Mercury

“Conclusion: The results for this study show that no difference existed in the rate of replacement for amalgam vs resin composite. When restorations increased from just a single occlusal surface to additional surfaces, the rate of replacement was elevated and statistically significant for both materials. A higher caries risk status was also significant in elevating replacement rates for both materials.”

Though Multiple Sclerosis (MS) sufferers are probably genetically predisposed, toxic metal poisoning (TMP) does seem an increasingly likely environmental trigger. The technique for measuring and clearing TMP was chelation therapy using ethylene-diamine-tetracetic acid (EDTA), which revealed aluminum accumulation in both cases. The first patient, initially benefiting from removing dental fillings that had leaked mercury, also showed gadolinium accumulation from scan contrast medium, and a genomic deficiency of glutathione transferase M1. Glutathione production was impaired and hence also liver detoxification functions. The personal protocol involved glutathione administration and deutrosulfazyme to enhance oxygenation and alleviate oxidative stress. As aluminum began to clear with EDTA infusion, the extracellular/intracellular water ratio was carefully monitored, and carbohydrates limited. In the second case, aluminum poisoning responded to EDTA chelation therapy with eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA), multivitamins, and glutathione administration, again followed by deutrosulfazyme, water ratio control, and dietary correction. The two personalized protocols presented here tend to confirm the hypothesis of TMP as an environmental or iatrogenic trigger for MS, especially when inadequate detoxification lies at the root. Cleansing by chelation therapy, properly understood, can be efficacious, especially bearing in mind the altered cellular water ratio.

“Thimerosal, an organomercury compound, has been widely used as a preservative. Therefore, concerns have been raised about its neurotoxicity. We recently demonstrated perturbation of early serotonergic development by prenatal exposure to thimerosal (Ida-Eto et al. (2011) [11]). Here, we investigated whether prenatal thimerosal exposure causes persistent impairment after birth. Analysis on postnatal day 50 showed significant increase in hippocampal serotonin following thimerosal administration on embryonic day 9. Furthermore, not only serotonin, striatal dopamine was significantly increased. These results indicate that embryonic exposure to thimerosal produces lasting impairment of brain monoaminergic system, and thus every effort should be made to avoid the use of thimerosal.”

“There has long been an undercurrent within the dental profession of anti-amalgam sentiment, a ‘mercury-free’ movement. To assess whether anything is or is not scientifically wrong with amalgam, one must look to the vast literature on exposure, toxicology, and risk assessment of mercury. The subject of risk assessment goes straight to the heart of the debate over whether amalgam is safe, or not, for unrestricted use in dentistry in the population at large.”

“Methylmercury-associated effects on the cardiovascular system have been documented though discrepancies exist, and most studied populations experience elevated methylmercury exposures. No paper has investigated the impact of low-level elemental (inorganic) mercury exposure on cardiovascular risk in humans. The purpose of this study was to increase understanding of the association between mercury exposure (methylmercury and elemental mercury) and blood pressure measures in a cohort of dental professionals that experience background exposures to both mercury forms. Dental professionals were recruited during the 2010 Michigan Dental Association Annual Convention. Mercury levels in hair and urine samples were analyzed as biomarkers of methylmercury and elemental mercury exposure, respectively. Blood pressure (systolic, diastolic) was measured using an automated device. Distribution of mercury in hair (mean, range: 0.45, 0.02-5.18 µg/g) and urine (0.94, 0.03-5.54 µg/L) correspond well with the US National Health and Nutrition Examination Survey. Linear regression models revealed significant associations between diastolic blood pressure (adjusted for blood pressure medication use) and hair mercury (n=262, p=0.02). Urine mercury results opposed hair mercury in many ways. Notably, elemental mercury exposure was associated with a significant systolic blood pressure decrease (n=262, p=0.04) that was driven by the male population. Associations between blood pressure and two forms of mercury were found at exposure levels relevant to the general population, and associations varied according to type of mercury exposure and gender.”

“Human exposure to methylmercury (MeHg) and elemental mercury vapor (Hg(0)(g)) are often estimated using total Hg concentrations in hair and urine, respectively. We investigated whether Hg stable isotopes could be used to better distinguish between exposure to Hg(0)(g) versus MeHg. We found that hair from North American dental professionals was characterized by high positive ?(199)Hg values (mean = 1.86‰, 1 SD = 0.12‰, n = 11). This confirms that among people who regularly consume fish, total Hg concentrations in hair reflect exposure to MeHg. In contrast, we found that urine from the same individuals was characterized by a range of ?(199)Hg values (0.29 to 1.77‰, 2 SD = 0.06‰, n = 12) that were significantly correlated to the number of dental amalgams in each individual’s mouth. We hypothesize that fish-derived MeHg is demethylated within the body, causing mass-dependent fractionation and the excretion of inorganic Hg in urine. Mercury in urine therefore represents a mixture of demethylated fish-derived MeHg and amalgam-derived inorganic Hg. We estimate that the majority (>70%) of Hg in urine from individuals with <10 dental amalgams is derived from ingestion of MeHg in fish. These data suggest that within populations that consume fish, urine total Hg concentrations may overestimate Hg exposure from personal dental amalgams.”

“Methylmercury (MeHg) toxicity may vary widely despite similar levels of exposure. This is hypothetically related to genetic differences in enzymes metabolizing MeHg. MeHg causes oxidative stress in experimental models but little is known about its effects on humans. The aims of the present study was to evaluate the effects of polymorphisms in glutathione (GSH)-related genes (GSTM1, GSTT1, GSTP1 and GCLM) on Hg concentrations in blood and hair, as well as MeHg-related effects on catalase (CAT) andglutathione-peroxidase (GPx) activity and GSH concentrations. Study subjects were from an Amazonian population in Brazil chronically exposed to MeHg from fish. Hg in blood and hair were determined by ICP-MS, CAT, GPx and GSH were determined by spectrophotometry, and multiplex PCR (GSTM1 and GSTT1) and TaqMan assays (GSTP1 and GCLM) were used for genotyping. Mean Hg concentrations in blood and hair were 48±36 μg/L and 14±10 μg/g. Persons with the GCLM-588 TT genotype had lower blood and hair Hg than did C-allele carriers (linear regression for Hg in blood β=-0.32, p=0.017; and hair β=-0.33; p=0.0090; adjusted for fish intake, age and gender). GSTM1*0 homozygous had higher blood (β=0.20; p=0.017) and hair Hg (hair β=0.20; p=0.013). Exposure to MeHg altered antioxidant status (CAT: β=-0.086; GSH: β=-0.12; GPx: β=-0.16; all p<0.010; adjusted for gender, age and smoking). Persons with GSTM1*0 had higher CAT activity in the blood than those with GSTM1. Our data thus indicate that some GSH-relatedpolymorphisms, such as GSTM1 and GCLM may modify MeHg metabolism and Hg-related antioxidant effects.”

“BACKGROUND:

Administration of mercury at nontoxic doses induces systemic autoimmune disease in Brown Norway (BN) rats. The pathogenesis of lupus-like oral mucosal lesion by mercury-induced autoimmunity is still unclear, even though the oral mucosa is observed to be commonly affected in mercury-treated BN rats. In this study, we investigated the immunopathology of lupus-like oral mucosal lesions in a model of mercury-induced systemic autoimmunity.

METHODS:

Brown Norway male rats were injected subcutaneously with either phosphate-buffered saline (control) or mercury at a dose of 1.0 mg per kilogram of body weight on days 0, 3, 5, and 7. Blood, kidney, and tongue samples were taken at various timepoints for evaluation by immunohistochemistry, RT-PCR, and lupus band test (LBT).

RESULTS:

Oral mucosal lesions were classified according to three consecutive temporal phases on the basis of infiltration of immunocompetent cells as follows: (phase I) infiltration of MHC class II+ dendritic cells (DC) and macrophages; (phase II) addition of ED1+ macrophage infiltrates; and (phase III) focal infiltration of pan T cells following increased infiltration of DC and macrophages. Dense infiltration of DC and macrophages was observed in the basement membrane (BM) zone of the oral epithelium. Tissue expression of IL-4 mRNA was detected in early lesions (phase I), suggesting that locally produced IL-4 may be responsible for Th2-mediated immune response. A linear and continuous smooth pattern of fluorescence was observed in the oral epithelial BM in addition to renal glomeruli, indicating immune complex deposits.

CONCLUSIONS:

Local autoimmune responses are involved in the pathogenesis of mercury-induced lupus-like lesions of the oral mucosa.”

OBJECTIVES:
To evaluate the effects of 3 T magnetic field on microleakage of amalgam restorations containing three different types of silver (Ag).

METHODS:
60 extracted teeth were restored with three different types of amalgam filling materials. Restored teeth were sectioned mesiodistally and divided into experimental and control groups. Experimental groups were exposed to a magnetic field of 3 T for 20 min. All samples were plunged into 2% basic fuchsin solution and examined under a digital microscope by three different observers with regard to microleakage.

RESULTS:
Statistical analysis showed significant differences in microleakage between the groups exposed to MRI and controls, whereas differences in microleakage between amalgam types were insignificant.

CONCLUSIONS:
The primary risk of MRI systems arises from the effects of its strong magnetic field on objects containing ferromagnetic materials. An MRI of 1.5 T is known to be safe for amalgam restorations. However, our research indicates that MRI is not completely devoid of any effects on amalgam restorations.

“Various forms of mercury possess different rates of absorption, metabolism and excretion, and consequently, toxicity. Methylmercury (MeHg) is a highly neurotoxic organic mercurial. Human exposure is mostly due to ingestion of contaminated fish. Ethylmercury (EtHg), another organic mercury compound, has received significant toxicological attention due to its presence in thimerosal-containing vaccines. This study was designed to compare the toxicities induced by MeHg and EtHg, as well as by their complexes with cysteine (MeHg-S-Cys and EtHg-S-Cys) in the C6 rat glioma cell line. MeHg and EtHg caused significant (p<0.0001) decreases in cellular viability when cells were treated during 30min with each mercurial following by a washing period of 24h (EC50 values of 4.83 and 5.05?M, respectively). Significant cytotoxicity (p<0.0001) was also observed when cells were treated under the same conditions with MeHg-S-Cys and EtHg-S-Cys, but the respective EC50 values were significantly increased (11.2 and 9.37?M). l-Methionine, a substrate for the l-type neutral amino acid carrier transport (LAT) system, significantly protected against the toxicities induced by both complexes (MeHg-S-Cys and EtHg-S-Cys). However, no protective effects of l-methionine were observed against MeHg and EtHg toxicities. Corroborating these findings, l-methionine significantly decreased mercurial uptake when cells were exposed to MeHg-S-Cys (p=0.028) and EtHg-S-Cys (p=0.023), but not to MeHg and EtHg. These results indicate that the uptake of MeHg-S-Cys and EtHg-S-Cys into C6 cells is mediated, at least in part, through the LAT system, but MeHg and EtHg enter C6 cells by mechanisms other than LAT system.”