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In a very recent Swedish study, Prof. Bratel and coworkers from the University of Göteborg have focused on a group of 50 patients who complained of common disturbances such as anxiety, asthenia and depression, which they claimed to be related to amalgam restorations. The study compared them with a control group of patients who had been matched as for age, sex, place of residence and oral pathology. Both groups of patients underwent blood and urine analysis and had a psychiatric examination. In agreement with a previous study by Hampf, the research, which appeared in 1997 in the European Journal of Oral Science, showed that the levels of Hg were identical in the two groups and that 70% of the complaining patients had been affected by some psychiatric disorder. In our opinion, it is of the uppermost importance that people be correctly informed on the position taken by the international scientific community and the leading health care agencies with respect to the potential risk of amalgam. In the US, the Assistant Secretary for Health has established in 1991 a research committee with the aim of carefully reviewing nearly 500 scientific publications on amalgam. The study, which appeared in 1995, failed to show any harmfulness for the amalgam fillings. Following the advice of the General Surgeon and the Center for Disease Control and Prevention of the Food and Drug Administration, the US Public Health Service has recently published an article in a magazine with a very high circulation. The purpose was to clarify the issue and reassure the American people, who had been alarmed by the many news reports on the amalgam risk. In Switzerland, Chairmen from the four Dental Departments at Universities of Berne, Basel, Geneva and Zurich replied to the alleged charges of amalgam-induced damages -which appeared on newspapers and non-scientific journals- with a review article. Accordingly, amalgam was judged as a safe and effective material for posterior tooth filling, with the only exception of allergic patients. Prof. Wirz, head of the Division of Dental Economics at the University of Basel, published in 1995 an article in defense of amalgam, which received much consideration. At two Meetings of the Federation Dentaire Internationale held in 1994 in Vancouver and Budapest, the amalgam was acquitted on the charge of toxicity and was judged as a valid, cheap and still unreplaceable material. In a 1995 joint statement from the World Health Organization through two of its agencies -the Oral Health Programme and the Office for Global and Integrated Environmental Health-, and from the FDA, amalgam fillings were considered to be safe and inexpensive, although their color was different from that of natural teeth. For environmental reasons, the document also reported, -there was -or would have been in the future- some limitation to the use of amalgam; unfortunately, such restrictions had been misinterpreted by the mass media, and this had caused unjustified fears in the public opinion and a rising demand for substitution of the restorations. Ever since the first environmentalist protests against the use of amalgam, a Research Center was created in Germany by the University Departments of Münster and Erlangen. After reviewing several scientific papers and following hundreds of patients, including 200 pregnant women, the center concluded that: (i) no danger from amalgam had been found in both the general population and the newborns; (ii) high plasma levels of Hg had been found as a consequence of elevated fish consumption. After careful studies, the Swedish Medical Research Council concluded that all restoration materials currently in use, including amalgam and composite resins, are safe and effective. Nevertheless the Swedish government, through the Department of Environment, recently issued a series of rules to limit the use of amalgam for filling purposes. The main argument was based on an ecological ground, as it was estimated that between 40 and 60 tons of amalgam are carried in the mouth of Swedish people. It was feared that, as a consequence of crematory habits, Hg would be massively released in the environment. In Sweden alone, nearly 300 Kg of Hg are estimated to be dispersed in the atmosphere, and between 200 and 400 Kg in the water mains, every year. A good substitute for amalgam, in terms of optimal marginal sealing, easy handling and low cost, has yet to be found. Although gold or ceramics are highly valuable as amalgam substitutes, they require the work of a dental technician and more complex procedures, resulting in a 5-6 times higher cost. Composite resins have been the object of a great number of studies by the research industry. The resins are able to bind firmly to the dental enamel; moreover, since they have the same color of teeth, restorations become invisible and are therefore greatly appreciated by patients. However, the long-term behavior of composite resins is largely unknown. The marginal sealing might become less efficient because of an excess polymerization-dependent shrinkage of the resin. For these reasons, composite resins cannot substitute the amalgam in every clinical condition; moreover, due to the longer time and care needed, restoration costs for resins are far higher than for amalgam. There is no question about the fact that the international dentist community has been strongly reducing the use of amalgam for filling carious teeth; the main reason, however, has been an aesthetic demand from patients rather than a toxicological need. Not unexpectedly, most colleagues from all over the world have kept using amalgam in their own -or their offspring’s- mouth, whenever needed. As reported in the literature, a certain number of patophobic or easily influenced patients still prefer to have restorations with materials other than amalgam, even after receiving all possible informations. Their demands should be satisfied as long as this decision may have a placebo effect; however, these patients should be discouraged from having their still perfect amalgam restorations substituted by other materials. As a useful reminder to the reader: the best filling is the one that has never been applied; the most effective therapy is prevention. Bibliografy
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