Finite element analysis of stress distribution around dental implants in healthy and osteoporotic patients undergoing All-On-Four treatment concept

Rehabilitation of atrophic mandible with implant causes various problems due to insufficient amount of bone. In addition, additional adverse conditions are observed due to the low bone quality seen in individuals with oseoporotic bone structure. In the presence of insufficient bone, grafting methods can be applied, but there are multiple negative factors such as additional surgical operations and prolonged treatment process. To eliminate such problems, the All-on-Four treatment concept can be applied. The aim of our study is to evaluate the concept of All-on-Four treatment applied to the atrophic mandible by finite element analysis (SEM) method in both healthy and osteoporotic patients. In our study, 24 models were designed with the length of the implants 11.5 mm in all models and 3 different implant diameters (3.75, 4.3, 5 mm). Vertical and oblique loading scenarios were applied in the loading scenario of the models. In all models, the angle of anterior implants was designed to be straight and the angle of posterior implants to be inclined 30 degrees. The prosthetic structure of the implants was designed as a hybrid prosthesis in all models. Forces of 150 N were applied bilaterally to simulate the chewing force. Half of the models represented individuals with healthy bone structure, while the other half represented patients with osteoporosis, and the results were evaluated comparatively. According to the results obtained, although the stress values ​​are higher in patients with osteoporosis than in healthy individuals, the All-on-Four concept is a viable treatment method for patients with osteoporosis. Factors such as the use of wide implants, reduction of implant angles and elimination of oblique forces on the prosthetic structure can be considered to reduce stress values.