Biomechanical analysis of stress distribution of dental implant with different neck thread pitch design under dynamic loading

Objective To evaluate the effects of different thread designs in implant neck area by analyzing the Von-Mises stress distribution between the implant and bones when it was in the simulating cycle of mastication by three dimensional finite element analysis. Methods Dental implants models were designed as a cylindrical shape with trapezoidal thread pitch of 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm in neck area by using computer aided design (CAD) software. Then, these implants were combined with mandible model after CT scan data's reconstruction. In immediate loading, this study loaded a dynamic force within a mastication cycle of 0.875 s on implant and the simulation analysis was done by applying the finite element software ANSYS Workbench. The Von-Mises stress changes in implants with different pitches and the surrounding alveolar bone were compared. Results In immediate loading, the amplitude of peak Von-Mises stress of implant and cortical bone were 67.15% and 74.02% respectively under vertical loading (F1) in mastication cycle on the premolar. The minimum stress (21.749 MPa) was obtained in the implant with pitch of 1.0 mm. Under oblique 45°buccal-to-lingual loading (F2), the minimum stress of the implant in the pitch of 1.0 mm was 79.175 MPa. The minimum stress of implant was 78.612 MPa when the implant tread pitch was 0.8 mm under oblique 45°buccal-to-lingual loading (F3). When the pitch changed, the stresses of the cancellous bone in 0.8 mm and 1.0 mm models were relatively lower. Conclusion For cylindrical trapezoidal threaded implants, the comprehensive mechanical properties of the implant-bone systems with 0.8 mm and 1.0 mm thread pitch in neck area are better in the case of simulating the cycle of mastication on the premolar.