Evaluation of five fixation methods for mandibular sagittal split osteotomy in a significant advancement with counterclockwise rotation: a finite element study.

Abstract

<h4>Background</h4>This study aimed to evaluate the biomechanical behavior of five different fixation methods used in bilateral sagittal split osteotomy (BSSO), focusing on their performance with miniplates and monocortical screws during 10-mm advancement and 20º counterclockwise rotation of the occlusal plane.<h4>Material and methods</h4>A three-dimensional model of a human mandible, derived from computerized tomography scans and including all teeth except the third molars, was utilized. The BSSO procedure was simulated using SolidWorks 2017 CAD software (Dassault Systemes, SolidWorks Corp, USA) according to the techniques outlined by Epker. Five fixation models were tested: Model M1, one straight 4-hole miniplate with four monocortical screws; Model M2, two straight 4-hole miniplates with eight monocortical screws; Model M3, one 10-hole double miniplate with two bridges and ten monocortical screws; Model M4, one 8-hole 20º angled double miniplate with two bridges and eight monocortical screws; and Model M5, one semi-curved 6-hole miniplate with six monocortical screws. Each model was subjected to two loading patterns: 100 N posteriorly and 50 N anteriorly. The biomechanical performance was analyzed qualitatively and quantitatively, focusing on the bone, screws, and plates.<h4>Results</h4>Models M1 and M3 exhibited the poorest biomechanical stability; Model M2 demonstrated the highest stability; and Model M5 showed the best load distribution.<h4>Conclusions</h4>A model using two straight 4-hole plates offers more stable osteosynthesis, whereas a semi-curved plate with six nonlinear screws ensures effective load distribution with reduced stress concentration.