Evaluation of different fixation methods with finite element analysis in total mandibular subapical osteotomy

The purpose of the study was to evaluate the stress distribution in various miniplates that were used in cases that underwent advancement with total mandibular subapical osteotomy (TMSO) using finite element analysis (FEA).

Cone beam computed tomography (CBCT) images of a patient with appropriate bone tissues were used as a reference for the modeling of the mandible. In all mandibular models, horizontal TMSO was performed in a region 5 mm away from the apex of the teeth and vertical TMSO was performed in the retromolar region, 10 mm posterior to the second molar tooth. After TMSO, the dentoalveolar segment was advanced 3 mm and miniplates were placed symmetrically at four points for fixation. Four different miniplates with 2.0 mm thickness were used. Three different forces were applied to the models. Stress distribution on the models was evaluated using maximum von Mises stress values.

The maximum von Mises stress occurred in Y + I and Y + L models following the application of 300 N force from the incisal. An evaluation of posterior unilateral force indicated that the stress was remarkably high in the models with a posterior I-plate. The stress in the Y + I model was higher under unilateral force compared to the stress in other models. Under posterior bilateral force, the maximum von Mises stress values ​​occurred in the I-plates of T + I, Y + I, and L + I models (1006, 1012, and 1004 MPa, respectively).

Within the limitations of our study, we found that the ideal stress distribution was in the T + L and L + L plate combinations in the plates used for fixation after advancement with TMSO.