Evaluation of stress distribution in critical anatomic regions following the Le Fort I osteotomy by three-dimensional finite element analysis.

In this study, we aimed to measure the stresses both on the pterygoid plates and the cranial base during the down-fracture and at the time of pterygomaxillary osteotomy by using the finite element analysis method to have an idea about the possible causes of complications. Three different surgical approaches were applied to the obtained models. In the Model 1, Le Fort I cuts without pterygomaxillary separation was applied. In the Model 2, same standard Le Fort I cuts were applied with pterygomaxillary separation. Then both models were subjected to a force of 150 N over the anterior spina nasalis to simulate down-fracture. In the third model, same standard Le Fort I cuts were applied. Following this procedure, a force of 50 N was applied with a sharp osteotome to the pterygomaxillary junction to simulate osteotomy. According to the results of this experimental study, the cranial base stress values decreased during the down-fracture in the Model 2. Moreover, it was found that the force transmitted to the base of the skull is less when the height of the pterygomaxillary osteotome is limited to 1 cm as we applied in Model 3.