Aim The present study evaluated maximum principal stress, von Mises stress, and deformation on the mandible and surrounding structures during the insertion of an implant in various anatomical positions. Materials and Methods Finite element models of straight two-piece implants of 4.5 mm × 11.5 mm were modeled using Ansys software, v. 16.0 (Ansys, Inc., Houston, TX, USA). The mandibular model was derived through cone-beam computed tomography of a cadaveric mandible using Mimics software (Materialise NV, Leuven, Belgium). An osteotomy was performed at the first molar region, second premolar region, lateral incisor region, central incisor region, canine region, and second molar region that had varying bone densities. Implant insertion was simulated with a variable load of 1 - 180 Newton, which was applied axially downward with a rotational velocity of 30 - 120 rpm. Maximum principal stresses, von Mises stress distribution at the implant insertion site, and maximum deformation on the entire mandible were recorded during the insertion of the implants. Results Maximum principal stress was highest in the crestal area of the right first molar region and least in the middle third of the central incisor region during implant insertion. Von Mises stress in the mandible was highest in the right first molar region and the least in the lateral incisor region during implant insertion. The extent deformation was recorded on the x-axis, y-axis, and z-axis of the mandible. Deformation on the x-axis was highest at the crestal region of the canine and least for the lateral incisor. On the y-axis, deformation was highest at the symphysis region during implant insertion at the first molar region and the least at the condylar area during implant placement in the canine area. On the z-axis, the deformation was highest at the condylar region during implant insertion at the first molar region, and the least was observed in the symphysis region during implant placement in the second molar region. Conclusion When overall stress was considered, there is a direct correlation between stress and quality of bone. The highest maximum principal stress and von Mises stress were recorded during the placement of implants in posterior regions of the mandible, which suggests that the presence of dense cortical bone results in higher stress values. The maximum deformation was observed at different regions of the mandible, away from the site of implant insertion. The resultant stress and deformation exerted on the bone during placement of implants at different sites in the mandible varies, which could be detrimental factors in the longevity of the implant.
Keywords: finite element; flexible deformity; implant success; maximum principal stress; von mises.
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