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目的依据直丝弓矫治器的设计特点,建立下颌骨、牙、牙周膜、牙槽骨及直丝托槽整体三维有限元模型,分析下颌切牙整体压低移动对牙周组织的应力变化。方法在三维有限元模型上,模拟临床中下切牙整体压低移动时,牙周膜、牙槽骨、根尖应力变化。结果建立了含有25个实体模型及436 640个节点,2 699 552个单元格三维有限元模型。牙槽骨、牙周膜及牙根表面应力相比较,不管是拉应力还是压应力,牙周膜最小,牙根表面次之,牙槽骨最大。结论直丝弓矫治器压低下前牙时,牙齿的压低移动是冠唇向倾斜移动但接近整体移动。选择0.5N的力压低下颌切牙时接近整体移动。下切牙压低移动时,牙根尖尤其是根尖的唇舌侧及牙根上1/3的唇舌侧是引起牙根吸收的危险部位。
Objective To establish a three-dimensional finite element model of mandibular, odontogenic, periodontal ligament, alveolar bone and straight wire brackets based on the design features of straight wire appliance, and to analyze the changes of stress on the periodontal tissues under the condition of mandibular incisors moving downward. Methods The stress on the periodontal ligament, alveolar bone and root apical changes were simulated on the three-dimensional finite element model. Results A three-dimensional finite element model with 25 physical models and 436 640 nodes and 2 699 552 cells was established. Alveolar bone, periodontal ligament and tooth root surface stress, whether tensile or compressive stress, the smallest periodontal ligament, followed by the root surface, the largest alveolar bone. Conclusions When the straight wire appliance depresses the anterior teeth, the pressure of the teeth moves downward while the upper lip moves obliquely, but moves closer to the whole. Select 0.5N force lower jaw incisors close to the overall movement. Lower incisors move down, the root tip, especially the apex of the lingual side and the root of the upper 1/3 of the lingual side is the root cause of dangerous parts of the root absorption.