Fretting-corrosion behavior on dental implant connection in human saliva.

Fretting-corrosion has been pointed out as failure mechanism in dental implants between the implant part and the abutment. Depending on countries, surgical habits, 4 combinations of materials, are well used. The behavior of fretting corrosion of these four combinations of materials have been highlighted: pure titanium (Ti-grade 4) against titanium alloy (Ti-6Al-4V); titanium alloy (Ti-6Al-4V); against titanium alloy (Ti-6Al-4V); pure titanium against zirconia stabilized with Yttria (Y-TZP) and titanium alloy (Ti-6Al-4V) against zirconia (Y-TZP). Around 100 MPa of contact pressure, approx. the maximal mechanical stresses in dental assembly, after 16 h of fretting corrosion (± 40 µm, displacement) solicitations in Human saliva, the best assembly is Ti material (pure titanium-grade 4) against zirconia in terms of mechanical and electrochemical degradations. The electrochemical behavior has been investigated: the OCP, open circuit potential, is recovering its initial value even during fretting corrosion solicitations, Ti or Ti-6Al-4V against zirconia stabilized with Yttria (Y-TZP), outlier result but realistic. Some Tribological Transformed Structures on titanium material have been isolated as stir welding effect, STEM observations. Some transfer of zirconia through titanium material has been identified. Ti vs. Y-TZP clearly appears as the best performance couple under fretting corrosion conditions in human saliva. Lastly, some debris due to fretting corrosion have been isolated.