上颌第一磨牙正畸移动对颧突支柱改建的影响研究

Effect of Orthodontic Movement of Maxillary First Molar on Zygomatic Pillar Remodeling

目的:研究上颌第一磨牙正畸移动对颧突支柱整体结构的影响以及颧突支柱结构改建与后牙咬合变化的相关性。方法:选取50例错颌畸形患者(对照组)以及50例减数正畸治疗成人患者(实验组),用Teetester咬合分析系统分析两组人群的咬合接触特征。从实验组中选取25例具有完整锥束计算机断层扫描(cone-beam computed tomography,CBCT)影像的患者,用Mimics21.0软件分析测量CBCT影像,界定三维方向测量基准平面,划分颧突支柱解剖区域区。测量支柱横截面积,表面标志点位移及上颌第一磨牙移动量、牙根周围牙槽骨、颧突支柱皮质骨厚度和密度。结果:正畸治疗后上颌第一磨牙在矢状向、垂直向、颊腭向位置均有变化,以近中向移动量最大。正畸矫治后颧突支柱下段横截面积变小,牙槽骨颊舌向厚度以及皮质骨厚度减小,颧突点及颧颌缝最下点向后位移,上述变化与上颌第一磨牙移动有相关性。而上颌第一磨牙牙根部分区域牙槽骨松质骨密度降低,皮质骨密度变化不明显,这些变化与牙齿移动无相关性。与对照组相比,正畸刚结束时实验组总咬合接触面积、总咬合力以及上颌第一磨牙[牙合]力均降低。前牙咬合力占比升高。结论:减数正畸矫治前后,伴随上颌第一磨牙三维方向的位置变化,颧突支柱中、下段形态结构随之改建,二者具有相关性,且这些改建影响了咬合力的大小以及咬合力的分布。因此上颌磨牙正畸移动过程引起颧突支柱部分结构改建,这些改建可能进一步影响咬合接触。

Objective:To study the effect of orthodontic movement of maxillary first molar on the structure of zygomatic pillar and the correlation between structural alteration and occlusal changes.Methods:Fifty patients with malocclusion(control group)and 50 patients receiving orthodontic treatment with extraction(experimental group)were selected,and the occlusal contact characteristics of two groups were analyzed with the Teetester,.Twenty-five patients with complete CBCT images were selected from the experimental group,and the CBCT images were analyzed with Mimics 21.0.The cross-sectional area of the zygomatic pillar,the movement of surface markers and the maxillary first molar,and the thickness and density of the alveolar bone and the cortical bone of the zygomatic pillar were measured.Results:The maxillary first molar showed changes in three-dimensional directions after orthodontic treatment,with significant mesial movement.The cross-sectional area of the lower section of the zygomatic pillar became smaller,the zygomatic point and the lowest point of the zygomaticomaxillary suture were displaced posteriorly,the thickness of the alveolar bone and the cortical bone decreased,and the above changes were correlated with the movement of the maxillary first molar.Total occlusal contact area(TCA),total occlusal force(TOF),and occlusal force of the maxillary first molar were reduced in the experimental group.Conclusion:Before and after orthodontic treatment with extraction,there was a correlation between the movement of maxillary first molar in three-dimensional directions and the modification of the structure of zygomatic pillar in the middle and lower segments.These alterations may affect the magnitude and the distribution of occlusal force.