Exposure to Dental Filling Materials and the Risk of Dementia: A Population-Based Nested Case Control Study in Taiwan.

When studying the range of toxic substances triggering dementia, special attention should be paid to the materials used in dental practice, particularly to dental fillings containing amalgam. This necessitated conducting large-scale epidemiologic studies. The aim of our research was to determine the risk factors for developing dementia when filling materials containing amalgam are used in dental practice. In order to achieve the set goals, the following tasks were undertaken: (1) The social and demographic characteristics of the examined patients were studied; (2) the spectrum of concomitant somatic diseases was determined in patients of different gender and age; and (3) the relationship between dementia incidence and the volume of dental filling material containing amalgam was identified in patients with different somatic diseases. In general, the research conducted did not reveal any direct relationship between the development of dementia and the volume of filling material containing amalgam. However, among the people with dementia, there were persons for whom its progression was accelerated in cases where a large volume of dental filling material containing amalgam was present.

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.

Symptoms of intoxication in dentists associated with exposure to low levels of mercury.

The present study examined the effects of occupational exposure of a group of dentists to low levels of mercury. The study population consisted of 106 dentists and 94 general practitioners (referent group), from private and public clinics in Shiraz city. Subjects were requested to complete a questionnaire on demographic variables, suspicious symptoms of intoxication and work practices. Additionally, atmospheric and urinary concentrations of mercury were measured by Atomic Absorption Spectroscopy technique. The data were analysed by χ(2) test, independent sample t-test and multivariate logistic regression analysis, where applicable. Both groups were similar as far as most demographic and socioeconomic variables, but age and number of personal amalgam fillings, were concerned. Median of atmospheric concentration of mercury was found to be 3.35 µg/m(3). Likewise, the urinary concentration of mercury in dentists was estimated to be 3.16 µg/g creatinine. This value was significantly higher than that of the referent group. Similarly, analysis of the data revealed that neuropsychological, muscular, respiratory, cardiovascular and dermal symptoms were more prevalent in dentists. Our findings indicate that occupational exposure of dentists to mercury, even at low levels, is associated with a significant increase in the prevalence of symptoms of intoxication.

Historical exposure to mercury among Norwegian dental personnel.

OBJECTIVES: Due to public concern in Scandinavian countries about the health situation of dental nurses, the Norwegian Ministry of Labor and Social Inclusion initiated a project to look at previous exposure to metallic mercury and its possible effects on dental personnel. The aims of this part of the study were to: (i) describe Norwegian dental personnel's exposure to mercury during the last 50 years, (ii) develop a model for scoring that reflects the cumulative exposure on an individual basis, and (iii) relate the calculated score to earlier measured levels of mercury in urine. METHODS: We obtained lists of previous and current dental employees in both the private and public sector and mailed them a questionnaire concerning their working conditions. We received a response from 655 dental nurses and 452 dentists. We also obtained urine mercury levels measured between 1970-1990 for 143 (22%) of the dental nurses and 130 (29%) of the dentists. RESULTS: The results revealed a widespread exposure to mercury in both the individual exposure score and the measured mercury values in urine. For most respondents, however, the level of exposure to mercury seemed to be low. The use of copper amalgam, which is heated before it is applied, is of particular concern as a significant source of mercury exposure in dental personnel. CONCLUSION: It seems evident that the exposure to mercury among dental personnel varies substantially; this is important to take into account when making exposure assessments for this group of workers.

Fish consumption, methylmercury and child neurodevelopment.

PURPOSE OF REVIEW: To summarize recent evidence regarding associations of early life exposure to mercury from maternal fish consumption during pregnancy, thimerosal in vaccines and dental amalgam with child neurodevelopment. RECENT FINDINGS: Recent publications have built upon previous evidence demonstrating mild detrimental neurocognitive effects from prenatal methylmercury exposure from maternal fish consumption during pregnancy. New studies examining the effects of prenatal fish consumption as well as methylmercury suggest there are benefits from prenatal fish consumption, but also that consumption of fish high in mercury should be avoided. Future studies incorporating information on both the methylmercury and the docosahexaenoic acid contained within fish will help to refine recommendations to optimize outcomes for mothers and children. Additional recent studies have supported the safety of vaccines containing thimerosal and of dental amalgam for repair of dental caries in children. SUMMARY: Exposure to mercury may harm child development. Interventions intended to reduce exposure to low levels of mercury in early life must, however, be carefully evaluated in consideration of the potential attendant harm from resultant behavior changes, such as reduced docosahexaenoic acid exposure from lower seafood intake, reduced uptake of childhood vaccinations and suboptimal dental care.

Mercury exposure and public health.

Mercury is a metal that is a liquid at room temperature. Mercury has a long and interesting history deriving from its use in medicine and industry, with the resultant toxicity produced. In high enough doses, all forms of mercury can produce toxicity. The most devastating tragedies related to mercury toxicity in recent history include Minamata Bay and Niagata, Japan in the 1950s, and Iraq in the 1970s. More recent mercury toxicity issues include the extreme toxicity of the dimethylmercury compound noted in 1998, the possible toxicity related to dental amalgams, and the disproved relationship between vaccines and autism related to the presence of the mercury-containing preservative, thimerosal.

[Dental amalgam and multiple sclerosis: what is the connection?]. / Amalgames dentaires et sclérose en plaques: quelle relation?

BACKGROUND: There is some debate concerning a possible relationship between dental fillings and multiple sclerosis. Many patients ask their dentist to remove fillings. TOXICITY: Dental fillings contain mercury (more than 50%) which can cross the blood-brain barrier. Massive mercurial intoxication is neurotoxic both for the central and peripheral nervous system. Dental fillings release as much mercury in 24 hours as is ingested in a normal meal, i.e. a level well under the neurotoxicity level. RELATIONSHIP: Mercurial poisoning is histologically, clinically, immunologically, and toxicollogically different from multiple sclerosis. Based on data available today, it is not warranted to propose removing dental fillings.

The science and politics of dental amalgam.

Dental amalgam--a mixture of elemental mercury and a silver-dominated metal alloy--has been the most widely used dental filling material for well over a century. Alternative materials exist but are not well suited for some important applications, and all are more expensive than amalgam. The toxic effects of occupational mercury exposure have long been known, but it was not until about 1980 that serious consideration was given to the possibility that mercury vapor escaping from amalgam fillings might be affecting health, specifically producing subtle effects on the central nervous system. Such effects have been reported among dentists and other dental personnel, whose exposures are well below industrial levels but above those from fillings alone. No large studies have been completed that examine the effects of mercury exposure from dental amalgam fillings. In the face of inadequate evidence on the possible risks of dental amalgam, countries have reacted desperately. Sweden is phasing out amalgam entirely, possibly by the end of 1997. Germany has produced guidelines for limiting its use, other countries have signaled their intention to reduce it, and others--the United States and Canada--have studied the matter but taken no action. Policy differences within Europe have made dental amalgam a test case for the European Community's new medical device regulations. Relatively little epidemiologic research has been initiated to try to answer the question of dental amalgam's possible health effects. An international effort to define and carry out a research agenda to guide public policy is called for.

Dental amalgam. III: Toxicity.

Amalgam fillings contribute to the total exposure of the population to mercury in an analytically measurable way. As a matter of principle, it is therefore desirable to minimize the exposure to mercury. At the same time, this has to be balanced against necessities of dental surgery. Considering the inevitability of using amalgam in dental surgery, there is, at present, no reason to renounce this material from a toxicological point of view. There is no indication for mobilization tests and zinc therapy in combination with the mercury exposure from amalgam fillings.