Multi-Species Biofilm Interactions and Their Impact on the Biocorrosion of Copper-Coated CoCr Alloys in Dental Application

Biocorrosion of materials used in dental restorations is a complex process involving various bacterial species that coexist as biofilms. Since copper possesses excellent antibacterial properties, it could help minimize this problem. The aim of this study is to assess the antibiofilm characteristics and corrosion resistance of CoCr and copper-coated CoCr alloys in a multispecies biofilm model. CoCr alloys and CoCr coated with copper (CoCr/Cu) using Physical Vapor Deposition (PVD) were investigated. The samples were incubated in media with and without a multispecies biofilm for 24 h and for 15 days. Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) were used to assess the corrosion behavior of the samples. Scanning Electron Microscopy (SEM) was utilized to observe the growth of multispecies biofilms and the type of corrosion. The Mann–Whitney U test was employed to examine corrosion results, with significant differences defined as p < 0.05. CoCr/Cu alloys demonstrated superior corrosion resistance at 24 h and 15 days in the presence of biofilm compared to those without coating. No differences were observed in multispecies biofilm formation at 24 h. The study demonstrates that copper-coated CoCr alloys (CoCr/Cu) exhibit a more positive corrosion potential (E_corr) compared to uncoated CoCr alloys, both in the presence and absence of multispecies biofilm (BP) at 24 h and 15 days. After 15 days, the potential of CoCr/Cu with BP was −0.144 V, compared to −0.252 V for uncoated CoCr. These significant differences in E_corr values underscore the protective effect of copper against corrosion in multispecies biofilm environments.