The increasing prevalence of peri-implantitis has led to a growing clinical use of implantoplasty, a procedure involving intraoral machining of the dental implant sur-face to remove biofilm. The absence of standardized clinical protocols may contribute to premature fatigue failure of dental implants. The present study aimed to determine the influence of machining depth on the cyclic mechanical behavior of dental im-plants. A total of 250 commercially pure Grade 3 titanium dental implants were dis-tributed into four groups according to machining depth: untreated (original), 0.2 mm, 0.4 mm, and 0.6 mm wall reduction. The implant system featured an internal connec-tion with a thread height of 0.4 mm. Finite element analysis was performed for each machining depth to evaluate Von Mises stress distribution and to simulate fatigue be-havior. The numerical models were validated through experimental fatigue testing using a servohydraulic MTS Bionix testing machine under ISO 14801:2016 standard conditions. Fractographic analysis was conducted by scanning electron microscopy. The results revealed that maximum Von Mises stresses were concentrated at the junc-tion between the implant thread and the implant body. The fatigue limit of the un-treated implants was approximately 400 N. Implants subjected to 0.4 mm machining exhibited a fatigue limit of 350 N, whereas lower fatigue limits were observed for 0.2 mm (290 N) and 0.6 mm (180 N) reductions. These findings demonstrate the signifi-cant mechanical effect of thread removal. At higher applied loads, fracture occurred in the coronal region of the implant, whereas at lower loads failure shifted to the im-plant–abutment connection. Finite element predictions showed high agreement with experimental results. The findings highlight a clinically relevant criterion: implanto-plasty depth should not exceed the original thread height, as excessive wall reduction markedly compromises fatigue resistance and long-term mechanical reliability.

The increasing prevalence of peri-implantitis has led to a growing clinical use of implantoplasty, a procedure involving intraoral machining of the dental implant surface to remove biofilm. The absence of standardized clinical protocols may contribute to premature fatigue failure of dental implants. The present study aimed to evaluate the influence of machining depth on the cyclic mechanical behavior of dental implants. A total of 250 commercially pure grade 4 titanium dental implants were distributed into four groups according to machining depth: untreated (original), 0.2 mm, 0.4 mm, and 0.6 mm wall reduction. The implant system featured an internal connection with a thread height of 0.4 mm. Finite element analysis was performed for each machining depth to evaluate von Mises stress distribution and simulate fatigue behavior. The numerical models were validated through experimental fatigue testing using a servo-hydraulic MTS Bionix testing machine under ISO 14801:2016 conditions, showing a high correlation between simulated and experimental results (correlation coefficients > 0.9). The results indicated that maximum von Mises stresses were concentrated at the junction between the implant thread and the implant body. The fatigue limit of the untreated implants was approximately 351 N. Implants subjected to 0.4 mm machining exhibited a fatigue limit of 301 N, whereas lower fatigue limits were observed for 0.2 mm (255 N) and 0.6 mm (185 N) reductions. These findings suggest a significant mechanical effect of thread removal: 0.4 mm implantoplasty may provide improved fatigue performance compared to 0.2 mm, potentially due to reduced stress concentration at the thread–body junction. At high applied loads, fracture occurred in the coronal region of the implant, whereas at lower loads failure shifted to the implant–abutment connection. Although a good agreement between numerical and experimental results was observed, these findings should be interpreted with caution due to the in vitro testing conditions and the assumptions inherent to the finite element simulations. Therefore, while the results suggest that implantoplasty depth should not exceed the original thread height, further validation under clinically relevant conditions is required to confirm its impact on long-term mechanical reliability.