The IdentAlloy certification program was developed to make dentists and patients more aware of the composition of dental alloys.
List Of Alloys And Their Composition And Uses Files Download As PDFFrom: Encyclopedia of Materials: Science and Technology, 2002 Related terms: Leucite Biocompatibility Alloy Chromium Cobalt Indium Palladium Metal Ion View all Topics Download as PDF Set alert About this page Dental Materials: Biocompatibility R.
Messer, J. Wataha, in Encyclopedia of Materials: Science and Technology, 2002 1.1 Compositions, Forms, and Uses Dental alloys are diverse in composition, ranging from nearly pure gold and traditional gold-based alloys to alloys based on silver, palladium, nickel, cobalt, iron, titanium, tin, and other metals ( Table 1 ). The types of dental alloys available to the dental practitioner have increased dramatically since the start of the 1980s in response to changes in the market price of gold and palladium, the need for increasingly specialized physical properties, and an increase awareness of biological properties. Dental alloys are commonly custom precision-cast for restoration of missing tooth structure, but wrought forms (shaped by the manufacturer or the clinician) are also common, and dental amalgam is an alloy that forms in situ in a tooth cavity preparation after mixing of a AgSn alloy with mercury. Table 1. Common types of alloys in dentistry and their major component elements. Because of these many uses, the environments in which the alloys must function are diverse, as are the physical requirements of the alloys. For example, an orthodontic wire is required to have a relatively high flexibility (a low modulus) and the ability to be bent and shaped. However, the alloy for a dental restoration should have almost no flexibility (a high modulus) and be hard and difficult to deform. Alloys may be present for only a few minutes, as in the case of an endodontic file, or may be permanently cemented for decades. The biological requirements for each of these uses may vary considerably. Figure 1. Intraoral photographs of (top) multiple types of alloys used in dental restorations and (bottom) site of a dental implant (implanted into bone, but protruding through the soft tissue) immediately post-surgery (photos courtesy of Dr. Steve Nelson, Medical College of Georgia, USA). List Of Alloys And Their Composition And Uses Files Full Chapter URLView chapter Purchase book Read full chapter URL: Restorative Materials In Craigs Restorative Dental Materials (Fourteenth Edition), 2019 Biocompatibility The biocompatibility of noble dental alloys is equally important as other physical or chemical properties. The biocompatibility of noble dental alloys is primarily related to elemental release from these alloys (i.e., their corrosion). Thus any toxic, allergic, or other adverse biological response is primarily influenced by elements released from these alloys into the oral cavity. The biological response is also influenced significantly by exactly which elements are released, their concentrations, and duration of exposure to oral tissues. For example, the short-term (more than 1 to 2 days) release of zinc may not be significant biologically, but longer-term (more than 2 to 3 years) release might have more significant effects. Similarly, equivalent amounts (in moles) of zinc, copper, or silver will have quite different biological effects, because each of the elements is unique in its interactions with tissues. However, in general, several principles apply to alloy biocompatibility. The elemental release from noble alloys is not proportional to alloy composition, but rather is influenced by the numbers and types of phases in the alloy microstructure and the composition of the phases. In general, multiple-phase alloys release more atoms than single-phase alloys. Some elements, such as copper, zinc, silver, cadmium, and nickel, are inherently more prone to be released from dental alloys than others, such as gold, palladium, platinum, and indium. Alloys with high noble-metal content generally release less atoms than alloys with little or no noble-metal content. However, the only reliable way to assess elemental release is by direct measurement, because there are exceptions to each of the generalizations just mentioned. Similarly, it is difficult to predict, even knowing the elemental release from an alloy, what the biological response to the alloy will be. Thus the only reliable way is to measure the biological response directly, either in vitro, in animals, or in humans (see Chapter 6 ). It is important to also remember that combinations of alloys used in the mouth may alter their corrosion and biocompatibility.
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