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 (Ecorr) 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 Ecorr values underscore the protective effect of copper against corrosion in
multispecies biofilm environments.