螺旋CT扫描在牙齿正畸中的临床应用价值

Clinical application of helical CT 3D reconstruction for the dental orthopaedics

目的探讨螺旋CT三维(3D)重建技术在牙齿正畸中的临床应用价值。方法41例牙齿正畸的患者行螺旋CT轴面扫描,层厚30mm。采用最大密度投影法(MIP),表面遮盖法(SSD)和多层面重建法(MPR)3种方式重建图像。将横轴面图像与不同方法重建的图像之间相互比较。结果41例中37例见牙体长轴排列不整齐,倾斜、旋转、重叠,牙齿长轴间距离不等,其中25例共有36颗埋伏牙。横轴面图像包括全部信息。SSD显示牙齿与颌骨的外部轮廓、整体形态以及牙齿排列与颌骨之间的关系。MIP清楚显示牙齿全貌、牙齿纵向排列关系,显示颌骨内埋伏牙36颗,通过旋转角度显示埋伏牙位置、形态,其中位于牙列的腭侧29颗,唇侧7颗。MPR对根尖骨质、根尖与牙槽骨的局部关系显示更清晰。结论螺旋CT3D重建是1种能展示牙齿立体形态影像的新技术。轴面图像、MIP、SSD及MPR联合应用能明确病变性质,立体、直观、多方位提供临床医师所需信息,有利于治疗方案的选择。

Objective To evaluate the clinical application of helical CT 3D reconstruction technique in the dental orthopaedics. Methods The helical CT was performed with 3.0 mm slice thickness and 1.0 pitch in 41 patients with dental orthopaedics. The 3D reconstructions, including maximum intensity projection (MIP), surface shaded display (SSD), and multiplanar reconstructions (MPR), were made for all the cases. Results Thirty-seven of the 41 patients showed malalignment, tilt, rotation, overlap of the teeth and the different space between the longitudinal axes of the teeth. Twenty-five cases of them have shown 36 buried teeth in all. The axial images covered all the information. SSD demonstrated the external contours and entire morphologies of the teeth and the mandible with the relationship of the teeth alignment and the mandible. MIP clearly manifested the full view and the longitudinal alignment of the teeth. Among the 36 buried teeth, there were 29 palatally and 7 labially presented teeth, and they were morphologically delineated on MIP through various angles. Conclusion The helical CT 3D reconstruction is a new technique to display the stereoscopic configuration of teeth. The combination of axial images and MIP, SSD, and MPR provides valuable anatomic and diagnostic information helpful for the surgeons to structure and determine the treatment protocol for the dental orthopaedics.