Health complaints before and at one and five years after removal of dental amalgam restorations - data from a prospective cohort study in Norway

OBJECTIVE

Health complaints attributed to dental amalgam fillings comprise both intraoral and general health complaints. There are data suggesting that patients with medically unexplained physical symptoms (MUPS) attributed to amalgam fillings show improvement in symptoms after removal of all amalgam fillings. However, data indicating changes of specific health complaints are limited. This study evaluated the changes of health complaints after removal of amalgam restorations in patients with health complaints attributed to dental amalgam fillings.

METHOD

Patients with MUPS attributed to dental amalgam (Amalgam cohort) had all their amalgam fillings removed. The participants indicated an intensity of 11 local and 12 general health complaints on numeric rating scales before the treatment and at follow-up after 1 and 5 years. The comparison groups comprising a group of healthy individuals and a group of patients with MUPS without symptom attribution to dental amalgam did not have their amalgam restorations removed.

RESULTS

In the Amalgam cohort, mean symptom intensity was lower for all 23 health complaints at follow-up at 1 year compared to baseline. Statistically significant changes were observed for specific health complaints with effect sizes between 0.36 and 0.68. At the 5-year follow-up, the intensity of symptoms remained consistently lower compared to before the amalgam removal. In the comparison groups, no significant changes of intensity of symptoms of health complaints were observed.

CONCLUSION

After removal of all amalgam restorations, both local and general health complaints were reduced. Since blinding of the treatment was not possible, specific and non-specific treatment effects cannot be separated.

Adverse reactions to dental biomaterials: Experiences from a specialty clinic

OBJECTIVES

The Dental Biomaterials Adverse Reaction Unit was initiated by the Norwegian health authorities in 1992 as a response to the public concern regarding the safety of dental amalgam and other dental materials. In this paper, experiences from the Unit are briefly summarized.

METHODS

The Norwegian health authorities' strategy included four main topics: (i) development of a manufacturer-independent system for monitoring adverse reactions related to dental materials, (ii) funding of a specialty unit for clinical examinations of referred patients, (iii) development of official guidelines for examination and treatment of patients with health complaints attributed to dental materials, and (iv) funding of an experimental treatment project for patients with health complaints attributed to dental amalgam.

RESULTS

From the start, more than 2700 adverse reaction reports were received. In the initial years, amalgam was the most frequent material mentioned in the reports. Reports about polymer-based composite materials have not increased after the prohibition of amalgam in Norway. Clinical examination of referred patients is complex and time consuming, and it is important to consider differential diagnoses. There are methodological challenges associated with the design of experimental treatments used on patients with adverse reactions attributed to dental materials. However, the results from the treatment project indicate lower symptom load after replacement of amalgam with other dental restorative materials.

SIGNIFICANCE

Producer independent adverse reaction reporting can provide valuable information about the safety of these materials and could serve as a complement to the mandatory reporting system described in the European medical device regulations (MDR).

Dental material allergies and oral soft tissue reactions

Dental materials can cause reactions to the oral mucosa and present to the general dental practitioner. These are often referred to as 'allergies' but are frequently lichenoid reactions. Most of these are related to dental amalgam restorations and can be remedied by replacing the restoration with another suitable material. Other metals, including gold, palladium, nickel and chrome, have also been reported to trigger mucosal changes. Less commonly, issues arise from other restorative materials, including denture acrylics, composites and glass polyalkenoates. Reactions are also reported due to endodontic and sealing materials. It is unclear what role skin 'patch' testing has in managing dental material allergies. This article aims to give the practitioner a clearer picture of dental material allergy issues and how they should be approached in primary dental practice.

Is amalgam removal in patients with medically unexplained physical symptoms cost-effective? A prospective cohort and decision modelling study in Norway

There are many patients in general practice with health complaints that cannot be medically explained. Some of these patients attribute their health complaints to dental amalgam restorations. This study examined the cost-effectiveness of the removal of amalgam restorations in patients with medically unexplained physical symptoms (MUPS) attributed to amalgam fillings compared to usual care, based on a prospective cohort study in Norway. Costs were determined using a micro-costing approach at the individual level. Health outcomes were documented at baseline and approximately two years later for both the intervention and the usual care using EQ-5D-5L. Quality adjusted life year (QALY) was used as a main outcome measure. A decision analytical model was developed to estimate the incremental cost-effectiveness of the intervention. Both probabilistic and one-way sensitivity analyses were conducted to assess the impact of uncertainty in costs and effectiveness. In patients who attribute health complaints to dental amalgam restorations and fulfil the inclusion and exclusion criteria, amalgam removal is associated with modest increase in costs at societal level as well as improved health outcomes. In the base-case analysis, the mean incremental cost per patient in the amalgam group was NOK 19 416 compared to the MUPS group, while mean incremental QALY was 0.119 with a time horizon of two years. Thus, the incremental costs per QALY of the intervention was NOK 162 680, which is usually considered cost effective in Norway. The estimated incremental cost per QALY decreased with increasing time horizon, and amalgam removal was found to be cost saving over both 5 and 10 years. This study provides insight into the costs and health outcomes associated with the removal of amalgam restorations in patients who attribute health complaints to dental amalgam fillings, which are appropriate instruments to inform health care priorities.

Validity and responsiveness of GHC-index in patients with amalgam-attributed health complaints

OBJECTIVE

Many patients have medically unexplained physical symptoms (MUPS); some of them attribute their health complaints to dental amalgam fillings. The aim of this study was to assess the validity and responsiveness of General Health Complaints index (GHC-index) for measuring the symptom load in MUPS patients compared to the widely used symptom outcome measure, Giessen Subjective Complaints List (GBB-24).

METHODS

Three outcome measures - GHC-index, GBB-24, and Munich Amalgam Scale (MAS) - were administered at baseline and 12 months after removal of all dental amalgam restorations. The validity and responsiveness of these symptom measures were tested against external anchors: bodily distress syndrome (BDS), SF-36 vitality, and visual analogue scale (VAS). We tested both convergent and known group validities. We also examined the predictive validity and responsiveness to changes for each instrument.

RESULTS

All the main outcome measures showed evidence of convergent and known group validities. The GHC-index, GBB-24 and MAS were all able to detect the anticipated differences in BDS and Energy. But the GBB-24 was more efficient in discriminating the BDS compared with the GHC-index (relative efficiency: RE = 0.69; 95% CI: 0.41-0.96) and MAS (RE = 0.59; 95% CI: 0.32-0.86). Each main outcome variable revealed good predictive validity for vitality (standardized coefficient: b ≈ 0.71 and R² ≈ 0.50). Moderate to high sensitivity to change over time was demonstrated, with GHC-index performing better.

CONCLUSION

The GHC-index is a valid and responsive instrument for assessing symptom load in MUPS patients attributing their health complaints to amalgam fillings and undergoing amalgam removal.

Validity and responsiveness of EQ-5D-5L and SF-6D in patients with health complaints attributed to their amalgam fillings: a prospective cohort study of patients undergoing amalgam removal

Background

Evidence of health utility changes in patients who suffer from longstanding health complaints attributed to dental amalgam fillings are limited. The change in health utility outcomes enables calculating quality-adjusted life-year (QALY) and facilitates the comparison with other health conditions. The purpose of this study was to estimate the validity and responsiveness of the EQ-5D-5L and SF-6D utilities following removal of dental amalgam fillings in patients with health complaints attributed to their amalgam fillings, and examine the ability of these instruments to detect minimally important changes over time.

Methods

Patients with medically unexplained physical symptoms, which they attributed to dental amalgam restorations, were recruited to a prospective cohort study in Norway. Two health state utility instruments, EQ-5D-5L and SF-6D, as well as self-reported general health complaints (GHC-index) and visual analogue scale (EQ-VAS) were administered to all patients (n = 32) at baseline and at follow-up. The last two were used as criteria measures. Concurrent and predictive validities were examined using correlation coefficients. Responsiveness was assessed by the effect size (ES), standardized response mean (SRM), and relative efficiency. Minimally important change (MIC) was examined by distribution and anchor-based approaches.

Results

Concurrent validity of the EQ-5D-5L was similar to that of SF-6D utility. EQ-5D-5L was more responsive than SF-6D: the ES were 0.73 and 0.58 for EQ-5D-5L and SF-6D, respectively; SRM were 0.76 and 0.67, respectively. EQ-5D-5L was more efficient than SF-6D in detecting changes, but both were less efficient compared to criteria-based measures. The estimated MIC of EQ-5D-5L value set was 0.108 and 0.118 based on distribution and anchor-based approaches, respectively. The corresponding values for SF-6D were 0.048 and 0.064, respectively.

Conclusions

In patients with health complaints attributed to dental amalgam undergoing amalgam removal, both EQ-5D-5L and SF-6D showed reasonable concurrent and predictive validity and acceptable responsiveness. The EQ-5D-5L utility appears to be more responsive compared to SF-6D.

Trial registration The research was registered at ClinicalTrials.gov., NCT01682278. Registered 10 September 2012, https://clinicaltrials.gov/ct2/show/NCT01682278.

Removal of dental amalgam restorations in patients with health complaints attributed to amalgam: A prospective cohort study

BACKGROUND

The Norwegian Ministry of Health and Care Services initiated a project including experimental treatment for patients with health complaints attributed to amalgam restorations.

OBJECTIVE

The aim was to evaluate changes of general health complaints in patients who participated in the project and had all amalgam restorations removed.

METHODS

The project was designed as a prospective cohort study and organised by the Dental Biomaterials Adverse Reaction Unit in Bergen, Norway. The dental treatment was provided by the patient's local dentist. The main target group consisted of patients with medically unexplained physical symptoms, attributed to dental amalgam restorations (Amalgam cohort). The primary comparison group consisted of patients with medically unexplained physical symptoms without attribution to dental amalgam restorations (MUPS cohort). Primary outcome was self-reported general health complaints (GHC index) at follow-up 12-months after completed amalgam removal.

RESULTS

In the Amalgam cohort, a significant reduction of GHC index from 43.3 (SD 17.8) at baseline to 30.5 (SD 14.4) at follow-up (mean reduction 12.8, SD 15.9; n = 32; P < .001) was observed. The change scores for GHC index indicated that the reduction of complaints was significantly higher (P = .004) in the Amalgam cohort compared with the MUPS cohort (mean reduction 1.2, SD 12.3, n = 28). After adjustment for age, gender, education and baseline GHC index, the mean adjusted difference was -8.0 (95% confidence interval from -15.4 to -0.5; P = .036).

CONCLUSION

In a group of patients with medically unexplained physical symptoms, which they attributed to dental amalgam restorations, removal of amalgam restorations was followed by a significant reduction of health complaints.

The use of silver amalgam for treatment of shell ulcerations in turtles: 60 cases

Shell ulcers were diagnosed based on clinical appearance in 60 turtles. Under general anaesthesia, surgical curettage was performed using a burr mounted on a micro-grinder. A calcium hydroxide paste was applied to the debrided lesions before the application of restorative material. Lesions were completely filled with rapidly hardening silver amalgam. Treated terrapins were hospitalised in dry containers and later were housed in tanks with controlled temperature 24 hours. Fillings were found spontaneously expulsed at various periods after placement. No signs of mercury poisoning or tissue reaction to the prosthesis were apparent.

Long term changes in health complaints after removal of amalgam restorations

OBJECTIVE

Concerns over adverse effects of mercury released from dental amalgam sometimes lead patients to request removal of their amalgam restorations. Several studies report improvement of subjective health after removal of amalgam restorations, but the mechanisms are unclear. The aim of this paper is to present data on long term changes in intensity of health complaints after amalgam removal in a group of patients with health complaints self-attributed to dental amalgam. Data from the five years follow-up in a clinical trial are presented and related to potential determinants of change.

MATERIALS AND METHODS

Patients previously referred to a specialty unit for health complaints attributed to amalgam restorations were included in the study. The 20 participants who were allocated to the treatment group had all amalgam restorations removed and replaced with other dental restorative materials. Intensity of health complaints was calculated from questionnaire data and personality variables were measured by MMPI-2.

RESULTS

At the follow-up five years after the amalgam removal was completed, intensity of general health complaints was significantly reduced (p=.001), but the symptom load was still high. The reduction was significantly correlated with concentration of mercury in urine at pre-treatment. There were no significant correlations with personality variables.

CONCLUSIONS

Removal of amalgam restorations was followed by a long term reduction of general health complaints, which was associated with mercury concentration in urine before amalgam removal. Additional studies are needed to confirm the potential mechanisms for the observed reduction.

Health Complaints Attributed to Dental Amalgam: A Retrospective Survey Exploring Perceived Health Changes Related to Amalgam Removal

BACKGROUND

Many patients have complex health complaints they attribute to dental amalgam. There is some evidence of symptom relief after removal of amalgam.

OBJECTIVE

The aims of this study were to assess the total symptom load in patients with all their amalgam fillings removed, and to investigate the self-reported improvement of health with regard to precautions taken under amalgam removal and time since removal.

METHODS

The survey was distributed to all members (n=999) of the Norwegian Dental patients association in 2011. The study participants returned the questionnaires anonymously by means of a pre-stamped envelope. The questionnaire asked for sociodemographic data, subjectively perceived health status, complaints persisting after amalgam removal and self-reported changes in symptoms after amalgam removal.

RESULTS

A total of 324 participants were included in the study. The majority of the participants reported improved health after amalgam removal, even though the mean degree of severity of complaints was still high. Exhaustion and musculoskeletal complaints were most severe, and reflects the fact that 38% of the participants reported poor to very poor current health. With regard to amalgam removal, associations between improved health, number of precautions applied, and time since removal were found.

CONCLUSION

Most of the participants in this study reported improvement of health after amalgam removal even though they still suffered a high complaint load. Since absolute symptom load is a robust predictor for general health outcome and socioeconomic burden for society, a possible intervention, which enables patients to further improve their health status is desirable.

"Struggle to obtain redress": Women's experiences of living with symptoms attributed to dental restorative materials and/or electromagnetic fields

The aim of this study was to explore the experiences of illness and the encounters with health care professionals among women who attributed their symptoms and illness to either dental restorative materials and/or electromagnetic fields, despite the fact that research on health effects from dental fillings or electricity has failed to substantiate the reported symptoms. Thirteen women (aged 37-63 years) were invited to the study and a qualitative approach was chosen as the study design, and data were collected using semi-structured interviews. The analysis was conducted with a constant comparative method, according to Grounded Theory. The analysis of the results can be described with the core category, "Struggle to obtain redress," the two categories, "Stricken with illness" and "A blot in the protocol," and five subcategories. The core category represents the women's fight for approval and arose in the conflict between their experience of developing a severe illness and the doctors' or dentists' rejection of the symptoms as a disease, which made the women feel like malingerers. The informants experienced better support and confirmation from alternative medicine practitioners. However, sick-leave certificates from alternative medicine practitioners were not approved and this led to a continuous cycle of visits in the health care system. To avoid conflicting encounters, it is important for caregivers to listen to the patient's explanatory models and experience of illness, even if a medical answer cannot be given.

Media influence on risk competence in self-medication and self-treatment

Media play an important role in the reception of health risks; thus, media competence is important for enhancing the risk competence of patients and consumers. In addition to life-long health education, risk competence particularly requires careful handling of health information because, at present, the key problem is not the lack of sufficient information on health topics but the quality of such information. Patients and consumers of health procedures and health products also require information which relates to their daily life and matches their life style.

Patients' experiences of changes in health complaints before, during, and after removal of dental amalgam

In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients’ assigning meaning to illness experiences.

Longitudinal analysis of the association between removal of dental amalgam, urine mercury and 14 self-reported health symptoms

BACKGROUND

Mercury vapor poses a known health risk with no clearly established safe level of exposure. Consequently there is debate over whether the level of prolonged exposure to mercury vapor from dental amalgam fillings, combining approximately 50% mercury with other metals, is sufficiently high to represent a risk to health. The objective of our study is to determine if mercury exposure from amalgam fillings is associated with risk of adverse health effects.

METHODS

In a large longitudinal non-blind sample of participants from a preventative health program in Calgary, Canada we compared number of amalgam fillings, urine mercury measures and changes in 14 self-reported health symptoms, proposed to be mercury dependent sub-clinical measures of mental and physical health. The likelihood of change over one year in a sample of persons who had their fillings removed was compared to a sample of persons who had not had their fillings removed. We use non-parametric statistical tests to determine if differences in urine mercury were statistically significant between sample groups. Logistic regression models were used to estimate the likelihood of observing symptom improvement or worsening in the sample groups.

RESULTS

At baseline, individuals with dental amalgam fillings have double the measured urine mercury compared to a control group of persons who have never had amalgam fillings. Removal of amalgam fillings decreases measured urine mercury to levels in persons without amalgam fillings. Although urine mercury levels in our sample are considered by Health Canada to be too low to pose health risks, removal of amalgam fillings reduced the likelihood of self-reported symptom deterioration and increased the likelihood of symptom improvement in comparison to people who retained their amalgam fillings.

CONCLUSIONS

Our findings suggest that mercury exposure from amalgam fillings adversely impact health and therefore are a health risk. The use of safer alternative materials for dental fillings should be encouraged to avoid the increased risk of health deterioration associated with unnecessary exposure to mercury.

Characterization of health complaints before and after removal of amalgam fillings--3-year follow-up

OBJECTIVE

Some patients attribute health complaints to amalgam fillings and report improvement of health after replacement of amalgam fillings. The aim of the present study was to characterize the changes of different health complaints after replacement of amalgam fillings and compare with an external reference group from the general population.

MATERIALS AND METHODS

The study group included 20 patients with health complaints attributed to amalgam fillings who were participants in the treatment group of a clinical trial at the Norwegian Dental Biomaterials Adverse Reaction Unit. The patients were asked to indicate the intensity of local and general health complaints on numeric rating scales (0-10) before removal of amalgam fillings and at follow-up 3 years after removal. Data from the patient group were compared with data from an external reference group (n = 441).

RESULTS

Before treatment the mean intensity of complaints were on a higher level in the treatment group compared to the reference group. The most frequently reported complaints in the treatment group were gastrointestinal symptoms, fatigue, pain from muscles and joints, symptoms from ear/nose/throat and difficulty concentrating. From pre-treatment examination to the 3-year follow-up 20 of 23 health complaints decreased, being statistically significant for taste disturbances, pain from muscles and joints, gastrointestinal complaints, complaints from ear/nose/throat and fatigue.

CONCLUSIONS

The inter-individual variation of intensities of health complaints was considerable and the reduction of health complaints varied for the different complaints. Several factors may be of importance for the observed reduction of complaint intensity.

Does a specific dental amalgam syndrome exist? A comparative study

OBJECTIVE

The aim of this article was to investigate whether there is evidence for a specific syndrome of health problems attributed to dental amalgam.

MATERIAL AND METHODS

A secondary and retrospective analysis of two different databases was performed: (a) 90 patients (47% female, mean (SD) age 34 (6) years) of a clinical trial to remove amalgam fillings who attribute their health complaints to dental amalgam, and (b) 116 patients (62% female, mean (SD) age 37 (8) years) from an outpatient unit for environmental medicine who attribute their symptoms to environmental sources other than amalgam.

RESULTS

The samples differed in age, sex, and educational level. No statistically significant differences between either of the groups were found in overall psychological distress, intensity of the symptoms, or in numbers of self-reported symptoms in the Symptom Check List after controlling for age, sex, and education (Mean Global Severity Index 0.62 versus 0.63). Patients from the amalgam group showed mean values for private and public self-consciousness similar to the population norm, while patients from the comparison group had statistically significantly decreased mean values. While the amalgam group more frequently reported mental symptoms, patients from the comparison group had a higher prevalence of somatic symptoms.

CONCLUSIONS

The results showed some differences in symptomatology, while general psychological distress was similar in both groups, indicating no strong evidence for an amalgam-specific syndrome.

Reliance on social security benefits by Swedish patients with ill-health attributed to dental fillings: a register-based cohort study

Background

Some people attribute their ill health to dental filling materials, experiencing a variety of symptoms. Yet, it is not known if they continue to financially support themselves by work or become reliant on different types of social security benefits. The aim of this study was to analyse reliance on different forms of social security benefits by patients who attribute their poor health to dental filling materials.

Methods

A longitudinal cohort study with a 13-year follow up. The subjects included were 505 patients attributing their ill health to dental restorative materials, who applied for subsidised filling replacement. They were compared to a cohort of matched controls representing the general population (three controls per patient). Annual individual data on disability pension, sick leave, unemployment benefits, and socio-demographic factors was obtained from Statistics Sweden. Generalized estimating equations were used to test for differences between cohorts in number of days on different types of social security benefits.

Results

The cohort of dental filling patients had a significantly higher number of days on sick leave and disability pension than the general population. The test of an overall interaction effect between time and cohort showed a significant difference between the two cohorts regarding both sick leave and disability pension. In the replacement cohort, the highest number of sick-leave days was recorded in the year they applied for subsidised replacement of fillings. While sick leave decreased following the year of application, the number of days on disability pension increased and peaked at the end of follow-up.

Conclusions

Ill health related to dental materials is likely to be associated with dependence on social security benefits. Dental filling replacement does not seem to improve workforce participation.

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.

Changes in health complaints after removal of amalgam fillings

The aim of the present study was to investigate whether removal of all amalgam fillings was associated with long-term changes in health complaints in a group of patients who attributed subjective health complaints to amalgam fillings. Patients previously examined at the Norwegian Dental Biomaterials Adverse Reaction Unit were included in the study and assigned to a treatment group (n = 20) and a reference group (n = 20). Participants in the treatment group had all amalgam fillings replaced with other restorative materials. Follow-ups took place 3 months, 1 and 3 years after removal of all amalgam fillings. There was no intervention in the reference group. Subjective health complaints were measured by numeric rating scales in both groups. Analysis of covariance was used to compare changes in health complaints over time in the two groups. In the treatment group, there were significant reductions in intra-oral and general health complaints from inclusion into study to the 3-year follow-up. In the reference group, changes in the same period were not significant. Comparisons between the groups showed that reductions in intra-oral and general health complaints in the treatment group were significantly different from the changes in the reference group. The mechanisms behind this remain to be identified. Reduced exposure to dental amalgam, patient-centred treatment and follow-ups, and elimination of worry are factors that may have influenced the results.

Removal of dental amalgam fillings and its influence on saliva morphological picture - case report

The influence of dental restorative materials on patients' general and oral health is the main interest of many researchers but the question of their safety is still under consideration. An otherwise healthy 23-year-old patient with no history of oral abnormalities was examined. Dental amalgam restorations were replaced by composite resin material. Salivary smears prepared two days and two weeks after the amalgam removal were compared with those taken before the procedure.

Effects of selenite and chelating agents on mammalian thioredoxin reductase inhibited by mercury: implications for treatment of mercury poisoning

Mercury toxicity is a highly interesting topic in biomedicine due to the severe endpoints and treatment limitations. Selenite serves as an antagonist of mercury toxicity, but the molecular mechanism of detoxification is not clear. Inhibition of the selenoenzyme thioredoxin reductase (TrxR) is a suggested mechanism of toxicity. Here, we demonstrated enhanced inhibition of activity by inorganic and organic mercury compounds in NADPH-reduced TrxR, consistent with binding of mercury also to the active site selenolthiol. On treatment with 5 μM selenite and NADPH, TrxR inactivated by HgCl(2) displayed almost full recovery of activity. Structural analysis indicated that mercury was complexed with TrxR, but enzyme-generated selenide removed mercury as mercury selenide, regenerating the active site selenocysteine and cysteine residues required for activity. The antagonistic effects on TrxR inhibition were extended to endogenous antioxidants, such as GSH, and clinically used exogenous chelating agents BAL, DMPS, DMSA, and α-lipoic acid. Consistent with the in vitro results, recovery of TrxR activity and cell viability by selenite was observed in HgCl(2)-treated HEK 293 cells. These results stress the role of TrxR as a target of mercurials and provide the mechanism of selenite as a detoxification agent for mercury poisoning.

Stressful negative life events and amalgam-related complaints

OBJECTIVES

The role of stressful life events in the onset of self-reported amalgam-related complaints is unclear. The aim of this study was to examine the relationship between life events and amalgam-related complaints.

METHOD

The participants were selected from a longitudinal population-based study. One-to-one matching of 337 participants with amalgam-related complaints to 337 participants without such complaints was performed. For 81 of the participants with amalgam-related complaints and their matched controls, data was also available approximately 5 years before the onset of complaints, making longitudinal analysis possible. All participants completed questionnaires assessing the occurrence of 55 life events.

RESULTS

The results showed that many participants with amalgam-related complaints experienced negative life events before and at the onset of amalgam-related complaints. They also reported more unexpected and uncontrollable events difficult to adjust to in comparison with controls. The groups did not differ on positive or neutral life events. Somatic illness or surgical operation was the most common life event. Death of a very close family member and a major change in financial situation were also commonly reported.

CONCLUSIONS

This study indicates that adverse negative life events could play a vital role in understanding and explaining amalgam-related complaints.

Predictors of treatment outcomes after removal of amalgam fillings: associations between subjective symptoms, psychometric variables and mercury levels

OBJECTIVE

This analysis aimed to study predictors of different treatment outcomes and associations between subjective symptoms, psychometric variables and mercury levels in patients who subjectively attributed their health problems to dental amalgam.

MATERIAL AND METHODS

A secondary and retrospective analysis of data of a recently published randomized clinical trial was performed. Seventy-eight patients [44% female, mean (SD) age 35 (6) years, randomly assigned to either amalgam removal or a health promotion program] were included into statistical analysis. Prior to intervention and 12 months later, questionnaires for assessing symptoms, psychological distress and health status were presented, and mercury levels in blood and urine were determined.

RESULTS

The patients' personality profile at study onset was characterized by slightly reduced extraversion and slightly elevated emotional instability. Overall, subjective symptoms decreased slightly and there were no statistically significant differences in the decrease of symptoms after intervention between both groups. Decrease of mercury levels after intervention was closely associated with removal of amalgam fillings (r(mult) = 0.64 in regression analysis). Statistically significant correlations could be found between mercury levels and subjective symptoms with respect to baseline (r = 0.29-0.39) and to changes after intervention (r = 0.24-0.42), but not for psychological distress (r = 0.05-0.25) and health related quality of life (r = -0.03-0.18). Prediction of symptom improvement after intervention was poor (r(mult) = 0.44).

CONCLUSIONS

Results contribute some new aspects to the inconsistent findings in the literature with respect to associations between symptoms and subtoxic mercury levels. More emphasis should be placed on exploring individual vulnerability for amalgam sensitivity.

JEM spotlight: metal speciation related to neurotoxicity in humans

Improved living conditions have led to a steady increase in the life expectancy of humans in most countries. However, this is accompanied by an increased probability of suffering from neurodegenerative diseases like Alzheimer's disease or Parkinson's disease. Unfortunately, the therapeutic possibilities for curing these diseases are very limited up to now. Many studies indicate that a variety of environmental factors contribute to the initiation and promotion of neurodegenerative diseases. For example, the role of metal exposure and disturbance of metal homeostasis in the brain is discussed in this respect. However, most studies focus on the neurological and toxicological aspects but not on a detailed characterisation of the species of the involved metals. Therefore, this review summarizes the neurotoxic effects of selected metals on humans and focuses on contributions from trace element speciation analysis with relevance to neuroscientific research. In spite of the advance in instrumentation and methodology of speciation analysis there are few applications for matrices like cerebrospinal fluid which is due to limited access to these samples and analytical challenges caused by matrix interferences, low concentrations and limited stability of many trace element species of interest. The most relevant neurotoxic metals aluminium, lead, manganese and mercury are reviewed in detail while further metals like cadmium, arsenic, bismuth and tin are briefly discussed. Current results indicate that knowledge on trace element speciation can contribute to a better understanding of the transport of metals across the neural barriers and potentially of their role in diseased human brains.