Objective To establish the implant-mandible model with different design parameters, observe stress distributions on the implant and surrounding bone, and analyze the influence of different design parameters on dental implant of the mandible. Methods Eight implant models were designed based on structural characteristic parameters (implant diameter, thread depth, height of abutment through gingiva, thread shape), and assembly of the mandibular model was performed respectively. The models were applied with static 150 N vertical and oblique 45° loads, so as to analyze peak von Mises stress of the implant and bone tissues and explore the structural parameter variables of implant most sensitive to peak von Mises stress. Results The peak stress of the mandible was larger under inclined load than that under vertical load. Implant diameter was the key factor affecting the peak von Mises stress of cortical bone, while thread depth was the key factor affecting the peak von Mises stress of cancellous bone. The peak von Mises stress was also affected by the height of abutment through gingiva, but the effect was not as significant as thread depth and implant diameter. Thread shape had little effect on the peak von Mises stress of the mandible. Conclusions Different implant design parameters can affect the peak stress of different tissues of the mandible, so it is necessary to carefully consider the selection of implant parameters for personalized implants. This study can provide theoretical guidance for structural parameter design of oral implants and provide references for accurate prediction of oral implants.

Objective To analyze stress distributions on mandible bone and periodontal ligaments during acceleration of orthodontic tooth movement by mechanical vibration, and investigate the mechanism of static-vibration coupled loading to accelerate orthodontic tooth movement. MethodsThe finite element model including tooth, periodontal ligament, cancellous bone and cortical bone was established by Mimics，SolidWorks，Geomagic and ANSYS Workbench software. Conventional static orthodontic force and low-magnitude high-frequency mechanical vibration loads were applied to the finite element model for dynamic analysis. ResultsThe compression and tension zones of alveolar bone and periodontal tissues were identified based on Y-normal stress distribution of alveolar bone and periodontal tissues, which was periodic with the same frequency as the applied low-magnitude high-frequency vibration. The von Mises stress of alveolar bone and periodontal tissues also showed periodic changes, but the compression and tension zones of alveolar bone and periodontal tissues could not be identified based on von Mises stress distribution of alveolar bone and periodontal tissues. Conclusions In the field of orthodontics, Y-normal stress is a reasonable mechanical stimulus, and static-vibration coupled loading is an effective method for accelerating orthodontic treatment. The research findings can provide guidance for low-magnitude high-frequency mechanical vibration to accelerate orthodontic tooth movement.