Clinical and laboratory study of corrosion resistance of a base dental alloy for selective laser melting

Abstract

Introduction: CAD/CAM technologies are becoming widely used for the production of metal ceramic dental restorations. Powder Co-based alloys are developed for selective laser melting. The corrosion resistance of the dental alloy affects the biocompatibility, functional suitability, and longevity of the prosthetic restoration. Aim: The aim of this study was to evaluate and compare the corrosion resistance of a cobalt-chromium dental alloy for porcelain-fused-to-metal (PFM) crowns produced for selective laser melting technique in clinical and laboratory conditions. Materials and methods: PFM crowns were made for 35 patients using CAD/CAM technology. The metal copings of the crowns were made of the EOS CobaltChrome SP2 alloy (EOS, Germany). Eocp measurements were conducted 2 hours and 7 days after fixing the restorations in oral cavity. The digital files of patients’ designed copings were used for the production of another 35 specimens, which were placed in artificial saliva. Eocp measurements were conducted after the same periods. Results: In vitro studies showed high corrosion resistance after the short 2-hour stay. After 7 days in artificial saliva, the corrosion resistance became even higher probably due to strong passivation. In clinical conditions, Eocp values were slightly higher than the normal range 2 hours after fixing the crowns. Seven days after fixing, the Eocp values showed a decrease of corrosion resistance of the PFM crowns. The cause of the decrease may be interaction with other metal objects or specific conditions of the oral cavity. Conclusions: The investigated alloy showed high corrosion resistance in in vitro settings. Clinical research revealed that PFM crowns had lower corrosion resistance. Further observation and research are required.