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目的:评价锥形束CT对离体干下颌骨磨牙Ⅱ°根分叉病变测量的准确性。方法:利用锥形束CT(cone-beam computed tomography,CBCT)对9个干下颌骨上有Ⅱ°根分叉病变的20颗第一、第二磨牙进行检查,并测量相关的8个参数,与直接探诊测量结果、根尖片测量结果进行比较。结果:CBCT可以对全部根分叉病变进行准确分度,对于全部8个参数中的5个,CBCT和直接探诊测量结果之间的差异无统计学意义(P>0.05),而根分叉开口至骨嵴顶、骨袋底及水平骨缺损最深处距离3个参数则CBCT小于探诊结果(P<0.05),究其原因可能是两种方法对根分叉开口位置的判定不一致。两颗磨牙的根分叉病变无法通过根尖片进行诊断,且根尖片测量只能获得全部8个参数中两个参数的相关数据。结论:在体外,CBCT可以为下颌磨牙Ⅱ°根分叉病变提供较为准确、全面的三维信息。
OBJECTIVE: To evaluate the accuracy of cone beam computed tomography in the measurement of bifurcation lesions of mandibular molar Ⅱ ° in vitro. Methods: Twenty first and second molars with nine degrees of bifurcation lesions of Ⅱ ° on mandibular mandible were examined by cone-beam computed tomography (CBCT), and the related 8 parameters were measured. And direct exploration of the measurement results, root tip film measurement results were compared. Results: CBCT accurately indexed all bifurcation lesions. For 5 out of 8 parameters, there was no significant difference between CBCT and direct probing findings (P> 0.05) CBCT was smaller than that of the probe (P <0.05). The reason was that the two methods were inconsistent with the determination of the position of the root bifurcation. Root bifurcation lesions of two molars can not be diagnosed by apical slices, and the apical measurement can only get the data of the two parameters of all eight parameters. Conclusion: In vitro, CBCT can provide more accurate and comprehensive three-dimensional information for mandibular molars Ⅱ ° root bifurcation lesions.