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目的:采用三维有限元法建立上颌前牙模型,并研究其阻抗中心的垂直向定位。方法:在ANSYS8.1软件中建立6个上前牙及前颌骨的三维有限元模型,以2mm×2mm的不锈钢唇弓紧密固定6个上前牙,对其双侧施加150g水平向后牵引力,施力的高度分别为2～14mm,经求解得出模型内各节点的三维位移和应力分布趋势。结果:上前牙的位移和应力分布趋势随着水平向后牵引力的高度增加而变化。切牙的唇舌向位移由冠舌向倾斜逐渐变为舌向整体移动和舌向控根移动,尖牙则以冠舌向倾斜位移为主;前牙位移量随牵引力高度增加而增大,但位移趋势较为稳定;牙周膜应力分布与其位移趋势一致。牵引钩长度为10mm时,6个前牙的舌向位移和牙周膜的应力分布最为均匀。结论:标准大小的上颌6个前牙的阻抗中心垂直向上位于中切牙切缘龈方14mm左右。
OBJECTIVE: To establish a model of maxillary anterior teeth using three-dimensional finite element method and to study the vertical orientation of its impedance center. Methods: Six finite element models of anterior teeth and maxillary anterior teeth were established in ANSYS8.1 software. Six anterior teeth were tightly fixed with a 2mm × 2mm stainless steel lip and 150g lateral traction was applied to both sides , The height of the force is 2 ~ 14mm respectively, and the three-dimensional displacement and stress distribution trend of each node in the model are solved. RESULTS: The displacement and stress distribution of the anterior teeth tended to change with the height of the lateral backward traction. The incisor’s tongue-and-tongue displacement was gradually changed from the crown tongue to tilt to the tongue to the whole movement and the tongue to the root control movement. The fangs were mainly diagonal displacement of the crown tongue. The anterior teeth displacement increased with the increase of the traction force, Displacement trend is more stable; periodontal ligament stress distribution consistent with its displacement. When the length of traction hook is 10mm, the lingual displacement of 6 anterior teeth and the stress distribution of periodontal ligament are the most uniform. CONCLUSIONS: The impedance centers of the six maxillary anterior maxillas of standard size are vertically upwards of 14 mm at the gingival margin of the incisors.