Comprehensive medical examination of a group of patients with alleged adverse effects from dental amalgams

Minor changes in serum levels of cytokines after removal of amalgam restorations

Dental amalgam restorations release mercury and silver which is absorbed and distributed in the body. Animal studies have shown that both elements may interfere with the host by activation of the immune system in genetically susceptible strains at exposure levels relevant to those from dental amalgam restorations. The aim of this study was to test the hypothesis of no change over time in concentrations of a number of immune mediators in serum after removal of all dental amalgam restorations in patients with health complaints attributed to their amalgam restorations and compare with a healthy reference group. Twenty patients previously examined at a specialty unit for health complaints attributed to dental materials were included in a clinical trial and had all amalgam restorations replaced with other dental restorative materials. Serum samples were collected before amalgam removal and 3 and 12 months after the removal was finished. Twenty blood donors matched for age and gender were used as comparison group. A fluorescent bead-based (Luminex) immunoassay kit was used to measure cytokines, chemokines and growth factors in serum. At baseline, the patient group had slightly higher values for GM-CSF, IL-6, IL-2R, IFN-alpha, IL-7, and IL-12p40/p70 compared with the reference group. After amalgam removal a decrease towards the median value of the reference group was found for GM-CSF, IL-8, and IL-7. In conclusion, removal of all dental amalgam restorations and replacement with other dental restorative materials was associated with decreased concentrations of Th1-type proinflammatory markers in serum.

The Release of Mercury from Amalgam Restorations and Its Health Effects: A Review

Amalgam remains an important restorative material in dentistry. Because of continuing controversy concerning the material's safety and environmental friendliness, dentists should remain current in their knowledge of the effect of mercury and its release from amalgam. This will enable dentists to provide accurate, evidence-based information to their patients.

The safety of dental amalgam in children

The safety of mercury-containing dental amalgam has been hotly debated for well over a century. Dental exposures from mercury have been suggested as the cause of numerous diseases including multiple sclerosis, autism and many others. Known health effects of mercury exposure include CNS and renal damage. However, these effects have only been shown at occupational or higher levels of exposure, and have not been conclusively shown to be present at levels of mercury exposure consistent with that from dental amalgam fillings. The use of mercury amalgam fillings remains a state-of-the-art treatment for dental caries throughout the world. Although there have been a small number of peer-reviewed reports examining the health effects of dental mercury in children, only very recently have the only randomised, controlled clinical trials (two) of the safety of mercury amalgam been published. The purpose of this review is to discuss the scientific evidence on the safety of the use of mercury-containing dental amalgam as a treatment for dental caries.

Reporting on adverse reactions to dental materials--intraoral observations at a clinical follow-up

OBJECTIVES

A national reporting system designed to monitor adverse reactions to dental materials was established in Norway in 1993. The activities have also included clinical examination of patients with suspected reactions to dental materials. The ongoing activities are coordinated by the Dental Biomaterials Adverse Reaction Unit at the University of Bergen. The reporting procedure is based on voluntary spontaneous reporting by dentists and physicians. The reports could be based on subjective symptoms or objective findings, or both. The aim of the present study was to compare reported objective intraoral findings with those found during examination at the unit.

METHODS

Reported reactions were compared with clinical findings obtained following dental and medical examination at the unit. From 1993 to 1999, a total of 899 reports were received while 253 patients were referred and examined at the unit.

RESULTS

The reports on patients who were examined at the unit involved mainly reactions related to amalgam fillings (84%), metals in fixed dentures (11%), resin-based materials and cements (4%), materials used in removable dentures (2%), and endodontic materials (2%). Edema, lichenoid reactions, ulcers/vesicles, erythema, and atrophy were found in 80 patients during the examination at the unit. For 35 of these patients, the intraoral findings at the unit were also given in the reports. For another 45 patients, objective intraoral signs of reactions were found upon examination at the unit, but these findings had not been reported.

CONCLUSION

A spontaneous reporting system is a cost-effective method for monitoring intraoral reactions associated with dental materials. Considering the increasing number and complexity of these materials, there appears to be a need for continuous validation of reports by a speciality unit. In order to receive more accurate information about the adverse reactions, it would be advisable that the reporting forms include more detailed guidance regarding signs of reactions that practitioners should be on the look out for and consider.

In vitro lymphoproliferative assays with HgCl2 cannot identify patients with systemic symptoms attributed to dental amalgam

Dental amalgam is suspected, by some exposed individuals, to cause various systemic psychological, sensory, and neurological symptoms. Since not all amalgam-bearers experience such reactions, an individual characteristic--for example, a susceptible immune system--might explain these conditions. In vitro lymphocyte proliferation is a valuable tool in the diagnosis of allergy. With HgCl2 as the antigen, however, the test is hampered, because Hg2+ can cause unspecific lymphocyte proliferation, optimal at 1.4 to 9.5 micrograms HgCl2/mL. Recently, the use of suboptimal HgCl2 concentrations (< or = 0.5 microgram/mL) has been suggested to circumvent these problems. The main aim of this study was to investigate whether patients with systemic symptoms alleged to result from the presence of dental amalgam differ from healthy controls, with reference to in vitro lymphoproliferative responses to HgCl2 < or = 0.5 microgram/mL. Three different test protocols--lymphocyte transformation test (LTT) in micro- and macro-cultures, and the memory lymphocyte immunostimulation assay (MELISA)--were used. Other immune parameters--such as a standard patch test for dental materials, the number of T- and B-lymphocytes, monocytes, granulocytes, and NK cells in peripheral blood, allergic symptoms, and predisposition--were also investigated. Twenty-three amalgam patients, 30 healthy blood donors with amalgam, ten healthy subjects without amalgam, and nine patients with oral lichen planus (OLP) adjacent to dental amalgam and a positive patch test to Hg0 were tested. None of the investigated immune parameters revealed any significant differences between amalgam patients and controls. The sensitivity of in vitro lymphocyte proliferation ranged from 33 to 67%, with the OLP patients as a positive control group, and the specificity from 0 to 70% for healthy controls with a negative patch test to Hg0. Thus, despite the use of HgCl2 < or = 0.5 microgram/mL, a high frequency of positive results was obtained among healthy subjects with or without dental amalgam. Consequently, in vitro lymphocyte proliferation with HgCl2 cannot be used as an objective marker for mercury allergy in dental amalgam-bearers.

Dental amalgam: update on safety concerns. ADA council on Scientific Affairs

This report of the Council on Scientific Affairs reviews and discusses recent studies concerning the safety of dental amalgam, with an emphasis on studies that have been published since the 1993 review of dental amalgam by the U.S. Public Health Service Committee to Coordinate Environmental Health and Related Programs. The Council concludes that, based on currently available scientific information, amalgam continues to be a safe and effective restorative material.

Acute glomerulonephritis, Henoch-Schönlein purpura and dental amalgam in Swedish children: a case-control study

The issue of adverse health effects from dental amalgam and the concurrent low-dose exposure to inorganic mercury have been scrutinized by several Swedish expert groups during the past years. Only rarely have amalgam fillings in children been related to health effects. Experimental studies in genetically disposed animals have shown that low doses of inorganic mercury can induce autoimmune glomerulonephritis. The present case-control study included 31 children with acute glomerulonephritis and 33 with Henoch-Schönlein purpura retrieved from an in-patient register for the period 1973-1992 at the county hospital in Halmstad, Sweden. The median age was 10 and 9 years, respectively, for the two diagnostic groups. Dental clinics reported amalgam burden of the patients during the year before the date of diagnosis. Corresponding data were obtained for three randomly selected controls for each case, drawn from the case records of the same dental clinics, with matching for age and sex. Odds ratios (95% confidence interval) were 1.42 (0.49, 4.11) for Henoch-Schönlein purpura, 0.59 (0.25, 1.38) for acute glomerulonephritis and 0.84 (0.40, 1.75) for both diseases combined. The results of this study did not indicate increased disease risk in relation to amalgam burden.

Function of the rat salivary glands after exposure to inorganic mercury

In spite of many studies on the toxicity of mercury, very little is known about the effects of mercury on the function of exocrine glands. In the present paper selected functions of Sprague-Dawley rat salivary glands were studied after the exposure of the animals to inorganic mercury at two different doses; 3.25 mg/kg body weight given during 25 days and 7.0 mg/kg body weight given during 27 days. The function of the salivary glands was estimated by saliva secretion rate, secretion of electrolytes, proteins and biosynthesis of glycoproteins. The function was compared between mercury exposed rats and age and sex matched control rats that were given injections with equal volumes of 0.154 mol/l NaCl on the same time schedule. In the present study we report that no significant effect on saliva secretion rate, concentrations of salivary constituents or biosynthesis of glycoproteins in the salivary glands could be observed in rats as a result of mercury exposure at two levels that gave 30 or 60 times higher serum mercury concentrations than in the majority of the Swedish population.

Toxicological and neuropsychological findings in patients presenting to an environmental toxicology service

Patients presenting to an environmental toxicology service are frequently convinced that their multiple symptoms are caused by exposure to environmental toxicants. In order to evaluate the patients' hypotheses, 120 consecutive patients referred by health care providers to the environmental toxicology service for various symptoms were included in an open prospective study. The basic diagnostic procedure included an environmental toxicology questionnaire, psychological tests, a 45 minute interview, a physical examination and standard biomonitoring for cadmium, mercury, lead, lindane, hexachlorobenzene, DDT, DDE, DDD, and pentachlorophenol and a salivary test for mercury released from amalgam. Allergic disease was found in 42 patients. Nineteen of the 42 patients also had psychosomatic disorders. An unusually high release of mercury from amalgam fillings in the saliva test was found in six patients. An environmental toxic exposure was demonstrated in 19 patients (4 lead, 8 DDE, 6 mercury--most likely from broken thermometers, 1 neurotoxic alkyl naphtol derivatives). Ten of the 19 patients had psychosomatic disorders and six had medical/neurological disorders. Only two patients had symptoms attributable to environmental exposure alone. Rather classical psychosomatic disorders were diagnosed in 83 patients. Of the 37 patients without identifiable neuropsychological dysfunction, 18 had allergic disorders and 12 had other medical diagnoses. The diagnosis of a toxic environmental exposure should be performed in an integrated diagnostic approach covering environmental toxicology and medicine as well as psychosomatic medicine.