Biocompatibility of dental casting alloys: A review

Statement of problem. Dental casting alloys are widely used in applications that place them into contact with oral tissues for many years. With the de velopment of new dental alloys over the past 15 years, many questions remai n about their biologic safety. Practitioners must choose among hundreds of alloy compositions, often without regard to biologic properties. Purpose. This article is an evidence-based tutorial for clinicians. Concept s and current issues relevant to the biologic effects of dental castings al loys are presented. Summary. The single most relevant property of a casting alloy to its biolog ic safety is its corrosion. Sytemic and local toxicity, allergy, and carcin ogenicity all result from elements in the alloy being released into the mou th during corrosion. Little evidence supports concerns of casting alloys ca using systemic toxicity. The occurrence of local toxic effects (adjacent to the alloy) is not well documented, but is a higher risk, primarily because local tissues are exposed to much higher concentrations of released metal ions. Several elements such as nickel and cobalt have relatively high poten tial to cause allergy but the true risk of using alloys containing these el ements remains undefined. Prudence dictates that alloys containing these el ements be avoided if possible. Several elements in casting alloys are known mutagens, and a few such as beryllium and cadmium are known carcinogens in different chemical forms. Despite these facts, carcinogenic effects from d ental casting alloys have not been demonstrated. Prudent practitioners shou ld avoid alloys containing these known carcinogens. Conclusion. To minimize biologic risks, dentists should select alloys that have the lowest release of elements (lowest corrosion). This goal can be ac hieved by using high-noble or noble alloys with single-phase microstructure s. However, there are exceptions to this generality: and selection of an al loy should be made on a case-by-case basis using corrosion and biologic dat a from dental manufacturers.