25 / 2021-06-27 16:30:30

Effect of plasma nitriding on fatigue performance of Ti6Al4V abutment screw

Dental implant, Plasma nitriding, Fatigue life, Screw loosening, FEA

Mechanical properties play an important role in the long-term service of dental implants. The most common issues are fatigue fracture and self-loosening of abutment screws. In this paper, the fatigue performance of plasma nitriding (PN) for implant system applications was investigated. The abutment screws were first prepared by PN. The preload and friction coefficient of the abutment screws, as well as the settlement and pull-out force of the implant-abutment interface, were measured. Then, the static fracture test and dynamic fatigue life test of the implant system were done to investigate the fatigue properties of the implant system. The fracture location is verified by the finite element analysis (FEA). Finally, the loosening torque of the screw under static and dynamic loads was measured, and the surface fracture morphology of the implant system and surface wear morphology of the screw were observed. The results indicated the PN treatment reduced the friction coefficient, increased the preload, settlement value, pull-out force, and static fracture load, and prolonged fatigue life. Abutment screws with PN treatment showed a different fatigue fracture mode. Most of the fatigue fracture occurred at the neck region of the implants and the first thread of the abutment screws, consistent with the FEA results. In addition, the PN treatment improved the anti-loosening performance under dynamic load. PN can reduce the wear of screw surfaces and protect the integrity of the thread. Therefore, PN treatment results in greater mechanical performance and may be a suitable way to optimize the fatigue performance of dental implants.