The corrosive effects of artificial saliva on cast and rapid manufacture-produced cobalt chromium alloys

Purpose - Rapid manufacture-produced cobalt chromium alloys are beginning to be used in dentistry but there are few published results relating to their properties. The purpose of this paper is to determine the corrosion resistance of a rapid manufacture-produced dental alloy and compare it to a standard dental casting alloy. Design/methodology/approach - In accordance with ISO 22674, ten samples of each alloy were fabricated in approximately 45?mm×10? mm×2?mm rectangular prisms, a sample number in excess of the standard requirements. The groups were further divided into those with highly polished surfaces and those with electrobrightened surfaces. Each sample was immersed in artificial saliva, suspended by a nylon thread for 42 days at 37°C. Readings for cobalt, chromium and molybdenum ions released into solutions were obtained using an atomic absorption spectrometer at 1, 4, 7, 14, 21, 28, 35, and 42 day intervals at a detection limit of one part per million. Findings - Ion release of cobalt, chromium and molybdenum was well within the threshold prescribed by the standard. The alloys were safe for use as dental devices with respect to the above metals. The rapid manufacture alloy however performed better. In addition the data indicated that for both alloys, there was no discernable difference between a polished and an electrobrightened surface. Originality/value - The rapid manufacture alloy studied shows a safe level of corrosion resistance with respect to cobalt, chromium and molybdenum according to ISO definitions. Further biocompatibility tests are recommended.