Mercury

“The ADA owes no legal duty of care to protect the public from allegedly dangerous products used by dentists. The ADA did not manufacture, design, supply or install the mercury-containing amalgams.  The ADA does not control those who do.  The ADA’s only alleged involvement in the product was to provide information regarding its use.  Dissemination of information relating to the practice of dentistry does not create a duty of care to protect the public from potential injury.”

“The multistage case-detection approach achieved reliable and valid diagnoses of AD with high apparent sensitivity but substantial attrition after initial screening. Genetic influences in AD at this age are limited, except among homozygotes for allele epsilon 4 at APOE. Subjects with early-onset AD who lack the epsilon 4 allele are not rare, and their condition appears to have little genetic influence. They should be ideal for studies on environmental cause of AD.”

“Dental amalgam, which is composed of metallic mercury, silver, copper, tin, and zinc, has been the subject of intermittent controversy since it was introduced into dental practice 150 years ago. When they interact with saliva, amalgam fillings will slowly corrode…”

“Although mercury exposure levels among dentists have been steadily decreasing, occupational mercury exposure among dental professionals continues to be a matter of interest. This study examined personal professional and office characteristics of dentists to determine which factors contribute most to exposure. The resulting information will help dental professionals change their practices to minimize unnecessary exposure to elemental mercury.”

“Oral lichenoid lesions (OLL) or lichen-planus-like lesions are often idiopathic. Our aim was to determine whether OLL can be caused by allergy to mercury in amalgam fillings, and whether resolution of OLL occurs after replacement of amalgam with other dental fillings. Patients with only OLL (except for 1 case with cutaneous lichen planus) referred for patch testing during 1985-1994 to the Contact and Occupational Dermatitis Clinic of the Skin & Cancer Foundation, Darlinghurst, were reviewed. Patch tests were performed with 1% mercury, 1% ammoniated mercury, 0.1% thimerosal, 0.1% mercuric chloride, 0.05% phenylmercuric nitrate and an amalgam disc, using Finn Chambers occluded for 2 days, 19 patients (17 women and 2 men; age range: 28-72 years) had OLL in close contact with amalgam fillings and showed positive patch test reactions to mercury compounds, 16 out of 19 patients had their amalgam fillings replaced. In 13 patients, the OLL healed. 1 patient had marked improvement. 1 patient had no improvement and developed multiple oral squamous cell carcinoma. In conclusion, OLL can be caused by allergy to mercury in amalgam fillings. Replacement of amalgam with other dental fillings usually results in resolution of OLL and is recommended for cases with positive patch test reactions to mercury compounds.”

“Chronic exposure to inorganic mercury can cause kidney injury. Evidence gained from occupational medicine indicates that individuals who are exposed to only environmental sources, including amalgam tooth fillings, are at very little risk. Animal experiments, however, have revealed glomerular lesions of immunologic origin after low-dose exposure to inorganic mercury. In this study, the association between the number of amalgam tooth surfaces, urinary mercury, and proteinuria was explored in a sample of 48 randomly selected, apparently healthy male students who were 17-22 y of age. Presence of any of the following proteins in two separate urine samples was considered to be potentially indicative of any tubular and/or glomerular lesion: albumin, alpha-1-microglobulin (HC-protein), kappa and lambda light chains, and N-acetyl-beta-D-glucosaminidase. No significant relationship was found between any of the proteins and amalgam or urinary mercury. The results of this study did not suggest that amalgam fillings cause kidney dysfunction in humans.”

“The regulation of most biochemical pathways and transport systems involves protein-nucleotide interactions. In general, nucleotides regulate the properties of proteins by contributing free energy through tvm pathways. The first is by binding causing conformation changes that affect activities.”

“174 patients referred to the Department of Oral and Maxillofacial Surgery, Central Hospital, Karlstad, Sweden during 1987 to 1989 for lichenoid lesions and evaluation of a possible connection with amalgam restorations were invited to a clinical re-examination. 159 of the patients were re-examined with the purpose of evaluating the long-term effect upon performed substitution therapy. Partial or total removal of amalgam had been recommended according to a set of given criteria. The re-examination showed that 62 patients had performed partial and 69 patients total removal of amalgam fillings. 28 patients had not performed any substitution therapy. There was a difference between recommended and performed therapy. The results demonstrated that 92% of patients with lichenoid lesions only in contact with amalgam fillings healed or improved clinically following removal of amalgam. No statistical difference was found in healing between patients who only removed fillings in contact and those who had removed all amalgam restorations. More than 60% of buccal lichenoid lesions without contact with amalgam at time of referral disappeared following amalgam substitution. Gingival lichenoid lesions did not respond to substitution of amalgam to another material. 3 out of 17 patch-tested patients demonstrated a hypersensitivity reaction to mercury. All lichenoid lesions in these patients healed following total substitution. Partial or total removal of amalgam fillings was also performed on 10 patients with completely negative patch-tests. 6 out of these patients demonstrated complete healing of their lichenoid reactions at re-examination.”(ABSTRACT TRUNCATED AT 250 WORDS)

“The release of mercury vapor from class I amalgam restorations prepared in human molar teeth was studied during chewing simulations in an artificial mouth of a bi-axial servo-hydraulic mechanical test system. So that the total mercury released from the restoration over a fixed time could be determined, a closed chamber surrounded the envelope of chewing motion. In addition, the influence of sampling frequency on mercury release was corrected by the use of different sampling frequencies over a fixed time interval of mercury release measurement and extrapolation to zero sampling time. Thus, a combination of a closed environment and an extrapolation method to determine the mercury release under continuous sampling was used to determine the mercury released under normal breathing conditions. The measured mercury release rate data were used to calculate the potential daily mercury dose in a patient due to a single amalgam restoration, following the method previously outlined by Berglund. The mercury release from both a conventional and a high-copper amalgam was evaluated at different age intervals after the restoration was placed in the teeth. The results show that while the age of the amalgam and the amalgam type influence the extent of mercury release during the initial non-steady-state conditions, the steady-state value of mercury daily dose due to a single amalgam filling is 0.03 micrograms/day, which is well below the calculated threshold-limiting value (TLV) of 82.29 micrograms/day considered dangerous for occupational exposure in the United States.”

“The thiol-oxidizing reagent, thimerosal, has been shown to increase the intracellular Ca2+ concentration, to induce Ca2+ spikes in several cell types, and to increase the sensitivity of intracellular Ca2+ stores to inositol 1,4,5-trisphosphate. Ryanodine-sensitive stores have also been implicated in the generation of Ca2+ oscillations induced by the addition of thimerosal. Here we report that micromolar concentrations of thimerosal stimulate Ca2+ release from skeletal muscle sarcoplasmic reticulum vesicles, inhibit high affinity [3H]ryanodine binding, and modify the channel activity of the reconstituted Ca2+ release protein. Thimerosal inhibits ryanodine binding by decreasing the binding capacity (Bmax) but does not affect the binding affinity or the dissociation rate of bound ryanodine. Single channel reconstitution experiments show that thimerosal (100-200 microM) stimulates single channel activity without modifying channel conductance. The thimerosal-stimulated channel is not inhibited by heparin. Furthermore, a Ca(2+)-stimulated channel is first activated and then inhibited in a time-dependent fashion by high concentrations of thimerosal (1 mM). Once inactivated, the channel cannot be reactivated by addition of either Ca2+ or ATP.”