【摘要】 目的:研究上颌前磨牙的颊面形态及冠根成角关系对转矩的影响。方法:选自2006年1-12月中山大学光华口腔医院、暨南大学附属第一医院口腔科、深圳龙华人民医院口腔科收集的123颗正畸拔除的上颌前磨牙,其中第1前磨牙66颗、第2前磨牙57颗。利用锥形线束计算机断层扫描(CBCT)机将全部牙齿进行扫描,在CT工具软件下进行影像的三维重建并提取全部牙的正中矢状切面图像,利用自动计算机辅助设计(AutoCAD)软件对图像分别测量牙冠颊面4个不同高度的切线与牙冠长轴所成的角度;牙冠长轴与牙根长轴所成的角度。结果:不同高度间的角度变化上颌第2前磨牙变化较大,高度从3.0～4.5 mm,角度平均变化为9.17°。上颌第1、2前磨牙冠根角值分别为(4.84±4.06)°、(1.9,±3.55)°。结论:上颌前磨牙托槽粘结高度在牙合龈方不同的范围内变化相同距离对转矩的影响不同,越靠牙龈方对转矩的影响越大。上颌前磨牙存在一定的冠根角、且冠根角存在较大的个体差异。更多还原

【Abstract】 Objective:To determine the impact of buccal-sided morphology and collum angle of maxillary premolars on the torque.Methods:A total of 123 maxillary premolars extracted in the department of stomatology,Guanghua Stomatology College of Sun Yat-sen University,First Affiliated Hospital of Jinan University and Longhua People’ s Hospital of Shenzhen in January 2006 and December 2006,including 66 fist premolars and 57 second premolars,were collected.All premolars were scanned using cone beam computed tomography(CBCT),and three-dimensional images were reconstructed via the software designed for CT purposes.Additionally,images of median sagittal planes were selected for measurement of the angles between the four tangent lines of the buccal side at different heights and the longitudinal axis of the crown.Also determined was the longitudinal collum angle using automated computer-aided design(AutoCAD).Results;The maxillary second premolars presented greater variation of angle a among various heights,ranging from 3.0 mm to 4.5 mm. Mean angle difference was 9.17°and the mean collum angle of maxillary first and second premolars was(4.84±4.06)°and(1.9±3.55)°,respectively.Conclusion:The adhesion height of maxillary premolar bracket at various occlusogingival locations has distinct impacts on the torque in spite of an identical distance.Closer distance to the gingiva is associated with greater impact on the torque.The collum angles,present in maxillary premolars,differ greater among individuals.更多还原