CHARACTERIZATION OF NOBLE-METAL IMPLANT CYLINDERS - AS-RECEIVED CYLINDERS AND CAST INTERFACES WITH NOBLE-METAL ALLOYS

A common procedure in the fabrication of implant prostheses is the use of premade wrought cylinders in cast frameworks. Although manufacture rs outline some precautions in the use of these components, detailed i nformation about the metal interface between cylinders and cast alloys is lacking. This article, following a previous report that compared t itanium-based implant cylinders used with two different classes of cas t alloys, compares conventional noble metal cylinders from three diffe rent manufacturers combined with these two classes of cast noble alloy s. Analysis of the as-received cylinders revealed that the implant cyl inders as a group are predominantly composed of metals commonly found in noble dental alloys, namely, platinum, palladium, gold, and silver. The interfaces created by casting both high-fusing and low-fusing all oys around the cylinders exhibited a general elemental concentration v ariability compared with the bulk alloy regions, but continuous concen trations for shared elements suggested alloy-cylinder compatibility. V ickers hardness values, which ranged from 212 to 276 for the as-receiv ed cylinders, decreased from 12% to 43% for the various cylinders afte r casting. This study suggests characteristics of an ideal east interf ace that include maintenance of the cylinder and casting alloy microst ructures up to the interface, absence of interfacial reaction regions, lack of porosity created by volatilization of components from either alloy or the casting process, and sufficient strength to maintain anti cipated loads.