Dental amalgam may be linked to psychological disorders
SILVER SPRING, Md., USA: The use and toxic risk of dental amalgam fillings is a subject of ongoing debate among health care experts. Now, a review conducted by a team of international researchers has provided new evidence that mercury exposure from dental amalgam may cause or contribute to many chronic illnesses, as well as depression, anxiety and suicide.
The researchers looked at studies involving dental health care personnel, among other aspects. This group of professionals is often exposed to mercury vapor when placing amalgam restorations, for example.
In a 2008 study of 41 dental assistants and 64 controls in Norway, dental assistants were found to have significantly higher rates of neurological symptoms, psychosomatic symptoms, problems with memory and concentration, fatigue, and sleep disturbance compared with the controls. Moreover, a study published in 2012 including 600 dentists showed that they purchased significantly more illness-specific prescribed medications for neuropsychological and neurological conditions than did the controls.
The researchers also found a number of studies that demonstrated significant improvement of psychological symptoms after amalgam removal. For instance, in an investigation of 111 patients with symptoms resembling chronic fatigue syndrome, 76 percent of participants reported significant improvement of symptoms five years after their dental amalgam fillings had been removed.
Furthermore, the review showed a connection of amalgam to mood and mental health. A statistically significant correlation was observed between mean urinary mercury levels and anxiety, and many studies on dental health personnel have found associations between mood and exposure to mercury at levels previously thought to be safe.
A post-mortem study published in 2006 established a link between elevated mercury levels and suicide. In this study, the researchers from Italy investigated 18 cadavers, of which eight were suicide cases. They reported that 63 percent of the latter had more than 12 occlusal amalgam surfaces, while this was only the case in 10 percent of the remainder. The researchers concluded that the levels of mercury in the suicide cases were on average about three times higher than in the nonsuicide cases.
"The evidence provided in this review suggests that dental amalgams may be a significant contributing factor in the burden of disease. Furthermore, interactions between Hg and other causes of disease might be more the rule than the exception," the researchers of the current review concluded.
Although high levels of mercury exposure are known to cause serious health complaints, the effects of chronic low-level exposure are not yet fully understood by scientists, primarily owing to a lack of representative research. However, the World Health Organization has warned that exposure to mercury—even small amounts—may cause serious health problems. The organization considers mercury as one of the top ten chemicals or groups of chemicals of major public health concern, as it has been shown to have toxic effects on the nervous, digestive and immune systems, and on the lungs, kidneys, skin and eyes. However, the toxicology of dental amalgam is not generally recognized by physicians or institutions, including the Food and Drug Administration, which considers the restorative material as generally safe. Only a few countries, including Norway and Sweden, have banned dental amalgam. Some countries, such as Germany and Canada, advise against the use of amalgam in children and pregnant women.
The study, titled "Evidence Supporting a Link Between Dental Amalgams and Chronic Illness, Fatigue, Depression, Anxiety, and Suicide," was published in Neuroendocrinology Letters. It was conducted by researchers from various scientific institutions in the U.S. in collaboration with researchers from Norway.
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