2018 年 27 巻 1 号 p. 11-16
This study aimed to evaluate the mechanical stress on resected mandibular bone against occlusal force using dental implant without any bone grafting by finite element analysis to reduce the risk of the bone fracture. A model of marginal resection of the symphysis of the mandible, in which the bone height of the region was 5, 10 or 15 mm, was prepared. Two, four, or six implant-supported fixed prostheses (superstructure) or overdenture were set up in the model and loaded with 500N of occlusal force. The von Mises stress on the resected region was the highest when two implants were bilaterally placed at positions closest to the resected region. The von Mises stress value on the resected region could be high enough to induce the bone fracture. The mechanical stress was reduced up to < 50 % by adding implant at posterior position and connecting all implants. The presence of superstructure on 4 or 6 implants significantly decreased the von Mises stress when the residual bone height was 10 or 15 mm. Use of 6 implants showed no significant advantage at the stress reduction compared to use of 4 implants. When the residual bone height was 5 mm, reinforcement of the residual bone or bone graft should be considered to avoid the bone fracture. Although the present results were obtained under restrictive conditions, the number of implant, implant position, and prostheses style could reduce the von Mises stress and the risk of bone fracture on the resected region.