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目的    评价锥形束CT（cone beam computed tomography，CBCT）用于颌骨内埋伏牙定位的价值。方法    选择2009年9月至2010年3月中山大学附属口腔医院诊治的，用常规口腔全景片和定位片无法清楚判断埋伏牙形态、大小及与邻牙位置关系的颌骨内埋伏牙患者28例。所有患者行CBCT扫描，对所得数据处理后获得牙体表面三维立体图像及任意平面图像和任意曲面断层图像。结果        CBCT从多个角度完整清晰地显示埋伏牙的形态、大小、萌出方向、唇腭侧位置及与邻牙位置的关系。根据CBCT图像，18例26颗埋伏牙采用相应的手术进路拔除，10例10颗形态正常且非倒置的埋伏牙采用去骨开窗正畸治疗。所有患者顺利完成手术，术前诊断与术中判断完全一致，准确率为100%。术后创口均Ⅰ期愈合，无感染、邻牙损伤等并发症发生。结论    CBCT可直接、准确地反映埋伏多生牙的位置，为临床诊断和治疗提供可靠信息。

Clinical application of cone beam computed tomography to the diagnosis and therapy of embedded teeth in jaws

Objective To evaluate the value of cone beam computed tomography in locating the embedded teeth in jaws. Methods From September 2009 to March 2010, 28 patients （15 males and 13 females, aged from 9 to 33 with the mean of 14.2 years）, whose embedded tooth＇s shape, size and relation with adjacent teeth couldn＇t be judged clearly ac- cording to the panorama and locating films, were scanned by cone beam computed tomography. The three-dimensional images, multiplane reconstruction and panoramic images from different directions were obtained after original data was processed by workstation. Results The dental surface shape, size, eruption orientation, labial or palatal location, and relation with adjacent teeth of the embedded tooth in jaws could be demonstrated clearly by the images of cone beam CT, and with the help of these images of cone beam CT, 26 embedded teeth were successfully extracted by the appropriate surgical approach for supernumerary teeth, distorted teeth and inverted teeth in 18 patients, while 10 embedded teeth of non- inverted teeth were done by orthopedics in 10 patients. The diagnoses were completely confirmed by surgery with accuracy of 100% in all cases. All patients were well healed with no infection and injury to adjacent teeth. Conclusion Cone beam CT images can provide direct and accurate images of the location of the embedded tooth, which provides dependable information for clinical diagnosis and therapy.