Dental amalgam: designs for research in human populations
Article Abstract:
Although the possible health hazards of dental amalgam (material used in fillings that contains mercury) have been debated for more than a century, no firm scientific evidence has been uncovered that definitely shows amalgam is toxic. The types of studies that could be performed to learn more about this issue are described in this article. Humans take in mercury in the diet (primarily from fish) and from dental amalgam. Elemental mercury vapor is released from amalgam and inhaled; once in the lungs, it is distributed throughout the body. Mercury ions are formed and can accumulate in tissues; the kidney and nervous system are particularly vulnerable. But mercury accumulation reverses itself, and the substance is excreted in urine. Toxicity occurs when too much accumulates, which is indicated by muscle tremor, poor finger coordination, jerky movements, insomnia, appetite loss, and diarrhea. The condition is difficult to diagnose in mild cases. The four main types of experimental studies that could be pursued to learn more about mercury toxicity from amalgam are cross-sectional studies, case-control studies, cohort studies, and intervention studies. Cross-sectional studies look for correlations between an outcome measure (such as the concentration of mercury in urine) and an exposure measure (the number of amalgam fillings). Case-control studies compare the number of amalgams in people who display a symptom that is associated with mercury toxicity (cases), with the number of amalgams in people without that symptom (controls). Cohort studies follow a selected group of people with known levels of exposure over time to see which ones develop symptoms. Finally, intervention studies, the strongest experimental design, select subjects with predetermined levels of mercury exposure and evaluate their responses. Good research concerning amalgams and health should be interdisciplinary and collaborative, and should make the best use of existing data. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journal of the American Dental Association
Subject: Health
ISSN: 0002-8177
Year: 1991
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The plaque fighters: choosing a weapon
Article Abstract:
Improved toothbrush designs may aid in the removal of dental plaque. Numerous toothbrushes with new head shapes and angles, bristle lengths and designs have been introduced since the 1970s. The main purpose of these innovations was to make up for the inadequacies of the user's brushing technique. One area of particular importance is the interdental space, especially for individuals who do not floss or use other interdental aids. A new generation of electric toothbrushes was introduced in the 1980s. The main feature of these toothbrushes was an oscillating, counter-rotational motion. These brushes may be more effective than manual brushes in the removal of dental plaque and the prevention of gingivitis, or gum disease. Many new manual toothbrushes have also been introduced. No significant difference may exist among the different designs and their effectiveness in the removal of plaque or the prevention of gingivitis.
Publication Name: Journal of the American Dental Association
Subject: Health
ISSN: 0002-8177
Year: 1993
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