Abstract

The purpose of this study was to investigate how sagittal split ramus osteotomy (SSRO) and Le Fort 1 osteotomy affected the stress distribution of the temporomandibular joint (TMJ) during an anterior teeth bite using the three-dimensional (3D) finite element method. 14 orthognathic surgery patients were examined with mandibular prognathism, facial asymmetry and mandibular retraction. They underwent Le Fort 1 osteotomy in conjunction with SSRO. In addition, 10 asymptomatic subjects were recruited as the control group. The 3D models of the mandible, disc and maxilla were reconstructed according to cone-beam computed tomography (CBCT). Contact was used to simulate the interaction of the disc-condyle, disc-temporal bone, and upper-lower dentition. Muscle forces and boundary conditions corresponding to the anterior occlusions were applied on the models. The stresses on the articular disc and condyle in the preoperative group were significantly higher than normal. The contact stress and minimum principal stress in TMJ for patients with temporomandibular disorder (TMD) were abnormally higher. The peak stresses of the TMJ of the patients under anterior occlusions decreased after bi-maxillary osteotomy. No postoperative TMD symptoms were found. Maxillofacial deformity led to excessive stress on the TMJ. Bi-maxillary osteotomy can partially improve the stress distributions of the TMJ and relieve the symptoms of TMD.

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