Biomechanical evaluation of early effects of different fixation configurations applied with or without grafting material after various amounts of superior repositioning of the osteotomized segment in mandibular anterior segmental osteotomies

The aim of this study was to evaluate the mechanical behavior of different fixation methods and the graft material used for the reconstruction of the osteotomy gap under vertical, horizontal and oblique anterior occlusal loads following mandibular anterior segmental osteotomies. In this study 3 and 5 mm of superior repositioning of mandibular anterior segmental osteotomies were simulated on the 3D finite element models obtained from CBCT data of cadaver mandible. Two distinct models which were either grafted of non-grafted were created for all superior repositioning models. The osteotomy gap was reconstructed with demineralized freze-dried block bone allograft. Three different fixation configurations consisting of two right and left L plates and I plates were created for grafted and non-grafted models. Anterior occlusal forces reflecting chewing forces in three directions were simulated on the osteotomized segment. Von Mises and principal stress values were calculated for simulations of different amounts of superior repositioning of the osteotomized segment. It was concluded that the right L plate configuration provided the most stable fixation compared with other fixation methods used in this study. The highest Von Mises stress values on the plates, screws and principal stress values on the bones were found in non-grafted models compared with grafted models. Von Mises and principle stress values were found to be higher in 5 mm superior repositioning models when compared with 3 mm superior repositioning models. The graft material had a significant contribution for reducing stress values on fixations and bone.