Zirconia abutments and reduced crown-to-implant ratios: Insights into stress distribution

This study aims to evaluate stress distributions in dental implants, zirconia abutments, and peri-implant bone tissues at different crown-to-implant ratios. In-silico analysis was performed using SolidWorks (SolidWorks Corporation, Concord) to evaluate stress distributions in the implant and abutment based on von Mises stresses, as well as in cortical and trabecular bone under maximum and minimum principal stresses. Implant-supported rehabilitation (4 × 11 mm) was simulated with zirconia abutments measuring 8 mm (RS), 10 mm (SS) and 12 mm (LS), corresponding to crown-to-implant ratios of 0.72:1, 0.90:1 and 1.1:1, respectively. An axial load of 200 N was applied and stress distribution was analyzed using numerical data and color-coded images. The RS group exhibited the highest von Mises stress (188.63 MPa), localized above the first implant thread, while SS and LS showed ~178 MPa. Additionally, RS abutments exhibited higher von Mises stress values in the implant (336.23 MPa, SS and LS: ~325 MPa), concentrated in a smaller area close to the first threads of the implant. Regarding stress in bone tissue, lower values of maximum (1.99 MPa, SS and LS: ~2.4 MPa) and minimum (-8.69 MPa, SS and LS: ~-10.6 MPa) principal stresses were found in the RS group compared to the SS and LS groups, suggesting better performance. No differences in stress distribution values were observed between the SS and LS groups. These findings suggest that a lower crown-to-implant ratio provides the most favorable stress distribution and that abutment cervical-occlusal length influences the effectiveness of oral rehabilitation.