16排螺旋CT三维重建技术在埋伏牙定位中的合理应用

The Application of Three-dimensional Reconstruction Technique of Multi-slices Spiral CT in Examining Embeded Teeth in Jaws

目的探讨螺旋CT三维重建技术在埋伏牙定位中的合理应用方法。方法37例患者均行曲面体层片和多层螺旋CT轴位扫描,层厚1.25 mm,采用最大密度投影(MIP)、表面遮盖显示(SSD)和多平面重建(MPR)技术对图像进行重建。将横轴位图像与不同重建的图像进行对比。结果SSD可以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能显示牙齿全貌、牙齿纵向排列关系;MPR则对根尖骨质、根尖与牙槽骨的局部关系显示更清晰。在37例中均能清晰显示牙齿的位置、数目以及与邻牙的关系,但有15例对根尖的弯曲程度以及多根牙的根分叉显示不够清晰。曲面体层片显示3例位于上颌窦内,2例上颌后牙颊舌向水平埋伏阻生。结论对怀疑有埋伏牙的患者,均先作曲面体层片检查,如临床需要精确图像(如正畸等)才作多层螺旋CT扫描。

Objective To study the ideal method of three-dimensional reconstruction technique of multi-alices spiral CT（MSCT 16F） in examining embeded teeth in jaws. Methods 37 cases were examined by orthopantomography and helical scanning of multi-sllces spiral CT with 1.25 mm slice thickness. The cr images were reconstructed by magnum intensity projection （MIP）, shaded display （SSD） and multi-planar reconstructions （MPR）, and compared with which obtained by scanning in axial projection. Results By MIP, SSD and MPR reconstruction, most information including the position, number and direction af tooth axial shape d tooth body d 37 cases embeded teeth can be displayed clearly. However, the curve and furcation of tooth d 15 cases was not distinct enough. It＇ s displayed in orthopantomography that 3 teeth impacted in maxillary sinus and 2 cases of maxillary molars were buccolingually and horizontally impacted. Conclusion It＇s recommended orthopantomography should be applied as the first choice for the patient with embeded teeth, and 3D reconstruction technique could be used as an complementary mean when move exact detail is needed.