摘要目的:结合锥形束CT(cone-beam computed tomography, CBCT)影像和Dolphin软件转化头颅侧位片，研究Andrews要素Ⅱ目标前界线(goal anterior limit line, GALL)的可重复性。方法:选取57例患者CBCT影像导入Dolphin软件转化头颅侧位片，根据Andrews要素Ⅱ进行定点测量，得出临床前额平面与FALL线(forehead's anterior limit line)所成的角度及上颌中切牙FA(facial-axis point)点至GALL线的距离。由3名经软件测量培训的专业正畸医生执行。操作者分别测量2次，间隔1周。采用组内相关系数(ICC)检验同一操作者测量可重复性，以及不同操作者对同一指标测量结果的一致性。结果:同一操作者测量上颌中切牙FA点与GALL线距离(a)及临床前额平面与FALL线所成的角度(b)，ICC检验结果表明每一位操作者对该测量方法的掌握度和可重复性好。不同操作者之间采用该测量方法测量a和b，ICC分别为0.965和0.912表明可靠性高且一致性好。结论:Andrews要素Ⅱ的GALL线测量，运用CBCT影像结合Dolphin软件转化头颅侧位片及相应的测量设计方法具有较好的一致性和可重复性，可应用于临床正畸。

abstractsObjective:Combining with cone-beam computed tomography (CBCT) and the CBCT-generated cephalograms by Dolphin software to measure the reproducibility of the goal anterior limit line (GALL) in the Andrews Element Ⅱ.Methods:The CBCT-generated cephalograms by Dolphin software of 57 orthodontic patients were measured according to the method we designed by Andrews' element Ⅱ to acquire the acute angle formed between the clinical forehead's surface and the forehead's anterior limit line (FALL) and the distance between the facial-axis point (FA) points of maxillary central incisors to the GALL. All above operations were performed by three doctors who had received the training of software measurement and had orthodontic expertise. Each observer had repeated twice with the time interval of 1 week. The ICC of the measurement results were used to evaluate the reproducibility for intra-observer and the consistency of the same quantitative measurement results between different observers.Results:For the measurement results of the distance between the FA points of maxillary central incisors to the GALL (a) and the angle between clinical forehead's surface and FALL (b), the ICC test showed the measurement results by the same observer operating showed good reproducibility. As for the measurement results of the distance between a and b by the three observers, the ICC test results were 0.965 and 0.912, showing good reliability and consistency.Conclusions:The measuring method of the GALL in the Andrews' element Ⅱ has good consistency and reproducibility by combining CBCT image and Dolphin-generated cephalograms, and it could be used clinically.