This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of fish have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an "element of mystery."

The Toxicology of Mercury and Its Chemical Compounds

http://www.ibmc.up.pt/projectos/FJMonteiro/Bonamidi%20Project/References%20Bonamidi/Denry%20-%20State%20of%20the%20art%20zirconia%20dental%20applications.pdf

State of the art of zirconia for dental applications

ercury has been used commercially and medically for centuries. In the past it was a common constituent of many medications. It is still used in hospitals in thermometers and blood-pressure cuffs and commercially in batteries, switches, and fluorescent light bulbs. Large quantities of metallic mercury are employed as electrodes in the electrolytic production of chlorine and sodium hydroxide from saline. These uses still give rise to accidental and occupational exposures. 1 Today, however, exposure of the general population comes from three major sources: fish consumption, dental amalgams, and vaccines. Each has its own characteristic form of mercury and distinctive toxicologic profile and clinical symptoms. Dental amalgams emit mercury vapor that is inhaled and absorbed into the bloodstream. Dentists and anyone with an amalgam filling are exposed to this form of mercury. Liquid metallic mercury (quicksilver) still finds its way into homes, causing a risk of poisoning from the vapor and creating major cleanup costs. Humans are also exposed to two distinct but related organic forms, methyl mercury (CH 3 Hg + ) and ethyl mercury (CH 3 CH 2 Hg + ). Fish are the main if not the only source of methyl mercury, since it is no longer used as a fungicide. In many countries, babies are exposed to ethyl mercury through vaccination, since this form is the active ingredient of the preservative thimerosal used in vaccines. Whereas removal of certain forms of mercury, such as that in blood-pressure cuffs, will not cause increased health risks, removal of each of the three major sources described in this article entails health risks and thus poses a dilemma to the health professional. Exposure to mercury from dental amalgams and fish consumption has been a concern for decades, but the possible risk associated with thimerosal is a much newer concern. These fears have been heightened by a recent recommendation by the Environmental Protection Agency (EPA) that the allowable or safe daily intake of methyl mercury be reduced from 0.5 µg of mercury per kilogram of body weight per day, the threshold established by the World Health Organization in 1978, 2 to 0.1 µg of mercury per kilogram per day. 3 Table 1 summarizes the clinical toxicologic features of mercury vapor and methyl and ethyl mercury. It also includes data on inorganic divalent mercury, since this is believed to be the toxic species produced in tissues after inhalation of the vapor. 5 It is also responsible for kidney damage after exposure to ethyl mercury, since ethyl mercury is rapidly converted to the inorganic form. 13 Inorganic mercury as both mercuric and mercurous salts was also the chief cause of acrodynia, a childhood disease that is now mainly of historical interest. 14 The clinical symptoms of acrodynia consist of painful, red, swollen fingers and toes in association with photophobia, irritability, asthenia, and hypertension. It is believed to be a hypersensitivity reaction. m

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The toxicology of mercury--current exposures and clinical manifestations.

An overview of zirconia ceramics: Basic properties and clinical applications

Current ceramic materials offer preferred optical properties for highly esthetic restorations. The inherent brittleness of some ceramic materials, specific treatment modalities, and certain clinical situations require resin bonding of the completed ceramic restoration to the supporting tooth structures for long-term clinical success. This article presents a literature review on the resin bond to dental ceramics. A PubMed database search was conducted for in vitro studies pertaining to the resin bond to ceramic materials. The search was limited to peer-reviewed articles published in English between 1966 and 2001. Although the resin bond to silica-based ceramics is well researched and documented, few in vitro studies on the resin bond to high-strength ceramic materials were identified. Available data suggest that resin bonding to these materials is less predictable and requires substantially different bonding methods than to silica-based ceramics. Further in vitro studies, as well as controlled clinical trials, are needed.

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Resin-ceramic bonding: a review of the literature.

Fracture resistance of yttrium oxide partially-stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing.

A meta-analytic technique was used to estimate the survival of implants supporting bridges or single crowns in partially edentulous patients. A survey of the literature revealed 66 studies, published between 1986 and 1996. Nine studies on single implants and 10 studies on fixed partial dentures met the inclusion criteria for the meta-analysis. Data from a total of 2686 implants, 570 single crowns (SC) and 2116 in fixed partial dentures (FPD), were analyzed. In order to calculate annual survival rates for individual studies a life-table analysis was conducted. Maximum follow-up time ranged between 1 and 8 years. After 1 year the success rate was calculated to be at least 85.7% for FPD and 97.2% for SC. When the results from the FPD studies were pooled the survival rate was 93.6% after 6-7 years. The corresponding value for SC was 97.5%.

A meta-analysis of implants in partial edentulism.

Bond Strength of Composite Luting Cement to Zirconia Ceramic Surfaces

Purpose: The aim of this prospective study was to evaluate the clinical performance of fully sintered hot isostatic pressed yttria-partially-stabilized zirconia (Denzir) 3-unit fixed partial dentur ...

Five-year clinical prospective evaluation of zirconia-based Denzir 3-unit FPDs

Four inlay systems--gold, Cerec, Mirage, and Empress inlays--were evaluated for their adaptation to stone die and clinically to the tooth by means of a replica technique. Twenty inlays of each system were placed on premolars and molars in the lower jaw. A microscope was used to measure the adaptation at the approximal margin, at the inner axial wall, and at the occlusal cavosurface area. An overall better fit was observed for the gold inlays than for the ceramic inlays. When the different measuring locations were compared, a better fit was found for the occlusal area. The greatest discrepancies were recorded for the Cerec inlays, whereas the Mirage and Empress inlays were comparable.

Margareta Molin

Papers

Fracture resistance of yttrium oxide partially-stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing.

A meta-analysis of implants in partial edentulism.

Bond Strength of Composite Luting Cement to Zirconia Ceramic Surfaces

Five-year clinical prospective evaluation of zirconia-based Denzir 3-unit FPDs

The fit of gold inlays and three ceramic inlay systems: A clinical and in vitro study