Method: Ti6Al4V and CoCrMo alloy discs (n=3/group) were tested under free potential, potentiostatic, and potentiodynamic conditions, using a custom-made tribocorrosion apparatus that simulated the TMJ environment. Sliding duration (1800 cycles), frequency (1.0Hz) and load (16N) parameters mimicked the daily mastication process. Synovial-like fluid (Bovine Calf Serum, pH=7.6) was used to simulate the in-vivo environment. Electrochemical impedance spectroscopy was conducted before and after the experiment to compare the changes in corrosion kinetics as a function of mastication. Surface roughness was measured using white-light interferometry. Finally, total weight loss and roughness values were calculated. Mann-Whitney U test was used to determine statistical significance (p<0.05).
Result: Under static conditions, Ti6Al4V demonstrated a lower corrosion rate compared to CoCrMo (Icorr=2.01x10-6A/cm2 vs. 8.83x10-9A/cm2 respectively; p<0.0001) and enhanced corrosion kinetics (Rp=3.60x106ohms vs. 5.13x105ohms respectively; p<0.05). In contrast, under sliding conditions, Ti6Al4V showed a higher weight loss from wear compared to CoCrMo (Kw=2.86µg vs. 325.5µg respectively; p<0.0001), a higher weight loss from corrosion (Kc=0.93µg vs. 29.70µg respectively; p<0.0001) and a higher weight loss from the combined effects of wear and corrosion (Kwc=3.80µg vs. 355.10µg respectively; p<0.0001). White-light interferometry measurements demonstrated a greater difference in surface roughness in Ti6Al4V compared to CoCrMo after sliding (Ra=297.78nm vs. 69.52nm respectively; p<0.01).
Conclusion: Under static conditions, Ti6Al4V offers superior corrosion behavior compared to CoCrMo; however, under sliding conditions, CoCrMo offers superior corrosion and biomechanical properties.