Dai F F, Liu Y, Xu T M, Chen G
Second Clinical Division, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100101, China.
Department of Orthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2018 Apr 18;50(2):271-278.
To explore a cone beam computed tomography (CBCT)-independent method for mandibular digital dental cast superimposition to evaluate three-dimensional (3D) mandibular tooth movement after orthodontic treatment in adults, and to evaluate the accuracy of this method.
Fifteen post-extraction orthodontic treatment adults from the Department of Orthodontics, Peking University School and Hospital of Stomatology were included. All the patients had four first premolars extracted, and were treated with straight wire appliance. The pre- and post-treatment plaster dental casts and craniofacial CBCT scans were obtained. The plaster dental casts were transferred to digital dental casts by 3D laser scanning, and lateral cephalograms were created from the craniofacial CBCT scans by orthogonal projection. The lateral cephalogram-based mandibular digital dental cast superimposition was achieved by sequential maxillary dental cast superimposition registered on the palatal stable region, occlusal transfer, and adjustment of mandibular rotation and translation obtained from lateral cephalogram superimposition. The accuracy of the lateral cephalogram-based mandibular digital dental cast superimposition method was evaluated with the CBCT-based mandibular digital dental cast superimposition method as the standard reference. After mandibular digital dental cast superimposition using both methods, 3D coordinate system was established, and 3D displacements of the lower bilateral first molars, canines and central incisors were measured. Differences between the two superimposition methods in tooth displacement measurements were assessed using the paired t-test with the level of statistical significance set at P<0.05.
No significant differences were found between the lateral cephalogram-based and CBCT-based mandibular digital dental cast superimposition methods in 3D displacements of the lower first molars, and sagittal and vertical displacements of the canines and central incisors; transverse displacements of the canines and central incisors differed by (0.3±0.5) mm with statistical significance.
The lateral cephalogram-based mandibular digital dental cast superimposition method has the similar accuracy as the CBCT-based mandibular digital dental cast superimposition method in 3D evaluation of mandibular orthodontic tooth displacement, except for minor differences for the transverse displacements of anterior teeth. This method is applicable to adult patients with conventional orthodontic treatment records, especially the previous precious orthodontic data in the absence of CBCT scans.
探索一种独立于锥形束计算机断层扫描（CBCT）的下颌数字化牙模叠加方法，以评估成人正畸治疗后下颌牙齿的三维（3D）移动情况，并评估该方法的准确性。
纳入北京大学口腔医学院正畸科的15例拔牙后正畸治疗的成人患者。所有患者均拔除了四颗第一前磨牙，并采用直丝弓矫治器进行治疗。获取治疗前和治疗后的石膏牙模及颅面部CBCT扫描图像。通过三维激光扫描将石膏牙模转换为数字化牙模，并通过正交投影从颅面部CBCT扫描图像生成侧位头影测量片。基于侧位头影测量片的下颌数字化牙模叠加通过在上颌稳定区域进行连续上颌牙模叠加、咬合转移以及从侧位头影测量片叠加中获得的下颌旋转和平移调整来实现。以基于CBCT的下颌数字化牙模叠加方法作为标准参考，评估基于侧位头影测量片的下颌数字化牙模叠加方法的准确性。使用两种方法进行下颌数字化牙模叠加后，建立三维坐标系，并测量双侧下颌第一磨牙、尖牙和中切牙的三维位移。使用配对t检验评估两种叠加方法在牙齿位移测量上的差异，设定统计学显著性水平为P<0.05。
基于侧位头影测量片的和基于CBCT的下颌数字化牙模叠加方法在下颌第一磨牙的三维位移以及尖牙和中切牙的矢状和垂直位移方面未发现显著差异；尖牙和中切牙的横向位移相差（0.3±0.5）mm，具有统计学显著性。
基于侧位头影测量片的下颌数字化牙模叠加方法在评估下颌正畸牙齿位移的三维情况时，与基于CBCT的下颌数字化牙模叠加方法具有相似的准确性，除了前牙横向位移存在微小差异。该方法适用于有常规正畸治疗记录的成年患者，尤其是在没有CBCT扫描的情况下既往有珍贵正畸数据的患者。
