螺旋CT牙体表面成像对骨内埋伏牙的定位及临床应用

目的：建立牙齿立体表面形态图像并探讨用于术前检查骨内埋伏牙的效果。方法：应用三维螺旋ＣＴ的图像处理功能，在牙颌骨表面重建图像的基础上，采用图像处理表面遮盖法，消除周围骨组织的影像，获得单纯牙体表面图像。应用该方法检查９例患的骨内埋伏多生牙和阻生牙。结果：能清楚显示上颌骨埋伏多生牙的畸形形态、在牙列唇侧或腭侧的位置及与牙列牙根的关系；上颌埋伏恒尖牙萌出方向与正畸牵引方向的角度；阻生智齿与第二磨牙的

Three-dimensional Surface Reconstruction of Spiral CT for Teeth and Clinical Use in Examining Impacted Teeth of Jaws

Objective: To establish a new technique for three dimensional surface reconstruction of teeth (dental surface reconstruction), and apply it to investigate impacted teeth in bone before operation. Methods: On the basis of three dimensional surface reconstruction of teeth and jaws, the dental surface reconstruction is obtained with the technique of shaded surface display (SSD), making transparent bone around. This technique is applied to investigate 9 cases of supernumerary and impacted teeth. Results: Dental surface reconstruction image can present the dental surface image including crown, root, neck and root bifurcation in three dimensional way, without presenting the image of other tissue around. In 4 cases, the abnormal configuration, labial or palatal location, and relation with dentition in anterior maxilla of 5 supernumerary were shown. In 1 case, the shape, location, eruption orientation and the angle of orthodontic distraction of 1 impacted permanent canine were displayed. In 3 cases, the shape, location, and extraction resistance of 6 impacted wisdom teeth were revealed. In 1 case, the configuration, distance to adjacent molar of 1 impacted wisdom tooth, which is a transposition tooth in maxillary sinus, were also demonstrated. Conclusion: The dental surface reconstruction is a new technique to display three dimensional surface configuration of teeth. This technique can be applied to examine impacted and supernumerary teeth before surgical and orthodontic treatment.