皮质骨切开辅助大鼠正畸牙齿移动有限元分析

目的 仿真模拟大鼠皮质骨切开后正畸牙齿移动，分析切开手术对大鼠牙颌结构力学分布的影响。方法 建立大鼠正畸牙齿移动三维有限元模型，模拟皮质骨切开手术，并根据加载方向及牙根部位对牙周膜及根周牙槽骨进行细分，计算磨牙与切开骨块初始位移及各细分区域内牙周膜、牙槽骨的应力、应变分布。结果 上颌第1磨牙在正畸力作用下近中倾斜移动，最大位移集中于牙冠远中尖；皮质骨切开能增加牙槽骨块初始位移。牙周膜最大主应变集中于近远中颈部，最小主应变集中于远中根尖部；皮质骨切开对牙周膜应变的分布及水平有明显影响；皮质骨切开能够明显增加牙槽骨中应力水平，并使高应力区集中于牙根近中牙槽嵴。结论 皮质骨切开能够改变正畸矫治力在牙齿及牙周组织中的分布，使其有利于局部牙槽骨改建，实现快速正畸牙齿移动。研究结果有助于从生物力学角度认识皮质骨切开辅助正畸牙齿移动机制。
Objective To simulate the orthodontic tooth movement (OTM) after corticotomy in rat and analyze its effects on mechanical distribution in dentoalveolar structures.Methods 3D finite element model of corticotomy-facilitated OTM in rat was established and the circumscribing corticotomy approach was simulated. The periodontal ligament (PDL) and alveolar bone around the mesial root were partitioned according to direction of the orthodontic load and corresponding part of the root. The initial displacement of the first molar and segmented alveolar bone as well as the stress and strain in PDL and alveolar bone were calculated. Results The first molar presented a tipping movement and the distal cusp showed the maximum displacement. Corticotomy could increase the relative displacement of bone segment. The maximum principal strain in PDL concentrated on the mesial and distal cervical region, while the minimum principal strain concentrated on the distal apical region. Corticotomy could change the distribution and magnitude of the maximum and minimum principal strain in PDL and Von Mises stress in alveolar bone. Conclusions Corticotomy can affect the mechanical distribution of orthodontic force in tooth and periodontal tissues around, and hence facilitate regional bone remodeling to realize rapid OTM. The research findings contribute to understanding the mechanism of corticotomy to facilitate OTM from the aspect of biomechanics.