目的: 比较无牙颌种植修复设计三维面部扫描配准的5种方法的配准精度,探究适宜的配准方法。方法: 依据标准共纳入10名受试者,每位受试者戴有具有特征标志点的蜡堤。利用FaceScan三维面部扫描仪获取10位拟行无牙颌种植修复患者的自然大笑位和开口器牵拉暴露口内蜡堤的三维面部扫描数据,将扫描数据导入数字化分析软件Geomagic Qualify 2012中,建立局部坐标系,分别利用面部解剖标志点对齐、面部不动区域对齐、面部点对齐与区域对齐结合、增加面部特征点对齐、增加面部和口内特征标记对齐5种方法将两个面部扫描数据重合,计算同一选定区域的三维偏差,三维偏差越小代表配准精度越高。采用SPSS22.0软件进行统计学分析,面部解剖标志点对齐、面部不动区域对齐、面部点对齐与区域对齐结合3组间差异进行Frideman检验,是否增加面部特征点对齐和是否增加口内特征标记对齐的两组进行配对t检验比较。结果: 直接选择面部解剖标志点对齐[(1.501 2±0.406 1) mm],面上1/3选中区域三维偏差平均值显著大于面部不动区域对齐[(0.629 1±0.150 6) mm]及两种方法相结合[(0.603 5±0.493 4) mm]的偏差(P<0.001);增加面部特征点可显著减小配准后偏差(t=1.001 3, P<0.001),其余组间差异无统计学意义。结论: 面上1/3不动区域应用于无牙颌种植修复设计的三维面部扫描配准是临床可行的,面部扫描操作时可尽量暴露前额区域,增加面部特征点,并利用面部不动区域最佳拟合对齐提高配准精度。

Objective: 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.Methods: 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 t test were performed to analyze the difference (P<0.05).Results: 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] (P<0.001). The aid of the facial feature points could significantly reduce the deviation (t=1.001 3, P<0.001). There was no significant statistical difference in the remaining groups.Conclusion: 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.