Oral and Maxillofacial Surgery, Faculty of Dentistry, Ain Shams University.
Mechanical Department, Faculty of Engineering, Helwan University.
J Craniofac Surg. 2021 Sep 1;32(6):1977-1980. doi: 10.1097/SCS.0000000000007320.
Assessment of stress and micromotions using finite element analysis along both the intraoral and the extraoral distractors devices used in the mandibular distraction of post temporomandibular joint ankylosis deformed mandible patients. The process of finite element analysis was carried out to assess distraction models. The first model was an extraoral mandibular distraction model and the second model was an intraoral mandibular distraction model. To analyze the stress state, 2 vertical loads were applied on the defective and normal side respectively by a 3D finite element ball model. The intraoral system observed lower stress (4.5 MPa) in the mandibular bone compared to the extra-oral system (11.5 MPa). The results revealed that the intraoral system observed higher stress on the distractor fixing points (392.21 MPa) compared to the extra-oral fixing points (12.62 MPa). The results revealed that the extra-oral system reflected higher displacement on the bone surrounding the screws of about 3720 μm compared to the intraoral system 1414.6 μm. Internal devices give better shielding to the bone and induce fewer stresses over the mandibular, so it is more advisable to be used. The external devices permit greater distraction length because the pins and the distractor main body are subjected to fewer stresses.
使用有限元分析评估颞下颌关节强直畸形下颌骨患者使用的口内和口外牵引器在沿内、外两种牵引器装置时的应力和微运动。进行有限元分析过程以评估牵引模型。第一个模型是口外下颌骨牵引模型，第二个模型是口内下颌骨牵引模型。为了分析应力状态，通过三维有限元球模型在缺陷侧和正常侧分别施加了 2 个垂直载荷。与口外系统（11.5 MPa）相比，口内系统观察到下颌骨的应力较低（4.5 MPa）。结果表明，与口外固定点（12.62 MPa）相比，口内固定点观察到的固定器更高（392.21 MPa）。结果表明，口外系统反映出螺钉周围骨骼的位移较高，约为 3720 μm，而口内系统为 1414.6 μm。内固定装置可更好地保护骨骼并在颌骨上产生较少的应力，因此更可取。外部设备允许更大的牵引长度，因为销钉和牵引器主体承受的应力较小。
