adam

Background: Previous studies have reported an increase in the mercury release from dental amalgam restorations, following exposure to electromagnetic fields generated by sources such as mobile phones and magnetic resonance imaging (MRI). It has also been shown that MRI increases microleakage of amalgam restorations. In this study, Helmholtz coils are used for generating pulsed electromagnetic fields (PEMF).

Objectives: The purpose of this study was to evaluate the effect of PEMFs on microleakage of amalgam restorations, using a pair of Helmholtz coils.
Patients and Methods: Standardized class V cavities were prepared on the facial surfaces of 46 non-carious extracted human premolars. Then, the samples were randomly divided into experimental and control groups, each containing 23 teeth. The experimental group was exposed to the uniform magnetic fields generated by a pair helmholtz coils. The magnetic field strength at the central point of the two coils was 0.1 mT. All specimens were placed in 2% basic fuchsin solution. Then the teeth were sectioned, examined under a stereomicroscope, and scored for microleakage according to the degree of dye penetration.

Results: There was no significant difference between the two groups regarding the microleakage score.
Conclusions: The results of the present study suggest that PEMF exposure does not have adverse effects on microleakage of amalgam restorations.

“BACKGROUND:
Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP.

METHODS:
Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups) and the remaining 15 samples were placed in buffered phosphate solution (as control groups) with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Analyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan). Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05).

RESULTS:
The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P < 0.001). In addition, the amount of mercury released from dental amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P < 0.001). CONCLUSION: The amount of mercury release is inversely proportional to the silver content of dental amalgam."

A latency period preceding neurotoxicity is a common characteristic in the dose-response relationship induced by organic mercury. Latency periods have typically been observed with genotoxicants in carcinogenesis, with cancer being manifested a long time after the initiating event. These observations indicate that even a very small dose may cause extensive adverse effects later in life, so the toxicity of the genotoxic compound is dose and time-dependent. In children, methylmercury exposure during pregnancy (in utero) has been associated with delays in reaching developmental milestones (e.g., age at first walking) and decreases in intelligence, increasing in severity with increasing exposure. Ethylmercury exposure from thimerosal in some vaccines has been associated, in some studies, with autism and other neurological disorders in children. In this paper, we have examined whether dose-response data from in vitro and in vivo organic mercury toxicity studies fit the Druckrey-Küpfmüller equation c·t(n)=constant (c=exposure concentration, t=latency period), first established for genotoxic carcinogens, and whether or not irreversible effects are enhanced by time of exposure (n≥1), or else toxic effects are dose-dependent while time has only minor influence on the adverse outcome (n<1). The mode of action underlying time-dependent toxicity is irreversible binding to critical receptors causing adverse and cumulative effects. The results indicate that the Druckrey-Küpfmüller equation describes well the dose-response characteristics of organic mercury induced neurotoxic effects. This amounts to a paradigm shift in chemical risk assessment of mercurial compounds and highlights that it is vital to perform toxicity testing geared to investigate time-dependent effects.

Background: To determine in vivo oxidative stresses induced by dental amalgam, composite resin, and glass ionomer cement (GIC).
Materials and Methods: A total of 60 patients were selected for the study between the ages of 15 and 40 years. Informed consent and Institutional Ethical Approval was obtained. The samples were divided into three groups depending on the type of restorative material planned for them, i.e., silver amalgam, composite resin, and GIC. Saliva was collected before restoration, 24 h, 7 days, and 14 days after restoration. The salivary oxidative stress malondialdehyde (MDA) was measured and statistically analyzed using Mann–Whitney test, Kruskal–Wallis test, and Friedman’s test.

Results: The results show that the patients treated with amalgam restoration had shown significantly higher values as compared to composite and GIC at all the three-time intervals studied.

Conclusion: This study revealed that amalgam fillings were associated with the highest oxidative stress marker MDA as compared with composite and glass ionomer restoration at all the three-time intervals studied. Even after 14 days, the values were much higher indicating free ion leaching from the restoration.

“METHODS:
In this longitudinal study, 463, 367 and 348 children, 8-11 years of age, were evaluated at baseline, and at the first and second follow-up visits, respectively. The interval between each survey was 6 months. For the oral examination and urine sample, the amalgam-filled tooth surface (TS), and U-Hg and creatinine concentrations of participants were determined, and the cumulative amalgam-filled TS and cumulative creatinine-adjusted U-Hg were calculated. To assess potential covariates, socio-demographic factors, oral health behaviour and dietary factors were surveyed by questionnaire. Data were analysed by the t-test, correlation analysis and mixed-model analysis. The statistical analyses were performed using SPSS 18.0.

RESULTS:
Children with more than one amalgam-filled TS exhibited significantly higher creatinine-adjusted U-Hg concentrations than those without, in all three survey periods (P < 0.001). The results for the current and cumulative amalgam-filled TS significantly correlated with those for the current and cumulative creatinine-adjusted U-Hg concentration, respectively, in all surveys (P < 0.001). In the repeated-measures mixed model analysis, current and cumulative amalgam-filled TS was significantly related to current and cumulative creatinine-adjusted U-Hg concentration, respectively (P < 0.001). CONCLUSIONS: Amalgam-filled TS was significantly correlated with U-Hg concentrations in children. Therefore, dental amalgam exposure can affect the systemic mercury concentration in children."

The findings of Suter and Warnakulasuriya (2015) are very promising for those interested in the underlying pathogenesis of amalgam-related oral lichenoid reactions (OLRs) (1). However, we would like to underscore the importance of clinical relevance of patch test reactions in support of the causal relation between oral lichenoid reactions and dental metal allergy (2). To achieve this goal, in our view, it is necessary to extend the ‘mercury-containing dental amalgam series of patch tests’.

Background: Although it is one of the most toxic nonradioactive elements, mercury is widely  used in dental amalgam. Mercury is a toxic element which can damage various organs such  as central nervous system, renal, respiratory and hematologic systems. The adverse health impacts associated to exposure to some common sources of electromagnetic fields including  laptop computers, mobile phones, MRI and mobile phone jammers have been evaluated by our laboratory in our previous investigations. In this study, we aimed to evaluate the effect of of X ray exposure on microleakage of amalgam restoration. Materials and Methods: Standardized class V cavities were prepared on the buccal surfaces of 46 non-carious freshly extracted human premolars. The teeth were randomly divided into experimental and control groups. Experimental group were exposed to X-ray using an intraoral radiography machine at 60 kVp, 0.1 s, 7 mA with 2.5 mm Al total filtration. The absorbed dose was 245.0 ± 0.5 µGy. All specimens were placed in 2 % basic fuchsin solution for 24 hours. Then the specimens were sectioned and microleakage was assessed according to dye penetration using a stereomicroscope. Statistical analysis was performed with the Mann-Whitney U-test. Results: Microleakage was significantly higher in the X-ray exposed teeth compared to those of the non-irradiated samples. Conclusion: The results of the present study suggest that X-ray exposure increased microleakage of amalgam restorations.

Mercury (Hg) exposure, a worldwide public health concern, predominantly takes two forms–methylmercury from fish consumption and elemental Hg from dental amalgam restorations. We recruited 630 dental professionals from an American Dental Association meeting to assess Hg body burden and primary sources of exposure in a dually exposed population. Participants described occupational practices and fish consumption patterns via questionnaire. Hg levels in biomarkers of elemental Hg (urine) and methylmercury (hair and blood) were measured with a Direct Mercury Analyzer-80 and were higher than the general US population. Geometric means (95% CI) were 1.28 (1.19-1.37) μg/l in urine, 0.60 (0.54-0.67) μg/g in hair and 3.67 (3.38-3.98) μg/l in blood. In multivariable linear regression, personal amalgams predicted urine Hg levels along with total years in dentistry, amalgams handled, working hours and sex. Fish consumption patterns predicted hair and blood Hg levels, which were higher among Asians compared with Caucasians. Five species contributed the majority of the estimated Hg intake from fish–swordfish, fresh tuna, white canned tuna, whitefish and king mackerel. When studying populations with occupational exposure to Hg, it is important to assess environmental exposures to both elemental Hg and methylmercury as these constitute a large proportion of total exposure.

BACKGROUND:
Dental amalgam is composed of approximately 50% elemental mercury. Despite concerns over the toxicity of mercury, amalgam is still the most widely used restorative material. Wi-Fi is a rapidly using local area wireless computer networking technology. To the best of our knowledge, this is the first study that evaluates the effect of exposure to Wi-Fi signals on mercury release from amalgam restorations.

METHODS:
Standard class V cavities were prepared on the buccal surfaces of 20 non-carious extracted human premolars. The teeth were randomly divided into 2 groups (n = 10). The control group was stored in non-environment. The specimens in the experimental groups were exposed to a radiofrequency radiation emitted from standard Wi Fi devices at 2.4 GHz for 20 min. The distance between the Wi-Fi router and samples was 30 cm and the router was exchanging data with a laptop computer that was placed 20 m away from the router. The concentration of mercury in the artificial saliva in the groups was evaluated by using a cold-vapor atomic absorption Mercury Analyzer System. The independent t test was used to evaluate any significant differences in mercury release between the two groups.

RESULTS:
The mean (±SD) concentration of mercury in the artificial saliva of the Wi-Fi exposed teeth samples was 0.056 ± .025 mg/L, while it was only 0.026 ± .008 mg/L in the non-exposed control samples. This difference was statistically significant (P =0.009).

CONCLUSION:
Exposure of patients with amalgam restorations to radiofrequency radiation emitted from conventional Wi-Fi devices can increase mercury release from amalgam restorations.