Effect of placement of amalgam restorations on urinary mercury concentration

Association between dental amalgam restoration and urine mercury concentrations among young women: a cross-sectional study

BACKGROUND

The association between dental amalgam fillings and urine mercury concentrations was investigated in this study to assess the health risks associated with dental amalgams.

METHODS

This cross-sectional study included 99 women in their 20s who visited the dental clinic in Daegu, Korea. The 99 participants were composed of 68 subjects who had dental amalgam fillings (exposure group) and 31 subjects who did not have dental amalgam fillings (nonexposure group). Oral examinations were conducted by a single dental hygienist, sociodemographic features were investigated as confounding variables, and urine mercury concentrations were measured using an automatic mercury analyzer.

RESULTS

The mean±standard deviation of the urine mercury concentrations of the exposure and nonexposure groups were 1.50±1.78 μg/g creatinine and 0.53±0.63 μg/g creatinine, respectively. The exposure group showed significantly higher levels than the nonexposure group (p<0.01). The urine mercury concentration significantly increased with an increase in the number of teeth filled with amalgam, cavity surfaces involved, and number of defective amalgam fillings, and according to the latest exposure time (p<0.001). In the multiple regression analysis of amalgam-related factors and urine mercury concentrations after correction for confounding factors, the urine mercury concentration in the group with six or more amalgam-filled teeth, 11 or more cavity surfaces, and two or more defective amalgams was significantly higher than that in the nonexposure group (p<0.001).

CONCLUSION

According to this study, exposure to dental amalgams was confirmed to significantly affect urine mercury concentrations.

Biocompatibility of dental amalgams

Objective. The purpose of this review paper is to review the literature regarding the toxicology of mercury from dental amalgam and evaluate current statements on dental amalgam. Materials and Methods. Two key-words “dental amalgam” and “toxicity” were used to search publications on dental amalgam biocompatibility published in peer-reviewed journals written in English. Manual search was also conducted. The most recent declarations and statements were evaluated using information available on the internet. Case reports were excluded from the study. Results. The literature show that mercury released from dental amalgam restorations does not contribute to systemic disease or systemic toxicological effects. No significant effects on the immune system have been demonstrated with the amounts of mercury released from dental amalgam restorations. Only very rarely have there been reported allergic reactions to mercury from amalgam restorations. No evidence supports a relationship between mercury released from dental amalgam and neurological diseases. Almost all of the declarations accessed by the internet stated by official organizations concluded that current data are not sufficient to relate various complaints and mercury release from dental amalgam. Conclusions. Available scientific data do not justify the discontinuation of amalgam use from dental practice or replacement with alternative restorative dental materials.

Dental amalgam exposure and urinary mercury levels in children: the New England Children's Amalgam Trial

BACKGROUND

Urinary mercury (U-Hg) excretion is a commonly used biomarker for mercury exposure from dental amalgam restorations.

OBJECTIVES

Our goal was to determine the most efficient measure of dental amalgam exposure for use in analyses concerning U-Hg in children.

METHODS

We analyzed time-sensitive longitudinal amalgam exposure data in children randomized to amalgam restorations (n = 267) during the 5-year New England Children's Amalgam Trial. We calculated 8 measures of amalgam, evaluating current versus cumulative exposure, teeth versus surfaces, and total versus posterior occlusal amalgams. Urine samples collected during follow-up years 3-5 were analyzed for mercury excretion. Multivariate models for current and cumulative U-Hg excretion estimated associations between exposures and U-Hg.

RESULTS

At the end of follow-up, the average (+/- SD) cumulative exposure was 10.3 +/- 6.1 surfaces and 5.7 +/- 2.9 teeth ever filled with amalgam, corresponding to 30 +/- 21 surface-years. Amalgam measures and U-Hg were moderately correlated. Of amalgam exposure measures, the current total of amalgam surfaces was the most robust predictor of current U-Hg, whereas posterior occlusal surface-years was best for cumulative U-Hg. In multivariate models, each additional amalgam surface present was associated with a 9% increase in current U-Hg, and each additional posterior occlusal surface-year was associated with a 3% increase in cumulative U-Hg excretion (p < 0.001).

CONCLUSIONS

One single measure of amalgam exposure is insufficient. Studies of cumulative effects of mercury from amalgam exposure in children are likely to have improved validity and precision if time-sensitive amalgam exposure measures are used. In contrast, simple counts of current amalgam fillings are adequate to capture amalgam-related current U-Hg.

Urinary mercury excretion following amalgam filling in children

OBJECTIVES

Dental amalgam is the major source of inorganic mercury exposure in the general population. Dental amalgam contains approximately 50% mercury, which is a toxic element. Since children are more at risk for mercury toxicity, we aimed to study prospectively the effects of amalgam filling on urinary mercury excretion in 5- to 7-year-old children.

METHODS

Children admitted to the Pedodontics Department with no previous amalgam filling, and in a good state of health with one or more carious posterior teeth, were selected. All fillings were placed in one session for each child using Sina (Iran) amalgam powder and Degussa (Germany) mercury, which were mixed by an automated electric amalgamator (Dentomate 3, Germany). Urinary mercury concentrations were estimated before and 9-12 days after amalgam filling by atomic absorption using the mercuric hydride system.

RESULTS

Forty-three children (20 male, 23 female) aged 5.95+/-0.92 years and weighing 19.09+/-3.10 kg were studied. Urinary mercury concentrations before and after amalgam filling were 3.83+/-2.45 and 5.14+/-3.14 microg/L, respectively (p = 0.001). There were no statistically significant correlations between the urinary mercury concentrations and any other variables, including the number and surfaces of filled teeth, weight, age, and sex.

CONCLUSION

Although there were highly significant increases in urinary mercury concentrations after amalgam filling, no significant correlation was found between the urinary mercury concentration and the amounts of filled amalgam. Additional investigation is required concerning the effects of mercury release from amalgam.

Mercury in dental amalgam--a public health concern?

Dental amalgam has been the subject of intermittent controversy since it was introduced into dental practice approximately 150 years ago. The controversy has centered on the use of mercury in dental amalgam and the potential health implications to dental patients and dental health professionals from mercury exposure. In recent years the debate over the use of dental amalgam has intensified due to several articles in professional journals and media coverage by television and the press. This paper reviews the recent literature regarding dental amalgam, describes the activities of the antiamalgamists, examines the alternatives to dental amalgam, and reviews the recommendations for additional research. The existing scientific evidence does not demonstrate that mercury in dental amalgam poses a public health hazard. However, researchers on both sides of the controversy agree that much remains to be examined about the health implications of dental amalgam and that the subject merits continued research.

Factors affecting blood mercury concentrations in practicing dentists

It has been suggested that mercury vapor may be transformed into highly toxic organomercury compounds by micro-organisms in the oral cavity and gastrointestinal tract. If this hypothesis is correct, practicing dentists might be expected to have concentrations of organic mercury in their blood higher than that found in non-dentists. Blood mercury concentrations of practicing dentists and non-dentists were determined by means of cold-vapor atomic absorption spectrophotometry. Potential sources of mercury exposure were identified in both dentists and non-dentists through a questionnaire completed at the time of sampling. Concentrations of total and inorganic blood mercury were significantly higher in dentists than in non-dentists. The organomercury concentrations of the two groups were not statistically different (p greater than or equal to 0.05). The high concentration of inorganic mercury in the blood of dentists was not related to the organomercury level, suggesting that biotransformation of inorganic mercury to organomercury does not occur in vivo. However, the concentration of blood organomercury was positively correlated with the frequency of fish consumption. There was no correlation between the number of amalgam restorations and the concentration of inorganic blood mercury for both groups. Accidental mercury spills in the dental operatory may contribute most to the concentration of inorganic blood mercury in the blood of dentists.

Dental amalgam. Designs for research in human populations

Questions have been raised about the safety of dental amalgam. The main point of contention is whether the mercury contained in dental restorations is released in sufficient quantities to pose a public health hazard. Most scientists agree that current evidence is not sufficient to show that amalgam restorations pose a general health threat. But researchers on both sides of this debate agree that much remains to be learned about any potential toxicity of dental amalgam--an issue serious enough to merit additional research.