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The aim of this study was to investigate the effect of repeated casting and heat treatment on the corrosion resistance of a commercial Ag-Pd-Cu-Au alloy as evaluated by electrochemical techniques. After repeated casting, the fifth cast of the Ag-Pd-Cu-Au alloy exhibited dramatic degradation of properties, although upon heat treatment, this corrosion resistance did improve. Despite the improvement by heat treatment, after five castings, this alloy may not have satisfactory hardness for clinical use. These results of this study demonstrate that, up to the fourth cast and heat treatment, the Ag-Pd-Cu-Au alloy has acceptable corrosion resistance and hardness.

Although most cases of malignant mesothelioma of the pleura are caused by one or more readily recognized sources of exposure to asbestos, cases of the disease with more occult exposure occur, especially since asbestos has been used in over 3,000 products. Dental lining tape contained asbestos from the 1930s until at least the 1970s and was used in the lost wax method of casting crowns, bridges, and other metal dental prosthetic devices. We report six cases of pathology-verified malignant mesothelioma, mostly among dentists, following exposure to airborne dust from asbestos dental tape, which resulted in asbestos tort litigation. According to evidence available at present, chrysotile asbestos was the type of asbestos used in dental tape in the past in the United States, and the described cases followed relatively brief and intermittent exposure to this type of asbestos. These cases underscore the need for comprehensive exposure histories to determine exposure scenarios. Am. J. Ind. Med. 60:437-442, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

Side-effects from dental materials are a minor problem, but should be recognized. In recent questionnaire surveys about side-effects, the incidence was estimated to be 1:300 in periodontics and 1:2600 in pedodontics. None of these reactions was related to dental casting alloys. In prosthodontics, the incidence was calculated to be about 1:400, and about 27% were related to base-metal alloys for removable partial dentures (cobalt, chromium, nickel) and to noble/gold-based alloys for porcelain-fused-to-metal restorations. The complaints consisted of intra-oral reactions (such as redness, swelling, and pain of the oral mucosa and lips), oral/gingival lichenoid reactions, and a few instances of systemic reactions. In orthodontics, the incidence was 1:100, and most reactions (85%) were related to metal parts of the extra-oral anchorage devices. Even though the extensive use of base-metal alloys has been of major concern to the dental profession, relatively few case reports substantiate this concern. Allergy to gold-based dental restorations has been more commonly reported. Palladium-based alloys have been associated with several cases of stomatitis and oral lichenoid reactions. Palladium allergy seems to occur mainly in patients who are very sensitive to nickel. All casting alloys, except titanium, seem to have a potential for eliciting adverse reactions in individual hypersensitive patients. Tolerance induction may be a possible benefit of the use of intra-orally placed alloys. In non-sensitized individuals, oral antigenic contacts to nickel and chromium may induce tolerance rather than sensitization. A variety of systemic diseases and reactions has been claimed to be caused by dental materials. The claims are generally poorly documented.

258 units of fixed crowns and inlays, produced with the powder metallurgic Degusint-System (Degussa), were clinically evaluated 6 and 12 months after insertion. Periodontal examinations, especially of the crevicular fluid flow, failed to show higher amounts of marginal inflammation due to the subgingival localization of the margins of fixed sintermetallic restorations compared with reference teeth of the same individual. Plaque accumulations during the wearing period were quite the same as those observed with crowns.

The cytotoxic potentials of three Ni-Cr based alloys and an Fe-Cr based alloy were assessed. In tissue culture, casting of all four test materials and powders of the Fe-Cr based material did not elicit adverse cellular changes. However, cultures containing Ni-Cr powders showed prominent zones of lysis and cell alteration. The cytotoxic potential of products obtained from the surfaces of casting alloys may offer an expedient means for estimation of long-term clinical toxicity.