Sichuan University, West China Hospital of Stomatology, Department of Orthodontics, State Key Laboratory of Oral Disease, ChengduSichuan, P.R. China, State Key Laboratory of Oral Disease, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, P.R. China.
Tongji University School of Medicine, Shanghai Tenth People's Hospital, Department of Stomatology, Shanghai, P.R. China, Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, P.R. China.
J Appl Oral Sci. 2014 Jan-Feb;22(1):52-60. doi: 10.1590/1678-775720130365.
The aims of this study were to compare different surgical approaches to rapid canine retraction by designing and selecting the most effective method of reducing resistance by a three-dimensional finite element analysis.
Three-dimensional finite element models of different approaches to rapid canine retraction by reducing resistance and distraction were established, including maxillary teeth, periodontal ligament, and alveolar. The models were designed to dissect the periodontal ligament, root, and alveolar separately. A 1.5 N force vector was loaded bilaterally to the center of the crown between first molar and canine, to retract the canine distally. The value of total deformation was used to assess the initial displacement of the canine and molar at the beginning of force loading. Stress intensity and force distribution were analyzed and evaluated by Ansys 13.0 through comparison of equivalent (von Mises) stress and maximum shear stress.
The maximum value of total deformation with the three kinds of models occurred in the distal part of the canine crown and gradually reduced from the crown to the apex of the canine; compared with the canines in model 3 and model 1, the canine in model 2 had the maximum value of displacement, up to 1.9812 mm. The lowest equivalent (von Mises) stress and the lowest maximum shear stress were concentrated mainly on the distal side of the canine root in model 2. The distribution of equivalent (von Mises) stress and maximum shear stress on the PDL of the canine in the three models was highly concentrated on the distal edge of the canine cervix. .
Removal of the bone in the pathway of canine retraction results in low stress intensity for canine movement. Periodontal distraction aided by surgical undermining of the interseptal bone would reduce resistance and effectively accelerate the speed of canine retraction.
本研究旨在通过设计和选择最有效的减小阻力方法，通过三维有限元分析比较快速犬牙内收的不同手术入路，以达到减小阻力的目的。
建立了不同方法快速犬牙内收的三维有限元模型，包括上颌牙齿、牙周韧带和牙槽骨。这些模型设计用于分别解剖牙周韧带、牙根和牙槽骨。在第一磨牙和犬齿之间的冠中心施加 1.5 N 的力向量，以远中方向牵拉犬齿。总变形值用于评估力加载开始时犬齿和磨牙的初始位移。通过比较等效（von Mises）应力和最大剪应力，使用 Ansys 13.0 分析和评估应力强度和力分布。
三种模型中总变形的最大值出现在犬齿冠的远中部分，从冠部向犬齿根尖逐渐减小；与模型 3 和模型 1 相比，模型 2 中的犬齿位移最大值为 1.9812mm。等效（von Mises）应力和最大剪应力的最低值主要集中在模型 2 犬齿根的远侧。三种模型中犬齿牙周韧带的等效（von Mises）应力和最大剪应力分布主要集中在犬齿颈缘的远侧。
去除犬牙内收路径中的骨会导致犬牙运动的应力强度降低。通过切开骨间间隔的牙周骨牵引辅助牙周分散可以减小阻力，有效加速犬牙内收速度。
