螺旋CT三维重建在上颌骨正畸埋伏牙诊断中的临床应用

目的评价CT三维重建在上颌骨正畸埋伏牙中的诊断价值。方法对常规口腔全景片和咬合片不能清楚判断的47例上颌骨内埋伏牙患者行螺旋CT扫描和图像三维重建,并采用多平面重建(MPR)、三维牙体表面成像(SSD)及上颌骨和牙体容积成像(VR)显示埋伏牙的形态、位置及与邻牙的关系。结果47例均清楚显示了埋伏牙的形态、唇腭向位置、萌出方向及与邻牙的关系,MPR可测出埋伏牙的高度,SSD能清晰地显示骨内埋伏牙的形态、在牙列唇侧或腭侧的位置及与牙列牙根的关系,VR可展现埋伏牙的萌出方向及与邻牙的空间关系。结论SSD和VR成像对上颌骨埋伏牙可互为补充,立体直观地、完整地显示其病理解剖关系,是一种准确有效的检查方法。

Assessment of spiral CT and 3-dimensional image in diagnosis of maxillary pseudoanodotia

Objective To assess the diagnostic value of spiral CT and 3-dimensional image in diagnosis of maxillary pseudoanodotia.Methods Forty-seven patients whose impacted teeth couldn' t be judged clearly through the panorama and occlusal with maxillary pseudoanodotia were scanned with 1 mm collimation,reconstruction interval 1 mm and pitch of 1-3.Original data obtained with transaxial images were transferred to workstation and postprocessed with multiplane reconstruction(MPR),surface shading display(SSD)and volumetric rendering(VR).Results Three-dimensional surface reconstruction of spiral CT could clearly demonstrate the dental surface image including crown,root bifurcation in three-dimensional way,labial or palatal location,eruption orientation and relation with dentition.MPR image can present the pseudoanodotia highness.SSD image could reveal the dental surface image including crown,root,neck and root bifurcation in three-dimensional way,and the abnormal configuration,labial or palatal location,and relation with dentition in anterior maxilla,without presenting the image of other tissue around.VR could display the shape,location,eruption orientation,the angle of orthodontic distraction and the connection with around teeth.Conclusion 3D images with SSD and VR present a direct visualization of maxillary pseudoanodotia.Combination of both techniques provides an advantage of showing pathoanatomic relationship of maxillary pseudoanodotia.The three-dimensional surface reconstruction is an accurate and effective method to examine impacted teeth before orthodontic treatment.