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The goal of this study was to investigate the effectiveness of stand-alone modular air purification sys-tems in improving air quality in dental practices, hospital and laboratory environments. As air pollu-tant make-up and concentration may vary significantly in different indoor environments, the air clean-ing technologies utilised should be optimised for the pollutants targeted in a particular environment. Reduction of mercury vapours and formaldehyde were examined because of their importance for indoor air quality in dental practices. In addition, the reduction of particles and microorganisms was investigated as well as the removal of substances which are noticeable due to their strong odours. The air purifiers used in the study were configured to contain the most suitable air cleaning technology for each of the indoor environments. The systems use high-efficiency particulate air (HEPA/ULPA) filters, activated carbon-based filters with and without impregnation and/or activated alumina-based filters with impregnation. The maximum airflow of the systems ranges between 220 and 500 m3/h, depending on the filter configuration. The units were investigated under laboratory and simulated field conditions to determine removal efficiencies for various substances. High removal efficiencies for mercury vapour, formaldehyde, particles and microorganisms could be observed. The elimination of strong odours (orange oil, cinnamon oil and menthol) is difficult, if the source of the odour is not removed. The unit’s effectiveness in dental practices and in hospital treatment rooms will be analysed in follow-up studies including personal bio-monitoring investigations. The data will facilitate the evaluation of the role that optimised air purification systems can play in reducing pollutant exposure of medical personnel and patients.

Studies examining health consequences of the release of mercury from dental amalgams have concluded that there is insufficient mercury released from these restorations to cause a medical problem. Although the mercury vapor generated during removal of amalgams will cause a transient increase in the patient’s mercury level in tissue fluids, biochemical assays have demonstrated that the increase is too small to have a negative influence on organ systems. This is true even when patients have all their amalgams removed in a single session. Nevertheless, over the past decade, the release of mercury from dental amalgam has been frequently blamed for a variety of health complaints. A number of sensationalized media reports regarding the mercury issue have no doubt contributed to the public concern that has been aroused. Consequently, patients may present at the dentist’s office, either self-diagnosed or looking for a cause implicating mercury. In actuality, these patients may have symptoms of either medical problems or psychological disorders such as depression or anxiety. Unfortunately, the incorrect diagnosis may not only mislead, but actually place the patient in a dangerous situation. Two well-controlled studies have indicated that (1) 89% of the patients with self-reported “amalgam illness” had psychogenic disorders, whereas only 6% of the matched-pair manifested symptoms of these psychological disorders; and (2) these alleged “amalgam illness” patients had preneurotic reactive/defensive mechanisms that did not allow them to recognize aggressive and threatening situations which the control group would quickly and readily regard as potentially difficult to manage. Other studies involving psychological assessment seem to confirm that dental therapy (removal of amalgams) for people with alleged “amalgam illness” may, at best, provide a “placebo effect”.

Inflammatory cells in amalgam-associated, oral lichenoid contact lesions (OLL) were studied in 19 patients by immunocytochemistry using monoclonal antibodies. Ten of the patients displayed allergic patch test (PT) reactions to several mercury compounds and nine were negative. The immunocytochemical quantification showed a uniform composition of the inflammatory mononuclear cells in the two study groups. The number of HLA-D/DR-positive dendritic cells (P<0.001) and CD1a-positive Langerhans cells (P=0.035) was significantly lower in the PT-negative than PT-positive patients. HLA-D/DR expression on keratinocytes varied from negative to full thickness staining of the epithelium. HLA-D/DR expression in the full thickness of epithelium (3) or through the basal and spinous cell layers (2) was seen in 5 of 8 PT-positive patients, whereas none of the PT-negative patients had this staining pattern (P=0.045). These patients also showed a good clinical response after amalgam removal. Consequently, OLL may represent a true delayed hypersensitivity reaction with a trans-epithelial route of entrance of the metal haptens released from dental restorative materials.

In 111 women with repeated miscarriages, the urinary excretion of heavy metals was determined in a challenge test with the chelating agent 2,3-dimercaptopropane-1-sulphonic acid in addition to hormonal, chromosomal, immunological and uterine investigations. The heavy metal excretion was correlated to different immunological (natural killer cells, T cell subpopulations) and hormonal (progesterone, oestradiol, prolactin, thyroid stimulating hormone) parameters. We conclude that heavy metals seem to have a negative impact on ovarian as well as on pituitary function. The heavy metal-induced immunological changes may interfere with the physiological adaptation of the immune system to the state of pregnancy with the result of a miscarriage. The observed heavy metal-induced hormonal and immunological changes may be important factors in the pathogenesis of repeated miscarriages.

Before and after treatment scores on the Minnesota Multiphasic Personality Inventory – II (MMPI-II) were compared for 11 manic depression subjects with amalgams removed and for 9 subjects with amalgams who were told they were being given a placebo or sealant. Of the 87 scales, the amalgam removal group improved significantly more in 47 of them. Depression and hypomania scores improved significantly, as did anxiety, anger, schizophrenia, paranoia, and many others. Scores on the Million Clinical Multiaxial Inventory II found the scores in the amalgam removal group improved significantly more in the scales of avoidant, dependent, anitsocial and borderline, compared to the sealant / placebo group. The scores in the categories of Clinical Personality pattern category and severe Personality Pathology category also improved significantly more in the amalgam removal group. All scores of the nine dimensions tested in the Symptom Check List 90 improved significantly more in the group with amalgam removal. They included somatization, obsessive complusive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoia, and psychotism. The amalgam removal group reported a 42% decrease in the number of somatic symptoms in the placebo / sealant group when comparing a before and after health questionnaire.

This study looked at the relationship between myopia and mercury from dental fillings. Hair mercury levels were found to be significantly higher in 25 nonmyopic children compared to 25 myopic children. The researchers hypothesized that if mercury was leaching from the silver dental fillings, then subjects without dental fillings would have a higher degree of myopia and poorer acuity. A study comparing 51 subjects without amalgams confirmed this hypothesis. The non-amalgam group had a 59 percent higher degree of myopia and significantly poorer acuity. Two additional studies also found that subjects without amalgams had a higher degree of myopia. All three studies found that significantly more subjects without amalgams wore glasses for distance when compared to subjects with amalgams. The authors hypothesize that mercury may increase the collagen fibrils of the sclera and thereby retard the progression of myopia.