STATEMENT OF PROBLEM: Fatigue failure of implant components is a common clinical problem. Plasma nitriding, an in situ surface-strengthening method, may improve fatigue properties of dental implants. PURPOSE: The purpose of this in vitro study was to evaluate the effect of plasma nitriding on the fatigue behavior of implant systems. MATERIAL AND METHODS: The preload and friction coefficient of plasma nitrided abutment screws, as well as settlement of the implant-abutment interface, were measured. Then, the reverse torque values and pullout force were evaluated after cyclic loading. Finally, the fatigue properties of the implant system were investigated with static fracture and dynamic fatigue life tests, and the morphology of the fracture on the surface of the implant system was observed. RESULTS: The plasma nitriding treatment reduced the friction coefficient; increased the preload, settlement value, reverse torque values, pullout force, and static fracture load; and prolonged fatigue life. Furthermore, abutment screws with plasma nitriding treatment showed a different fatigue fracture mode. CONCLUSIONS: Plasma nitriding improved mechanical performance and may be a suitable way to optimize the fatigue behavior of dental implants.
