https://app.oxfordabstracts.com/events/123/program-app/submission/20180 — Program: 8th World Congress of Biomechanics Programme (app.oxfordabstracts.com)
P4104
The effects of bilateral sagittal split ramus osteotomy on the stress distribution in temporomandibular joint under the unilateral occlusions
Dr Yuanli Zhang1,2, Dr Zhan Liu2
1Department of Medical Technology, Chongqing Three Gorges Medical College, Chongqing, China. 2Provincial Key Lab for Biomechanical Engineering, Sichuan University, Chengdu, China
ABSTRACT
Introduction
Facial asymmetry is one of the most common types of jaw deformities. The prevalence of facial asymmetry varied from 8.7% to 23.3% [1]. The signs and symptoms of temporomandibular joint (TMJ) dysfunction are commonly found in patients with facial asymmetry. Bilateral sagittal split ramus osteotomy (BSSRO) is a representative surgery for the correction of facial asymmetry. The morphology of TMJs in patients with facial asymmetry was proven to be improved after the BSSRO [2]. However, the biomechanical effects of BSSRO on TMJs are unclear. The purpose of this study was to compare the differences in the stress distributions in the TMJs between the asymptomatic subjects and facial asymmetry patients, pre-operatively and post-operatively.
Methods
Ten patients (Pre-operation and Post-operation groups, 24.6±4.8 years) diagnosed with facial asymmetry and ten asymptomatic subjects (Control group, 26.8±4.9 years) took part in this study. Three-dimensional (3D) finite element models of the mandible, disc, maxilla and teeth were reconstructed with 3D image software. Contact elements were used to simulate the interaction of the disc-condyle, disc-temporal bone and upper-lower dentition. The same muscle forces and boundary conditions corresponding to the unilateral occlusions were applied on the models of the Pre-operation, Post-operation and Control groups. The stresses in each group were assessed by Student t-test and the level of significance was 0.05.
Results
The stresses of TMJ in the Pre-operation group were significantly higher than those in the Control group, especially on the non-occlusal side of TMJ. At six months after BSSRO, the contact stress, maximum and minimum principal stress and von Mises stress in Post-operation group were significantly smaller than those in the Pre-operation group. Meanwhile, there was no significant difference for the stresses of TMJ between the Post-operation and Control groups (Figure 1). The results suggested that BSSRO could significantly reduce the stresses of TMJ, and it may alleviate or eliminate the symptom of joint pain, joint sounds and bone resorption.
Figure 1. The von Mises stress (MPa) of TMJ in the asymptomatic subjects and facial asymmetry patients under the non-deviated side occlusion. A, anterior; P, posterior; M, medial; L, lateral; T, top; B, bottom.
Discussion
The BSSRO could decrease the excessive stresses of TMJ in the preoperative patients. The stress distributions of TMJ in postoperative patients were consistent with those in the asymptomatic subjects. Therefore, BSSRO could significantly improve the biomechanical environment of TMJ for patients with facial asymmetry, and it may alleviate or eliminate the TMD symptoms to some extent.
Acknowledgements
This study was supported by the National Natural Science Foundation of China under Grant Number 31670963 and 11202143.
References
- 1. Bishara et al., (1994). Angle Orthod 64(2):89-98.
- 2. Ueki et al., (2012). J Craniomaxillofac Surg 40(8):821-827.
이 글은 네이버 블로그에서 가져온 글입니다. 원문: blog.naver.com/surgeon
답글 남기기