两种结构光口内三维扫描仪获取单冠预备体数据质量的模型评价

Evaluation of the quality of three-dimensional data acquired by using two kinds of structure light intra-oral scanner to scan the crown preparation model

目的 定量评价两种结构光口内三维扫描仪获取单冠预备体模型的数据质量和精度,为临床应用提供参考.方法 在上颌标准牙列模型上制备双侧中切牙、尖牙、第二前磨牙、第二磨牙标准单冠预备体.用两种结构光口内三维扫描仪（A：先临口内三维扫描仪;B：PlanScan口内三维扫描仪）扫描预备体,获得三维扫描数据,重复3次.用高精度牙颌模型三维扫描仪扫描预备体,获得真值组数据.分析3组数据质量指标（非流形边、自相交、高度折射边、钉状物、小组件、小孔）.用3D偏差分析分别测得A、B组与真值组配准后同牙位上千个数据点间的平均距离和标准差,取每组24个标准差,计算扫描数据精密度;取每组24个平均距离的绝对值,计算扫描仪正确度;每组同牙位3次重复扫描数据间进行偏差分析,计算扫描仪精密度.独立样本Mann-Whitney U检验比较两组扫描仪正确度、精密度以及扫描数据精密度的差异.对A或B组数据质量指标与扫描仪正确度、扫描数据精密度进行Spearman相关性分析.结果 A扫描仪3次扫描共得到96个钉状物,B扫描仪3次扫描共得到5个钉状物,真值组为0个.A、B扫描仪正确度分别为8.0（8.3）和9.5（11.5） μm,精密度分别为6.4（11.1）和9.6（11.7） μm,扫描数据精密度分别为27.0（17.0）和32.0（7.5） μm,两组差异均无统计学意义（P＞0.05）.相关性分析显示,A组钉状物数量与该组扫描数据精密度呈正相关（r=0.46,P=0.02）.结论 本项研究所用B扫描仪扫描数据质量优于A扫描仪,两种口内三维扫描仪的扫描精度（正确度和精密度）相当,A扫描仪扫描数据精密度可受扫描数据质量的干扰.

Objective To quantitatively evaluate the quality and accuracy of three-dimensional （3D） data acquired by using two kinds of structure intra-oral scanner to scan the typical teeth crown preparations.Methods Eight typical teeth crown preparations model were scanned 3 times with two kinds of structured light intra-oral scanner（A,B）,as test group.A high precision model scanner were used to scan the model as true value group.The data above the cervical margin was extracted.The indexes of quality including non-manifold edges,the self-intersections,highly-creased edges,spikes,small components,small tunnels,small holes and the anount of triangles were measured with the tool of mesh doctor in Geomagic studio 2012.The scanned data of test group were aligned to the data of true value group.3D deviations of the test group compared with true value group were measured for each scanned point,each preparation and each group.Independent-samples Mann-Whitney U test was applied to analyze 3D deviations for each scanned point of A and B group.Correlation analysis was applied to index values and 3D deviation values.Results The total number of spikes in A group was 96,and that in B group and true value group were 5 and 0 respectively.Trueness：A group 8.0 （8.3） μm,B group 9.5 （11.5） μm（P〉0.05）.Correlation analysis of the number of spikes with data precision of A group was r=0.46.Conclusions In the study,the qulity of the scanner B is better than scanner A,the difference of accuracy is not statistically significant.There is correlation between quality and data precision of the data scanned with scanner A.