PubMed · 6939786
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F Goldberg. 1981. Relation between corroded silver points and endodontic failures.. https://doi.org/10.1016/s0099-2399(81)80179-3
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The first metal-on-metal artificial hip joints of the sixties (for example that of Mckee, Norwich) were soon replaced by models with polyethylene acetabular cups because of several shortcomings. 20 years later, however, a few patients were seen where such metal-to-metal joints still performed very well. Closer investigations revealed that with improved machining and a more perfect fit the failures of the first series could be eliminated and that these models were much less prone to wear than the ones using polyethylene. The author has developed and inserted such new prostheses, with good success so far.
Discoloring and layers on bands and restorations during fixed orthodontic therapy are well known clinical phenomenon. Because of the complexity of etiological factors an in-vitro model was used in this study. Aim of the study was to examine the amounts and sort of metals which are dissolved. Therefore, respectively 25 normed MOD-cavities in Frasaco-teeth were filled with a non-gamma-2-amalgam (Amalcap plus, Vivadent) and condensed manually or mechanically. In addition, ten crowns of a high golden (Maingold SG, Heraeus) as well as a palladium basis alloy (Albabond A, Heraeus) were casted. Then they were banded with stainless steel bands (Dentaurum) and cemented with a glass ionomer cement (Ketac Cem, Espe). The probes were given into a 0.1 molar lactic acid for seven days at 37 degrees C. Using ICP (ion coupled plasma) analysis the corrosion solution was examined for elements. High levels of Zn- and Al-ion contents were found, which are components of the used cements. The filling materials themselves mainly set free small amounts of Ag, Sn or Cu. The steel band released Fe, Cr, Ni and Ti. The combination of filling material and band resulted in a higher release of most ions.
Microcracks, flaws, and voids inside a metal-porcelain restoration may cause the restoration to fracture in service. Such cracks result in the concentration of stresses. The dynamic nature of the stresses due to mastication promotes crack growth. In addition, corrosive components of the oral environment enhance the growth rate. In the present investigation, fracture mechanics has been used to analyze the in vitro resistance to fracture of the porcelain-fused-to-metal restoration. The risk of a clinical failure of porcelain-fused-to-metal decreases with enlarged crack resistance (increasing work of fracture). The work of fracture represents an average of the energy for initiation and propagation of a crack through the interface separating porcelain and metal. This work also indicates a material's ability to stop a crack once it is moving. This study utilized the three-point bending test for the crack resistance measurement, and investigated one palladium and five base metal alloys. Corrosive components of the oral environment and the details of firing were of crucial importance for long-term bond stability.