Do oral biofilms influence the wear and corrosion behavior of titanium?

Abstract

The simultaneous corrosion-wear of titanium isknown as tribocorrosion and is a detrimental process that can occur in the oral cavity. Actually, the process has been investigated in simulated physiological solutions although the role of biofilms on it is not yet reported. The main aim of this work is to study the simultaneous wear-corrosion of titanium in presence of biofilms composed of Streptococcus mutans and Candida albicans. Both organisms were separately grown in specific growth media, and then mixed in a medium supplemented with high sucrose concentration. Corrosion and tribocorrosion tests were performed after 48 h and 216 h of biofilm growth. Electrochemical corrosion tests indicated a decrease of the corrosion resistance of titanium in presence of biofilms although the titanium oxide film presented characteristics of a compact oxide film. While the open circuit potential of titanium indicated a tendency to corrosion in the presence of biofilms, tribocorrosion tests revealed a low friction in the case of titanium covered with biofilms. The properties of biofilms are similar to those of lubricant agents used to decrease the wear rate of materials. However, the lowering of pH promoted by microbial species, can lead to corrosion of titanium-based oral rehabilitation systems.