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Abstract Background Zygomatic implants are becoming an ideal treatment approach for implant-supported prosthesis treatment developed for the atrophic maxilla. This study aims to evaluate the amount and distribution of stress in implants and peri-implant bone using different implant-supported prosthesis configurations in Aramany Class I maxillary defects through 3-dimensional finite element analysis. Methods A 3-dimensional finite element model of the Aramany class I defect was created. Three different implant-supported prostheses were modelled: model 1: 1 zygomatic implant and 3 dental implants, model 2: 1 zygomatic implant and 2 dental implants, and model 3: 2 zygomatic implants. Vertical and horizontal loads of 150 N were applied in 6 different ways to the defected and non-defective areas. Maximum principal stress and von mises stresses in the bone surrounding the implants were evaluated. Results When all loading conditions were evaluated with both porcelain layer on Co-Cr framework and acrylic layer on acrylic framework, the highest maximum principal stress value was observed in Model 3. In contrast, the lowest value was observed in Model 1. The highest maximum principal stress occurred when a horizontal load was applied simultaneously to both the defective and non-defective areas. In contrast, the lowest value was observed when a vertical load was applied to the non-defective area. The von Mises stress values were found to be similar across all models when both restoration materials were used. Conclusions Based on the results of this study, it can be concluded that increasing the number of implants in the non-defective area reduces the highest stress value while using acrylic as a restoration material slightly increases the stress value.

Purpose: The purpose of this study is the biomechanical investigation of the rotation, stress and deformation caused in the talus, under a specific load, by various fixation methods in ankle which has supination external rotation (SER) injury and deltoid rupture. Method: Ankle of a healthy individual was analyzed with the help of a package program which was based on finite elements method (FEM). Then, SER injury model was created. Lateral malleolar plate was fixed with a screw and created different repair models for ankle fit. In the analysis section, forces obtained from the literature were applied to the healthy and repaired models. As the result of the analyses, mechanical values which occured in the talus were obtained. Results: As a result of this study, mechanical changes in talus, which were caused by, (in order) deltoid ligament repair, suture button syndesmosis fixation, syndesmosis fixation with transfixation screw, suture button fixation + deltoid ligament repair and transfixation screw + deltoid ligament repair in the SER type 4 injury model with deltoid ligament rupture, were evaluated. Conlusion: This study showed that the application of syndesmosis screw together with deltoid ligament repair in the treatment of SER type 4 ankle injuries with rupture of deltoid ligament made regression, displacement and talus rotations on the talus almost normal. In addition, syndesmosis fixation screw applications give better results than syndesmosis fixation suture button applications.

Abstract In this paper, continuous and discontinuous cases of a contact problem for two elastic layers supported by a Winkler foundation are analyzed using both analytical method and finite element method. In the analyses, it is assumed that all surfaces are frictionless, and only compressive normal tractions can be transmitted through the contact areas. Moreover, body forces are taken into consideration only for layers. Firstly, the problem is solved analytically using theory of elasticity and integral transform techniques. Then, the finite element analysis of the problem is carried out using ANSYS software program. Initial separation distances between layers for continuous contact case and the size of the separation areas for discontinuous contact case are obtained for various dimensionless quantities using both solutions. In addition, the normalized contact pressure distributions are calculated for both cases. The analytical results are verified by comparison with finite element results. Finally, conclusions are presented.