Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan.
Department of Biomaterials Science, Osaka University Graduate School of Dentistry, Osaka, Japan.
J Prosthodont. 2022 Jan;31(1):59-64. doi: 10.1111/jopr.13358. Epub 2021 May 29.
To assess the influence of liquid attached on the tooth surfaces on the accuracy (trueness and precision) of intraoral scanners and the effectiveness of the drying method (using compression air) to exclude the influence of liquid on the scanning results.
A mandibular jaw model was scanned using an industrial computed tomography scanner to obtain a reference model. A scanning platform was designed to simulate three specific tooth surface states (dry, wet, blow-dry). Two kinds of liquids (ultra-pure water and artificial saliva) were used for the test. Two intraoral scanners (Trios 3 and Primescan) were used to scan the mandibular jaw model 10 times under each condition. All scanning data were processed and analyzed using dedicated software (Geomagic Control 2015). Trueness and precision comparison were conducted within the 12 groups of 3D models divided based on different intraoral scanners and liquids used under each condition. The root mean square (RMS) value was used to indicate the difference between the aligned virtual models. The color maps were used to evaluate and observe the deviation distribution patterns. The 3-way ANOVA (condition, intraoral scanner, liquid) followed by the Tukey test were used to assess precision and trueness. The level of significance was set at 0.05.
The mean RMS values obtained from wet condition were significantly higher than those of the dry and blow-dry condition (p < 0.001, F = 64.033 for trueness and F = 54.866 for precision), which indicates less accurate trueness and precision for wet condition. For two different types of liquids, the mean RMS value was not significantly different on trueness and precision. The deviations caused by liquid were positive and mainly distributed in the pits and fissures of the occlusal surface of posterior teeth, the interproximal area of the teeth, and the margin of the abutments.
Liquid on the tooth surface could affect intraoral scanning accuracy. Blow-drying with a three-way syringe can reduce scanning errors.
评估牙面附着物对口腔内扫描仪准确性（准确性和精密度）的影响，以及干燥方法（使用压缩空气）排除液体对扫描结果影响的有效性。
使用工业计算机断层扫描 (CT) 扫描仪对下颌模型进行扫描，以获得参考模型。设计了一个扫描平台来模拟三种特定的牙面状态（干燥、湿润、吹干）。使用两种液体（超纯水和人工唾液）进行测试。使用两种口腔内扫描仪（Trios 3 和 Primescan）在每种条件下对下颌模型进行 10 次扫描。使用专用软件（Geomagic Control 2015）对所有扫描数据进行处理和分析。在每个条件下使用不同的口腔内扫描仪和液体对 12 组 3D 模型进行分组，对准确性和精密度进行比较。均方根 (RMS) 值用于表示对齐虚拟模型之间的差异。使用颜色图评估和观察偏差分布模式。采用三因素方差分析（条件、口腔内扫描仪、液体），然后采用 Tukey 检验评估准确性和精密度。显著性水平设定为 0.05。
湿润条件下获得的平均 RMS 值明显高于干燥和吹干条件下的 RMS 值（p < 0.001，准确性的 F 值为 64.033，精密度的 F 值为 54.866），这表明湿润条件下准确性和精密度较低。对于两种不同类型的液体，在准确性和精密度方面，平均 RMS 值没有显著差异。液体引起的偏差为正值，主要分布在后牙牙合面的窝沟、牙齿邻面和基牙边缘。
牙面附着物会影响口腔内扫描的准确性。使用三向注射器吹干可以减少扫描误差。
