BY DR. TERRY GAFF Saturday, 15 January 2011
There are lots of old sayings that are brought to mind by current events. For example, “Sleep tight — don’t let the bedbugs bite” seemed to have some relevance recently in many hotels and college dorms.
Another old phrase is “Mad as a Hatter.” For this one, you might think of the recent remake of “Alice in Wonderland” or perhaps the Teacup rides in the Disney theme parks. However, it makes me think of mercury.
In the past, they used mercury to create felt, from which hats were made. It is thought that the chronic exposure to mercury caused the “hatters” to become confused and demented, that is, to go “mad.”
Although mad hatters are a thing of the past, the concern about mercury continues to be an issue for many people because of mercury-based dental filling, known as dental amalgam, which has been used by dentists for many years.
In view of this concern, an advisory panel to the U.S. Food and Drug Administration (FDA) concluded recently that there are no huge scientific flaws in the agency’s 2009 finding that dental amalgam is safe for adults and children aged 6 years and older.
Representing the professionals who use the product, the American Dental Association maintains that dental amalgam is safe and needs no further regulation by the FDA as a medical device.
At the same time, the panel’s request for more scientific data about vulnerable populations acknowledged the concerns of dental amalgam opponents, who try to link mercury exposure to dozens of diseases ranging from autism to Alzheimer’s disease.
It has already been established that at high enough levels, mercury exposure can damage the brain and kidneys. In fact, Norway, Sweden and Denmark have already banned the use of mercury-containing dental amalgam.
Mercury is not the only component of dental amalgam. It is composed of roughly 40 to 50 percent liquid elemental mercury and a powdered alloy of mostly silver, copper and tin.
The FDA believes that an individual with seven to ten amalgam fillings absorbs one to five micrograms of mercury per day. Amalgam opponents say this could be four times as high, meaning that tens of millions of people with these fillings could be at risk for health problems, based on the current reference exposure level (REL).
In addition, there is some question as to whether the FDA has set the REL too high because it was partially based on studies of industrial workers exposed simultaneously to mercury and chlorine gas, with the gas acting to reduce mercury exposure, thus skewing the numbers.
The panel called the chlorine gas argument a “red herring.”
Nevertheless, it advised the FDA to reexamine the scientific literature to reassess the REL and develop its own safe level for mercury exposure.
However, any change of the REL for mercury may have enormous consequences that extend far beyond the dentist’s office. This is because the Environmental Protection Agency uses the REL to regulate how much mercury that heavy industry can put into air and water, as well as to designate waste sites for its Superfund clean-up program. A lower REL could cost industries billions of dollars.
Health Canada states on its website that although dental amalgam generally does not pose a health threat, the primary teeth of children should be filled with a non-mercury material when feasible. Pregnant women, individuals allergic to mercury and those with impaired kidney function should avoid mercury-based fillings.
With the concerns about mercury, you might be wondering why it is used in dentistry at all. It is because of the amalgam’s superiority over tooth-colored composite fillings for restoring multiple surfaces and for its greater durability. In addition, its lower price has made mercury-containing amalgam the default material for poorer patients, who might not be able to afford more expensive fillings if amalgam were banned.
Of course, the best approach would be to prevent fillings with good dental care, including regular brushing, flossing and dental check ups. However, for most of us, even that fails occasionally.
If you are like me, you will count your fillings in the mirror before you even finish reading this column. You might even talk to your dentist about filling material options at your next dental appointment. However, rather than having my fillings drilled out and replaced, I plan to simply blame some of my “madness” on those fillings, whether they deserve it or not.
Dr. Terry Gaff practiced family medicine in Albion, Indiana for 17 years and is now medical director of the emergency department at Parkview Noble Hospital in Kendallville, Indiana and the Noble County EMS.
He is also the Noble County Coroner.