Study backs amalgam
Top scientists find no link to neurological functions
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Posted March 16, 2005 |
By Mark Berthold Bethesda, Md. — A new study, conducted by leading scientists from highly regarded research and academic institutions, finds no link between amalgam exposure and neurological function.
"Our findings do not support the hypothesis that exposure to amalgam produces adverse, clinically evident neurological effects," concludes a research team led by Albert Kingman, Ph.D., Chief, Biostatistics Core, at the National Institute of Dental and Craniofacial Research, part of the federal National Institutes of Health.
These effects tested, as part of the overall neurological evaluation, include abnormal tremors, coordination, station or gait, strength, sensation and muscle stretch reflexes.
The study, "Amalgam Exposure and Neurological Function," appears in the March issue of NeuroToxicology. It followed 1,663 subjects of the ongoing Air Force Health Study of Vietnam era veterans.
An oral health examination has been part of the standard AFHS medical examination since 1992 because "peripheral neuropathy" is considered to be an important adverse neurological effect of high levels of exposure to elemental mercury.
"Peripheral neuropathy" refers to an abnormality in sensation, such as vibration sensation at the ankle, pinprick sensation at the great toe and/or absence of ankle reflexes.
But as with other neurological effects, the study found no connection of amalgam to any level of peripheral neuropathy.
"We were unable to detect any associations between amalgam exposure and clinical signs of either neuropathy or a diminished sensation of the big toe among adult males — these are standard measures for diagnosing clinical neuropathy," says Dr. Kingman.
"Our study represents another important piece to the research puzzle because of the unique military population tested," Dr. Kingman continues. "Our results should be taken in the context of the larger group of clinical studies that have not found direct evidence linking amalgam exposure to impaired neurological function or peripheral neuropathy."
"The bottom line," says co-researcher James W. Albers, M.D., Ph.D., of the University of Michigan Medical School, "is there was no association between abnormal neurological signs and amalgam exposure. So these findings do not support the hypothesis that amalgam exposure produces clinically evident neurological effects."
The NIDCR-led research was conducted because "concerns regarding the safety of silver-mercury amalgam fillings continue to be raised in the absence of any direct evidence of harm," the study reads. "The widespread population exposure to amalgam mandated that a thorough investigation be conducted of its potential effects on the nervous system."
Dr. Daniel M. Meyer, associate executive director, ADA Division of Science, notes, "Amalgam is a safe dental restorative material. This study, like the recently published report by the independent, nonprofit Life Science Research Office, which extensively reviewed the literature and concluded that amalgam is safe to use in people, adds to the definitive scientific evidence attesting to amalgam's demonstrated track record of safety."
The LSRO report's executive summary can be downloaded at no cost by visiting "www.lsro.org", click on "Review of Dental Amalgams." To obtain the full text, call the LSRO bookstore at 1-301-634-7030.
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