High mercury emissions from dental clinics despite amalgam separators.

Mercury (Hg) as amalgam has been used as a dental filling material for more than 150 years. Thereby, dentists and their patients have been directly exposed to Hg, and the public and the environment indirectly exposed via Hg emissions from incinerators and Hg in waste water from households and dental clinics. Due to the toxic properties of Hg and bioaccumulation in biota of Hg emitted via dental clinic waste water, amalgam separators were introduced in Sweden in the 1980s. Although these amalgam separators in the certification process are required to remove at least 95% of incoming Hg in a standardized laboratory test, their efficiency in practical use has not been properly investigated. Here we present actual Hg emissions via waste water from 12 dental clinics equipped with the same type of amalgam separator based on sedimentation. All waste water was collected for four consecutive working days, initially at ordinary operating conditions and a second time after a thorough revision and cleaning of the discharge system. The results indicate that mercury emissions from dental clinics can be reduced by an improved design of the discharge system, a sensible use of high pressure water cleaning, and regular maintenance, including replacement of amalgam separators and filters at certain intervals. The study also indicates that banning Hg in dentistry is the one long-term way to stop Hg emissions from dental amalgam.

Mercury recovery in situ of four different dental amalgam separators.

Amalgam separators are used to physically remove dental amalgam from waste water in dental clinics. They are thereby supposed to reduce mercury (Hg) emissions to the municipal waste water system to acceptable levels. We here present results from a comparative study in situ of three amalgam separators available on the market, all with a claimed efficiency of 99% according to Danish and ISO protocols, and using sedimentation as the principle of separation. We also present corresponding data for an investigational prototype of an improved separator. The obtained efficiency of the three commercial separators is far below what is stated by the manufacturer and by authorities assumed to be the efficiency in clinical conditions. They reduced Hg emissions by 79 - 91%, leaving an average Hg content in outgoing waste water of 1.5 mg L(-1). However, the prototype separator participating in this study retained 99.9% of the waste water Hg emissions, leaving an average Hg content in outgoing waste water of 0.004 mg L(-1). Physical restrictions prohibit sedimentary type separators to recover the Hg fractions causing the largest damages in wastewater treatment plants. This fraction is not considered in the ISO protocol for testing amalgam separators, which therefore needs to be revised. Abolishing the use of dental amalgam and cleaning the tubing systems is the most efficient long-term solution to reduce Hg emissions from dental clinics. Until then, Hg emissions originating from placing, polishing or removing existing amalgam fillings, should be counteracted by the use of low-emission amalgam separators, already on the market or presently being developed for use alone or together with sedimentary type amalgam separators.

Metal-specific lymphocyte reactivity is downregulated after dental metal replacement.

OBJECTIVES: This study was done to evaluate the results and clinical relevance of an optimized lymphocyte proliferation test, MELISA, for metal-induced inflammation in patients with CFS-like symptoms. The treatment of patients consisted of the replacement of incompatible dental materials (RID) together with supportive anti-oxidant therapy. DESIGN OF THE STUDY: 513 patients were tested by MELISA at the beginning of the study. Out of this group, 248 patients were available for follow-up MELISA after RID. METHODS: In MELISA, lymphocytes are isolated from the blood and cultivated with different metal salts in tissue culture medium containing 10% inactivated human AB+ serum or autologous serum. After 5 days, the presence of metal-reactive lymphocytes are measured by isotope labelling of newly formed DNA in growing lymphoblasts and evaluated by calculating the Stimulation Index. RESULTS: Nickel was the most common sensitizer, followed by inorganic mercury, thimerosal, lead, cadmium, palladium and gold. After RID treatment, a decrease of metal-specific lymphocyte responses in patients who reacted to metals at the beginning of the study could be observed. The cultivation of lymphocytes in autologous and homologous serum did not significantly affect the results. Simultaneous, the health status of patients improved as well. CONCLUSIONS: Replacement of incompatible dental materials resulted in down-regulation of metal-induced lymphocyte sensitivity in vitro, as well as in the improvement of health status of majority of patients with unspecific CFS-like symptoms.

Decrease of trace elements in erythrocytes and plasma after removal of dental amalgam and other metal alloys.

The objective of this study was to determine the concentration changes of 13 elements in erythrocytes and plasma after the removal of dental amalgam and other metal alloys. Blood samples from 250 patients were collected, separated into erythrocytes and plasma, and analyzed by inductively coupled plasma-mass spectrometry. The 250 patients were divided into 3 groups (Negative, Zero, and Positive) depending on their estimation of quality of life in an earlier study. Magnesium in plasma, selenium and mercury in plasma, and erythrocytes showed decreased concentrations after amalgam removal in all groups (p < 0.05). Titanium in plasma, copper in plasma, and erythrocytes and zinc in plasma exhibited decreased concentrations after amalgam removal in the Negative and Positive groups (p < 0.05). Silver in plasma and gold in erythrocytes decreased in the Zero and Positive groups after amalgam removal (p < 0.05). Copper in erythrocytes and silver and gold in plasma showed higher concentrations after amalgam removal in the Negative compared to the Positive group (p < 0.05), suggesting that patients in the Negative group excrete metals slowly. Moreover, the cobalt levels in plasma were lowest in the Negative group and only this group showed a significant increase in vitamin B12 levels in blood after amalgam removal.

Removal of dental amalgam and other metal alloys supported by antioxidant therapy alleviates symptoms and improves quality of life in patients with amalgam-associated ill health.

OBJECTIVES: The purpose of this study was to evaluate treatment of patients suffering from chronic ill health with a multitude of symptoms associated with metal exposure from dental amalgam and other metal alloys. SETTING AND DESIGN: We included 796 patients in a retrospective study using a questionnaire about symptom changes, changes in quality of life as a consequence of treatment and assessment of care taking. METHODS: Treatment of the patients by removal of offending dental metals and concomitant antioxidant therapy was implemented according to the Uppsala model based on a close co-operation between physicians and dentists. RESULTS: More than 70% of the responders, remaining after exclusion of those who had not begun or completed removal, reported substantial recovery and increased quality of life. Comparison with similar studies showed accordance of the main results. Plasma concentrations of mercury before and after treatment supported the metal exposure to be causative for the ill health. MAIN FINDINGS: Treatment according to the Uppsala model proved to be adequate for more than 70% of the patients. Patients with a high probability to respond successfully to current therapy might be detected by symptom profiles before treatment. CONCLUSIONS: The hypothesis that metal exposure from dental amalgam can cause ill health in a susceptible part of the exposed population was supported. Further research is warranted to develop laboratory tests to support identification of the group of patients responding to current therapy as well as to find out causes of problems in the group with no or negative results.

Metal-specific lymphocytes: biomarkers of sensitivity in man.

Many patients attribute their health problems to amalgam and other dental metals. In genetically susceptible indviduals, mercury and gold may function as haptens and elicit allergic and autoimmune reactions. The frequency of metal-induced lymphocyte responses was examined in 3,162 patients in three European laboratories using MELISA(R), an optimized lymphocyte proliferation test. The patients suffered from local and systemic symptoms attributed to dental restorations. The effect of dental metal removal was studied in 111 patients with metal hypersensitivity and symptoms resembling Chronic Fatigue Syndrome (CFS). After consultation with a dentist the patients decided to replace their metal restorations with non-metallic materials. The changes in health and in vitro lymphocyte reactivity were studied by inquiries and follow-up MELISA(R). Lymphocyte reactivity was also analyzed in 116 healthy subjects with no complaints of metal allergy. A significant number of patients had metal-specific lymphocytes in the blood. Nickel was the most common sensitizer, followed by inorganic mercury, gold, phenylmercury, cadmium and palladium. As compared to lymphocyte responses in healthy subjects, the CFS group had significantly increased responses to several metals, especially to inorganic mercury, phenylmercury and gold. Following dental metal removal, 83 patients (76%) reported long-term health improvement. Twenty-four patients (22%) reported unchanged health and two (2%) reported worsening of symptoms. Following dental metal replacement, the lymphocyte reactivity to metals decreased as well. We propose that an inflammatory process induced by metals may modulate the hypothalamic-pituitary-adrenal axis (HPA axis) and trigger multiple non-specific symptoms characterizing CFS and other chronic conditions like myalgic encephalitis (ME) and multiple chemical sensitivity (MCS).