Objective: To explore the effect of scanning methods on finish line trueness of the full crown preparation. Methods: The standard full crown preparation model of the right maxillary first molars was prepared by using the maxillary standard resin dentition model. The standard preparation was scanned by imetric scanner and data were used as the true value. CEREC Omnicam and 3Shape TRIOS were used to scan the standard preparation. According to the scanning methods, they were divided into parallel scanning group, occlusal wave scanning group and buccolingual wave scanning group. Each group was scanned repeatedly 6 times. The data were imported into Geomagic Studio 2013 software, and the local finish line image data of the mesial, distal, buccal and lingual regions of the full crown preparation were extracted respectively. Three-dimensional deviation analysis was performed with the reference true value, and the root- mean-square error (RMSE) was the evaluation index of scanning trueness. The statistical method was one-way ANOVA. Results: Parallel scanning group: in general, the RMSE value of complete finish lines of scanner B [(35±6) μm] was significantly lower than that of scanner A [(44±7) μm](P<0.05). After scanner A occlusal wave scanning, the RMSE values of the mesial and distal finish lines [(33±5) and (50±12) μm] were significantly lower than those of parallel scanning group (P<0.05). After buccal and lingual wave scanning, the RMSE values of local finish lines in the mesial, distal, buccal and lingual regions [(37±3), (50±6), (28±6) and (29±8) μm] were significantly lower than those in parallel scanning group [(45±9), (63±7), (38±3) and (40±3) μm] (P<0.05). No significant difference was found in the RMSE values of the mesial, distal, buccal and lingual regions of scanner B between parallel scanning group, occlusal wave scanning group and buccolingual scanning group (P>0.05). Conclusions: The scanning trueness of the full crown preparation finish line obtained by the active triangulation scanning equipment can be improved by changing the scanning method to wave scanning.
目的： 通过分析扫描方式对全冠预备体终止线扫描正确度的影响，探索提高全冠预备体终止线局部区域扫描正确度的方法。 方法： 选择上颌标准树脂牙列模型1个，于右上第一磨牙上制备全冠预备体，作为标准参照模型，以牙颌模型扫描仪扫描获得的数据作为参考数据。分别采用主动三角测量原理的口内扫描仪A（CEREC Omnicam）和共聚焦显微成像原理的口内扫描仪B（3Shape TRIOS）扫描全冠预备体，按照扫描方式分为3组：平移式扫描组、(牙合)面波浪式扫描组和颊舌面波浪式扫描组。每组均重复扫描6次，数据导入Geomagic Studio 2013软件，分别提取全冠预备体终止线整体以及近中、远中、颊侧、舌侧图像数据，与参考数据进行三维偏差分析，以均方根误差（root-mean- square error，RMSE）作为扫描正确度的评价指标，RMSE值越小，扫描正确度越大。采用单因素方差分析进行组间比较。 结果： 对于平移式扫描组，口内扫描仪B终止线整体RMSE值［（35±6）μm］显著小于口内扫描仪A［（44±7）μm］（P<0.05）。对于口内扫描仪A，(牙合)面波浪式扫描组终止线近中和远中RMSE值［分别为（33±5）和（50±12）μm］均显著小于平移式扫描组相应区域（P<0.05）；颊舌面波浪式扫描组终止线近中、远中、颊侧、舌侧RMSE值［分别为（37±3）、（50±6）、（28±6）和（29±8）μm］均显著小于平移式扫描组相应区域［分别为（45±9）、（63±7）、（38±3）和（40±3）μm］（P<0.05）。对于口内扫描仪B，(牙合)面和颊舌面波浪式扫描组终止线4个区域RMSE值与平移式扫描组相应区域的差异均无统计学意义（P>0.05）。 结论： 波浪式扫描方式可提高主动三角测量原理扫描设备对全冠预备体终止线的扫描正确度。.