Tribocorrosive behaviour of commonly used temporomandibular implants in a synovial fluid-like environment: Ti–6Al–4V and CoCrMo

The temporomandibular joint implant metal alloys, Ti6Al4V and CoCrMo, ( n = 3/group) were tested under free-potential and potentiostatic conditions using a custom-made tribocorrosion apparatus. Sliding duration (1800 cycles), frequency (1.0 Hz) and load (16 N) mimicked the daily mastication process. Synovial-like fluid (bovine calf serum, pH = 7.6 at 37 °C) was used to simulate the in vivo environment. Changes in friction coefficient were monitored throughout the sliding process. Changes in surface topography, total weight loss and roughness values were calculated using scanning electron microscopy and white-light interferometry. Finally, statistical analyses were performed using paired t -tests to determine significance between regions within each metal type and also independent sample t -tests to determine statistical significance between metal alloy types. Ti6Al4V demonstrated a greater decrease of potential than CoCrMo, a higher weight loss from wear ( K w = 257.8 versus 2.62 µ g; p < 0.0001), a higher weight loss from corrosion ( K c = 17.44 versus 0.14 µ g; p < 0.0001) and a higher weight loss from the combined effects of wear and corrosion ( K wc = 275.28 versus 2.76 µ g; p < 0.0001). White-light interferometry measurements demonstrated a greater difference in surface roughness inside the wear region in Ti6Al4V than CoCrMo after the sliding ( R a = 323.80 versus 70.74 nm; p < 0.0001). In conclusion, CoCrMo alloy shows superior anti-corrosive and biomechanical properties.