不同牵引部位对上颌埋伏中切牙牙周应力分布的影响

目的:基于对上颌唇向倒置埋伏中切牙的三维有限元模型施加不同部位的牵引力,分析比较不同工况下牙周膜的应力分布,从而为临床进行上颌埋伏中切牙助萌治疗提供参考。方法:选取1名上颌中切牙唇向倒置埋伏阻生患者的锥体束CT(CBCT)原始数据,建立统一坐标系下上颌埋伏中切牙及其支持组织的三维有限元模型。在牙冠舌面切1/3、中1/3、颈1/3的中心分别施加在矢状方向上垂直于牙体长轴的30 g、60 g、90 g的牵引力,分析比较不同工况下牙周膜的应力分布情况。结果:不同牵引部位下,埋伏牙牙周应力分布特点类似。同一力值牵引,牵引部位越靠近牙颈部,牙周膜的应力越小;同一牵引部位,牵引力越大,牙周应力越大。结论:牵引部位应尽量位于切端,牵引力不宜超过60 g。

Effects of Traction Position on the Periodontal Stress Distribution of Impacted Maxillary Central Incisor.

Objective: To analyze the stress of periodontal tissues in different conditions by establishing the three dimensional finite element model of an impacted labial inverted maxillary central incisor and its supporting tissues,and to provide some reference for the treatment of impacted maxillary central incisor. Methods: Three-dimensional finite element model of impacted labial inverted maxillary central incisor and its periodontal tissues were established based on original data of cone beam computed tomography (CBCT). Various tractions (30g, 60g, 90g) were exerted on the incisal, middle and cervical of the lingual surface in the direction perpendicular to the impacted incisor, respectively. And then, different Von Mises stress was determined and analyzed. Results: The characteristics of stress distribution were similar in different traction position. The closer the traction to the cervix was, the smaller stress distribution in periodontal ligament was. The bigger the traction power was, the larger stress distribution in periodontal ligament was. Conclusion:The traction position had better be exerted on the incisal margin and the optimal traction power should not exceed 60g.