Guo D N, Pan S X, Heng M D, Qu J, Wei X X, Zhou Y S
Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China.
Dental Laboratory, Peking University School and Hospital of Stomatology & National Clinical Research Center for Oral Diseases & 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. 2020 Dec 24;53(1):83-87. doi: 10.19723/j.issn.1671-167X.2021.01.013.
To compare the registration accuracy of three-dimensional (3D) facial scans for the design of full-arch implant supported restoration by five methods and to explore the suitable registration method.
According to the criteria, ten patients with maxillary edentulous jaw or end-stage dentition requiring implant supported restorations were enrolled in this study. A special rim with individual feature marks reflected appropriate occlusal relationship and esthetic characteristics was made for each patient. Both 3D facial scan data of natural laughter and with opener traction to expose the teeth or occlusal rim of each patient were acquired by facial scan and input to the digital analysis software Geomagic Qualify 2012. The dataset was superimposed by five different methods: seven facial anatomical landmark points alignment, facial immobile area alignment (forehead and nasal area), facial anatomical landmark points and immobile area combining alignment, facial feature points alignment, facial and intraoral feature points alignment with the same local coordinate system. The three-dimensional deviation of the same selected area was calculated, the smaller the deviation, the higher the registration accuracy. The 3D deviation was compared among the three registration methods of facial anatomical landmark points, facial immobile area alignment and the combination of the above two methods. Friedman test was performed to analyze the difference among the three methods (α=0.05). The effect of the aid of the facial and intraoral feature points were evaluated. Paired test were performed to analyze the difference (<0.05).
The average three-dimensional deviation of the selected area after alignment with the facial anatomical landmarks was (1.501 2±0.406 1) mm, significantly larger than that of the facial immobile area best-fit alignment [(0.629 1±0.150 6) mm] and the combination of the two methods[(0.629 1±0.150 6) mm] ( < 0.001). The aid of the facial feature points could significantly reduce the deviation (=1.001 3, < 0.001). There was no significant statistical difference in the remaining groups.
The forehead area of the 3D facial scan can be exposed as much as possible. The establishment of facial characteristic landmark points and the use of the invariant area alignment can improve the accuracy of registration. It should be clinically feasible to apply three-dimensional facial scan to the design of full-arch implant supported restoration with the registration of the immobile area on the face especially the forehead area.
比较五种方法进行三维（3D）面部扫描用于全牙弓种植支持修复体设计的配准精度，并探索合适的配准方法。
根据纳入标准，本研究纳入了10例上颌无牙颌或晚期牙列缺失需种植支持修复的患者。为每位患者制作了带有反映合适咬合关系和美学特征的个性化特征标记的特殊牙合堤。通过面部扫描获取每位患者自然笑时以及使用开口器牵引暴露牙齿或牙合堤时的3D面部扫描数据，并输入到Geomagic Qualify 2012数字分析软件中。数据集通过五种不同方法进行叠加：七个面部解剖标志点对齐、面部固定区域对齐（额头和鼻区）、面部解剖标志点与固定区域组合对齐、面部特征点对齐、面部与口内特征点在同一局部坐标系下对齐。计算同一选定区域的三维偏差，偏差越小，配准精度越高。比较面部解剖标志点、面部固定区域对齐以及上述两种方法组合这三种配准方法之间的三维偏差。采用Friedman检验分析三种方法之间的差异（α = 0.05）。评估面部和口内特征点辅助的效果。采用配对检验分析差异（<0.05）。
与面部解剖标志点对齐后选定区域的平均三维偏差为（1.501 2±0.406 1）mm，显著大于面部固定区域最佳拟合对齐的偏差[（0.629 1±0.150 6）mm]以及两种方法组合的偏差[（0.629 1±0.150 6）mm]（<0.001）。面部特征点的辅助可显著降低偏差（=1.001 3，<0.001）。其余组间无显著统计学差异。
3D面部扫描应尽可能多地暴露额头区域。建立面部特征标志点并采用固定区域对齐可提高配准精度。将三维面部扫描应用于全牙弓种植支持修复体设计，并对面部尤其是额头区域的固定区域进行配准，在临床上应是可行的。
