锥形束CT在下颌阻生第三磨牙拔除术前诊断应用的初步研究

Pilot clinical study of the dental cone beam CT examination before the impacted mandibular third molar extraction

目的评价口腔颌面锥形束CT（codebeamCT，CBCT）确定下颌阻生第了磨牙（impacted mandibular third molar，IMTM）与下牙槽神经管位置关系，为IMTM拔除术中预防下牙槽神经损伤提供临床依据。方法通过IMTM拔除术前曲面体层x线片检查，筛选出IMTM与下牙槽神经管存在较大范嗣接触或部分重叠影像表现的49例患者（60侧），进一步行CBCT检查，结合种植机微动力系统微创拔牙术中观察结果，应用诊断试验的方法评价术前CBCT检佥结果的准确性。结果术前CBCT观察IMTM突破下牙槽神经管壁判断的灵敏度82．8％、特异度87．0％，Youden指数0．69，阳性预测值88．9％，阴性预测值80．0％。两位口腔放射医师术前对CBCT共同判读的结果与术中观察结果的符合率为84．6％（44／52）。对两位医师术前分别判读CBCT影像的结果进行一致性分析，Kappa值=0．80。结论对于曲面体层x线片显示IMTM与下牙槽神经管存在较大范围接触或部分重叠影像表现的病例应用CBCT术前检查，CBCT显示的IMTM与下牙槽神经管的关系与临床实际观察结果一致性较高。

Objective To evaluate the diagnostic accuracy of the cone beam computed tomography （CBCT） in judging the relationship between the impacted mandibular third molar （IMTM） and the interior alveolar canal （IAC）. Methods Sixty IMTM superimposing on the canal partially or touching the canal in line on panoramic radiograms were examined by CBCT. All CBCT images of these cases were observed by two dentists respectively. Then, all these IMTM were extracted by minimally invasive surgery, and the conditions of the IMTM sockets were observed. Two dentists observed the CBCT images independently and reached a consensus. Diagnosis test was performed in this study. Results Eight IMTM sockets were bleeding during the extracted operation, and whether the IAC wall was broken could not be judged. The other 52 1MTM sockets were clear and the walls of IAC were broken in 29 IMTM extractions. The sensitivity, specificity, Youden index, positive predictive value and negative predictive value of CBCT were 82.8% , 87.0% , 88.9% and 80.0% respectively. The diagnostic accuracy judged by the two dentists and Kappa coefficient were calculated as 84. 6% and 0. 800. Conclusions The CBCT examination had good authenticity and reliability, and it was very helpful in predicting the actual relationship between the IMTM and IAC.