do?
Perception versus reality
I'm often asked by patients whether or not to replace existing amalgams. And while removal of these fillings may expose people to greater doses of mercury than if left in place, some medical conditions, including sensitivity or allergy to amalgam, though extremely rare, do warrant replacement.
More typically, my answer is based on a combination of two guiding principles:
1) Protocols set forth by professional regulatory bodies:
The FDA, considers dental amalgam fillings “safe for adults and children ages 6 and above” and “does not establish an association between dental amalgam use and adverse health effects in the general population.”
According to l’Ordre des dentistes du Québec, "The replacement of a clinically adequate, functional and asymptomatic amalgam restoration is not justified based on current scientific data."
2) Patient desires and concerns*
When considering this factor dentists must balance their Hippocratic oath to "do no harm" with a patient’s right to determine what is in their mouth. In today's ever increasing appearance conscious world, many people prefer to have esthetic colored fillings. And that is their choice. Practitioners must caution patients that replacing an amalgam may subject dentition to post operative sensitivity while potentially further weakening tooth structure. Only after obtaining informed consent and having assessed acceptably low risk based on clinical judgment should a dentist accede to a patient's request to replace amalgams for purely cosmetic reasons. Veritably, dentists must also appreciate that despite assurances, some people remain convinced that amalgam poses a serious health hazard, leading to increased anxiety. This "nocebo effect" can have serious detrimental effects to a person's overall health and well-being, justifying replacement.
Evidence - based
Being scientifically trained professionals, dentists rely on well controlled, reliable studies when choosing treatment options. ‘Evidence - based dentistry’, now more than ever has become the accepted standard. The dental profession does not bury its head in the sand and encourages more research regarding potential adverse effects to health from amalgam. Not only is this in the best interest of patients, but dentists’ as well. With considerable improvements in mercury-free posterior composite resin restorations, concerned patients can choose these for new fillings. But as things presently stand, based on best available, credible scientific evidence from numerous randomized clinical trials, there is no reason to systematically replace existing, clinically sound amalgams. Patients should seriously question any practitioner who advises otherwise.
*authors opinion only
Dr. Mark Grossman is a practicing dentist and likes to take a bite out of nonsense when it comes to dental issues.
