Objective To evaluate the measurement consistency of the cephalograms from cone-beam computed tomographic ( CBCT ) volumes and conventional lateral cephalograms ( Ceph ) . Methods Thirty-one post-orthodontic patients were radiographed with CBCT and Ceph techniques. CBCT data was uploaded into Dolphing Imaging 11. 5 Premium software to generate cephalograms (CCB). 29 landmarks were plotted and were measured on CCB and Ceph by the same medical imaging technologist. Ten patients sampled randomly from the 31 patients received repeated measurement for the above 29 landmarks with a time interval of one week. Intraclass correlations ( ICC) and paired t tests were used to analyze the measurement consistency. Results The intraobserver correlations (ICC) was greater than 0. 9 for 82. 8% (24/29) of CCB assessments and 79. 3% (23/29) of Ceph assessments, and no significant difference was observed ( t=0. 762,P=0. 449). For skeletal landmarks, the values of ANS-Me, S-Go and N-Me measured with Ceph were higher than those with CCB. Similarly, the determination values of L1-NB and L1-NB from Ceph were also higher than those from CCB among the dental landmarks. Whereas for the soft tissue landmarks, the value of soft tissue convexity measured with Ceph were lower than that with CCB. Conclusion ICC is satisfactory for both CCB and Ceph. However, for some landmarks, there is still significant difference between the cephalograms from CBCT and Ceph. The measurement values should be referenced with caution for the evaluation on the effect of orthodontic treatment.%目的：评价锥形束计算机断层扫描( cone-beam computed tomography, CBCT)转化的头颅侧位片与传统头颅侧位片测量结果的一致性。方法对31位正畸治疗后患者进行CBCT扫描,同时拍摄传统头颅侧位片作为对照。利用Dolphing Imaging 11．5 Premium 软件按照统一条件将CBCT转化为头颅侧位片。选择29个标志点,由同一位测量者在两种头颅侧位片分别测量每位病人的29个参数值,间隔1周后再随机抽取10名病人重复测量上述29个参数。采用组内相关系数( ICC)评价操作者的测量信度,并采用配对t检验分析两种头颅侧位片测量结果的一致性。结果82．8%(24/29)的转化头颅侧位片测量项目ICC>0．9,79．3%(23/29)的传统头颅侧位片测量项目ICC>0．9,两种头颅侧位片的ICC无统计学差异(t=0．762,P=0．449)。骨性标志中ANS-Me、S-Go和N-Me的传统头颅侧位片测量值明显高于转化头颅侧位片的测量值；牙性标志中L1-NB和L1-NB的传统头颅侧位片测量值也明显高于转化头颅侧位片测量值；而软组织标志中,软组织面凸角值的转化头颅侧位片测量值明显高于传统头颅侧位片测量值。统计学分析结果提示上述差异均具有显著性意义。结论转化头颅侧位片和传统头颅侧位片两种头影测量方法均具有较高的组内相关系数,但是两种方法在某些标志点上的测量值之间存在差异,在利用头影测量结果进行口腔正畸疗效评价时需要慎重。
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