Dear Doctor Column, July 24, 2006
No Need to Replace Silver Fillings
Question:
I’ve heard the mercury in silver fillings is linked to certain serious health problems, including Alzheimer disease and autism. My children and I have silver fillings — should we have them replaced?
Answer:
For more than 150 years, dentists have used dental amalgam, or silver fillings, to restore decayed and fractured teeth. Amalgam is a mixture of silver, copper, and tin, which, when combined with mercury, solidifies into a hard, durable, and safe substance. Despite a long track record of effectiveness and safety, a survey by the American Dental Association (ADA) indicates 1 in 4 people have heard that silver fillings are “bad for you” or could cause health problems. Major US and international health agencies, including the National Institutes of Health, the Centers for Disease Control and Prevention, the US Public Health Service, and the World Health Organization, continue to support the use of dental amalgam, noting there is no reliable scientific evidence connecting dental amalgam to any medical condition.
Two recent independent clinical trials funded by the National Institute of Dental and Craniofacial Research confirmed the safety of amalgam fillings in children. Both studies, one conducted in Portugal and the other in the United States, were randomized controlled trials ─ considered the most accurate form of medical investigation. Results, reported in the April 19, 2006 issue of the Journal of the American Medical Association, found that children whose cavities were filled with dental amalgam had no adverse health effects. Investigators found that 5 to 7 years after receiving the amalgam fillings, children had no detectable loss of intelligence, nerve conduction, or kidney function compared with a control group of children who received tooth-colored, or composite, fillings. Study authors concluded dental amalgam should remain an important treatment option for dental care. These studies support a large body of existing scientific evidence showing the tiny amount of mercury released by dental amalgam as people eat and drink does not pose any health risks.
For many years, scientists thought people’s direct exposure to mercury in fillings occurred only while the dentist was placing amalgam in the tooth. In the late 1970s, investigators developed more sophisticated measurement devices, and scientists were able to show dental amalgam continuously releases mercury vapor into the mouth, where it is absorbed by the body. This raised the concerns that persist today.
Mercury is a toxic substance and high levels of exposure, which are usually industrial, can cause irritability, memory loss, tremors, weakness, poor physical coordination, insomnia, kidney failure, and excessive weight loss. Yet the amount of mercury released by fillings is miniscule, and comprises only a small proportion of people’s daily mercury exposure. According to the ADA, people get more daily mercury exposure from certain foods and medications, water, and air than from the tiny amounts of mercury vapor generated from amalgam fillings. The Environmental Protection Agency notes that in the United States, people’s primary exposure to mercury comes from eating certain fish and shellfish containing methylmercury.
Dentists have developed a number of new materials for dental fillings, including tooth-colored composites and ceramics, but many of these are more expensive, may take more time to place, and are sometimes less durable than amalgam. Amalgam’s affordability, strength, and safety have made it a mainstay of dental care. Its durability makes it particularly useful for fillings in back teeth, which have to withstand greater chewing forces. The biggest drawback to amalgam fillings is their silver color, which is obviously not natural, and short-term sensitivity to hot and cold foods and beverages. A very small number of people are allergic to amalgam fillings ─ about 1% of the population.
So what’s fueling the controversy about dental amalgam? Sensational stories in the media and circulating on the internet continue to feed people’s fears about mercury poisoning, linking mercury exposure from amalgam to a variety of diseases and symptoms, including autism, Alzheimer disease, multiple sclerosis, anxiety, headaches, and insomnia.
Major US health agencies have extensively evaluated amalgam time and time again and declared it safe and effective. Removing an amalgam filling may weaken the tooth, and none of these organizations recommends replacing amalgam fillings with another material because of concerns surrounding mercury exposure. Additionally, the Alzheimer’s Association, the American Academy of Pediatrics, the Autism Society of America, the American Cancer Society, and the National Multiple Sclerosis Society endorse the continued use of amalgam as a safe, strong, inexpensive material for dental restorations.
Deciding which type of filling you need is a decision best made by you and your dentist. To learn more about the different types of dental fillings available, the ADA offers a patient brochure, “Restoring Your Smile: Dental Filling Choices,” on the ADA’s Web site at www.ada.org/public/topics/fillings.asp.