Study Reveals No Relationship Between Dental Amalgam and Alzheimer's Disease

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Definitive Study Reveals No Relationship Between Dental Amalgam and Alzheimer's Disease

CHICAGO -- Dental amalgam (silver fillings) and its mercury component are not factors in the development of Alzheimer's disease, concluded researchers in a definitive study published in the February 1999 issue of The Journal of The American Dental Association. "This study demonstrates that dental amalgam is not a major public health risk factor for Alzheimer's disease," concluded Stanley R. Saxe, D.M.D. and lead-study author. "We found no association between brain mercury levels and dental amalgam, and no significant difference in brain mercury levels between subjects with Alzheimer's and the control subjects without the disease." Dr. Saxe is the recently retired professor of periodontics and geriatric dentistry, and director of the Geriatric Oral Health Program, College of Dentistry, University of Kentucky at Lexington.

This is the first, thorough clinical pathological correlative study of humans to show that mercury in dental amalgam restorations does not appear to be a neurotoxic factor in the development of Alzheimer's disease, Dr. Saxe said. "We designed this study to address the limitations of earlier studies, particularly the lack of information about past dental amalgam restoration experiences," explained Dr. Saxe. Dental amalgam is used extensively in tooth fillings and according to a 1995 survey, up to 76 percent of dentists used it as their primary restoration material. Alzheimer's disease is a major health problem for older adults, affecting up to four million Americans.

Trace levels of many metal elements, including mercury, have been reported to be imbalanced in patients with the disease. It also has been speculated that the imbalance may play a role in the development of Alzheimer's disease.

"We conducted an investigation to determine the relationship between brain mercury levels, Alzheimer's disease and dental amalgam exposure," Dr. Saxe said.

In the investigation, the authors studied 68 subjects with Alzheimer's disease and 33 control subjects without the disease to determine mercury levels in various brain regions. The study included only subjects who met the strict criteria for Alzheimer's disease, and who had no confounding disorders such as strokes, cerebral oxygen deficiency or other disorders that could cause dementia.

Evaluation also included determining the number and location of existing teeth, plus assessing existing amalgam restorations and past amalgam experience. Dental histories of each subject's 32 teeth were completed and information was obtained on non-dental exposure to mercury.

The authors measured mercury levels in multiple brain regions and performed full nervous system disease evaluations to confirm the normal status of the brain or the presence of Alzheimer's disease.

"Our results do not support the hypothesis that dental amalgam is a major contributor to brain mercury levels and that mercury is a factor in developing Alzheimer's disease," the authors concluded.

"This study demonstrates that dental amalgam is not a public health risk factor for Alzheimer's disease." "The World Health Organization, FDI World Dental Federation and the American Dental Association (ADA) all support the continued use of dental amalgam as a safe, durable and cost-effective material to restore teeth," said Gary C. Armitage, DDS, chairperson of ADA's Council on Scientific Affairs.

Additionally, the U.S. Public Health Service issued a report in 1993 stating there is no health reason not to use amalgam, except in the extremely rare case of the patient who is allergic to a component of amalgam, explained Dr. Armitage. This supports the findings of the Food and Drug Administration, the National Institutes of Health Technology Assessment Conference and the National Institute of Dental and Craniofacial Research, that dental amalgam is a safe and effective restorative material. For more information about amalgam and oral health care, visit ADA's web site at www.ada.org.

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