NOTHING TO SMILE ABOUT
NOTHING TO SMILE ABOUT
Roughly 80 percent of all tooth restorations use dental amalgam, commonly known as "silver" fillings, which contain up to 50 percent mercury by weight. Various warnings about the toxicity of mercury have been raised. It is known that mercury is released from amalgam fillings, especially during chewing. Dorice Buck-Madronero, a member of Mothers & Others, asks, "Why is an EPA-regulated toxic substance like mercury allowed to be placed in our mouths?" Buck-Madronero is also a member of DAMS, or Dental Amalgam Mercury Syndrome, a nonprofit group concerned about the dangers of dental amalgam. A controversial article by M.F. Ziff, D.D.S., published in Advances in Dental Research (September 1992) states:
The medical scientific community is now in general agreement that ... the average daily absorption of mercury from dental amalgam is from 3-17 micrograms per day, and that the amalgam mercury absorption averages 1-6 times the average mercury absorption from dietary sources. But are there toxic effects associated with that exposure? That's where the controversy begins. (In addition, the amount of mercury released from fillings is in dispute -- the American Dental Association estimates between 2-4 micrograms per day). Some of the concerns about possible effects include:
Kidney dysfunction: One study by researchers at the University of Calgary in Canada (American Journal of Physiology, 1991) found that sheep treated with fillings had impaired kidney function. But human studies to date have showed no evidence of this.
Nerve damage: Numerous studies identify mercury as a neurotoxin. But it's unclear whether exposure from dental amalgam can cause neurotoxic effects. High levels of mercury have been found, in some studies, in the brains of people with Alzheimer's -- but that doesn't mean it causes the disease. A study of elderly women published in the JADA (November 1995) found no association between existing amalgams and tests of cognitive functioning.
Increased stillbirths and birth defects: The Calgary studies in sheep showed that mercury released from amalgam fillings was absorbed by the fetus during pregnancy; some studies in humans suggest an association between stillbirths or birth defects and mercury levels in the umbilical cord blood and in the mother's blood. However, no conclusive link has been established between adverse reproductive effects and mercury exposure through amalgams or vapor in dental offices.
Allergic/hypersensitive reactions: Dental materials -- not just amalgam -- can, in rare instances, cause allergic or hypersensitive reactions. Some people have a chronic inflammatory reaction of the gums near a filling. Patch testing for mercury allergy is a difficult procedure and should be carried out by a dermatologist in an allergy clinic.
Development of antibiotic resistance: Anne Summers, a microbiologist at University of Georgia, has found a connection between mercury leached from amalgam and antibiotic resistance, as reported in Environmental Health Perspectives (August, 1996). In her studies with monkeys and human subjects, Summers finds that mercury contributes to populations of mercury-resistant bacteria in the intestines, which is linked to subsequent development of resistance to penicillin, streptomycin and tetracycline.
Still, the National Institute of Dental Research maintains that no other restorative material offers the combined strength, durability, and affordability of amalgam. In 1993 the U.S. Public Health Service released a report which said that dental amalgam should continue to be used, given the absence of scientific proof of a human health hazard. But it also said that the potential for subtle, undetected effects from low-level mercury exposure from dental amalgam cannot be totally disregarded.
Many other countries have considered or already taken steps to eliminate dental amalgam's use. For example, the Federal Public Health Office of Germany recommends against using amalgam in pregnant women, in patients with specific forms of kidney disease and in children under age six. In 1992, the Swedish parliament approved a general plan to phase out mercury from all sources, including amalgam. In 1994 Sweden proposed to cease using amalgam entirely by 1997; a final decision is still pending. Canadian health authorities recommend against amalgam use in pregnant women and in those with impaired kidney function. Studies in Denmark and Sweden suggest that dental clinics appear to be responsible for much of the mercury collected in sludge by water purification plants. This sludge cannot be recycled as fertilizer. In several European countries it is mandatory that dental clinics install a device to separate amalgam from water.
What YOU Can Do: Fillings
- If you are or may be pregnant, try to avoid all unnecessary exposures to questionable agents like amalgam.
- If you or your child needs a filling, talk to your dentist about your options, such as tooth-colored plastic composite materials, cements, porcelain and other ceramics. "For cavities in areas that don't bear a lot of stress -- such as the surface or corners of front teeth -- there are various bonding and adhesive techniques that can be used," says Bruce Scott, D.M.D., a dentist in New York City. "In posterior teeth, tooth-colored materials may not be strong enough, so gold inlays or crowns can be used." Dr. Scott also notes that an amalgam material called "galloy," which substitutes gallium for mercury, has just been developed, and is significantly less expensive than gold inlays or crowns. Like many dentists, Dr. Scott agrees with the American Dental Association and the National Institute of Dental Research that dental amalgam is a safe and cost-effective material.
- Talk to your dentist about what steps he or she takes to protect people and the environment. Mercury is released during the placement and removal of amalgam, but the level of mercury vapor and amalgam particles can be minimized. Dr. Scott sells amalgam waste to a scrap dealer; he believes that, most dentists like himself, now use mercury pre-mixed into a capsule to avoid the possibility of accidental release. Other protection techniques include avoidance of ultrasonic condensing, use of an adequate water vapor spray and high volume suction during drilling or polishing procedures, and the use of a rubber dam.
- Since most people do not have any illness or symptoms from their amalgam fillings, there is no reason to have them removed. Some of the potential risks with amalgam-removal include loss of tooth substance and elevated exposure to mercury during the amalgam-removal period. Plus, there's no guaranteed benefit. Symptoms of chronic low-level mercury poisoning are subtle and non-specific, such as anxiety, depression, and tremors that can be confused with other medical problems. If you suspect that you have symptoms that are amalgam-related, see your doctor first. Rather than remove amalgam fillings, first try to avoid chewing gum and teeth grinding, which can greatly increase the release of mercury (also, a retainer from your dentist to wear at night might help).
What YOU Can Do: Sealants
- Do not have your child's baby teeth coated unless there is a compelling reason to do so.
- Each parent, in consultation with their dentist, must weigh the benefits of dental sealants with the possible risks. It is probably not a good idea to have teeth coatings removed, since this would create more exposure.
- A risk-free option: Brush and floss often and well! One trick: Listen to music while you brush and don't stop until the song is over. Floss for the encore. Preserve those natural ivories.
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