Evaluation of the efficacy of mandibular molar distalization with miniplate and buccal shelf miniscrews by 3-dimensional finite element stress analysis

Evaluation of the Efficacy of Mandibular Molar Distalization with Miniplate and Buccal Shelf Miniscrews by 3-Dimensional Finite Element Stress Analysis. Aim: The aim of this study was to investigate the force and stress distributions of mandibular molar distalization methods with miniplate and buccal shelf miniscrews in jawbone by using finite element analysis method separately and to compare the obtained data and to predict the differences during treatment. Material and Method: In our study, two different models were applied by using finite element analysis. In the first model, a 2×12mm stainless steel buccal shelf miniscrew was placed in the mandibular buccal shelf region. In the second model, the L shaped miniplates were placed in the retromolar fossa between the anterior border of the mandibular ramus and the temporal crest. From the buccal shelf miniscrew and miniplate head, which corresponds to the contact point of the mandibular first and second molars, at a 30° angle, 300 g of force was applied to the hooks positioned between the canine and first premolar, on a 0.019×0.025 inch stainless steel archwire with nickel-titanium close-coil springs. Von Mises stress, maximum and minimum principal stresses, displacement values were obtained from the models and evaluated comparatively. Results: The buccal shelf miniscrews were displaced in the force direction and the highest stress was observed in the neck region. In the miniplate, Von Mises stress was mostly observed in the arm parts, while in fixation screws was seen in the neck of the inferior miniscrew. In the first model, the crowns of molar teeth were displaced distally and intrusion was observed. In addition, intrusion was observed in the central, lateral and canine teeth, while extrusion was observed in the first and second premolar teeth. In the second model, the crowns of molar teeth were displaced more distally and intrusion was observed. In addition, intrusion was observed in the central, lateral and canine teeth, while more extrusion were observed in the first and second premolar teeth. Rotation of the canines in the distolingual direction occurred in both models. Conclusion: With the help of finite element analysis, the stresses and displacements caused by the forces applied using two different skeletal anchorage systems were determined at the initial time. Keywords: Mandibular molar distalization, buccal shelf miniscrew, miniplate, finite element analysis, orthodontics