Li Hong, Lyu Peijun, Wang Yong, Sun Yuchun
Graduate student, Graduate Prosthodontics, Center of Digital Dentistry, Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, Research Center of Engineering and Technology for Digital Dentistry of Ministry of Health, Beijing Key Laboratory of Digital Stomatology, Beijing, China.
Professor, Center of Digital Dentistry, Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, Research Center of Engineering and Technology for Digital Dentistry of Ministry of Health, Beijing Key Laboratory of Digital Stomatology, Beijing, China.
J Prosthet Dent. 2017 Jan;117(1):93-101. doi: 10.1016/j.prosdent.2016.04.008. Epub 2016 Jul 25.
Limited information is available regarding the influence of object translucency on the scanning accuracy of a powder-free intraoral scanner.
The purpose of this in vitro study was to evaluate the scanning accuracy of a confocal microscopy principle powder-free intraoral scanner on ceramic copings and to analyze the relationship between scanning accuracy and object translucency.
Six slice specimens (12×10 mm) and 6 offset copings (1.00-mm thickness) were made from different translucent homogeneous ceramic blocks (CEREC Blocs, S0-M to S5-M, highest to lowest translucency). The primary sintered zirconia offset coping was produced in the same way as the control. Optical parameters related to the translucency of each slice were measured with a spectrophotometer. Three-dimensional (3D) datasets of the surface morphology of offset copings were obtained by using the intraoral scanner. The same white wax resin bases were used for registration. Quantitative parameters of scanning trueness and precision were measured. One-way ANOVA was used to analyze the values of each parameter among the 6 ceramic blocks. Bivariate correlation was used to analyze the relationships between each parameter of scanning accuracy and translucency (α=.05).
Translucent copings showed a positive 3D bias (S0-M to S5-M: 0.149 ±0.038 mm to 0.068 ±0.020 mm), a narrower collar diameter (Dd=-0.067 mm), larger convergence angle (ΔΦ=2.79 degrees), and larger curvature radius of the internal gingivoaxial corner (Δρ=0.236 mm). The smaller the percentage sum of scattering and absorption, the greater was the occurrence of scanning bias (r=-0.918) and curvature (r=-0.935) decrease.
Use of the tested powder-free intraoral scanner, higher translucency objects (greater translucency than S1-M/A1C) resulted in lower scanning accuracy and morphological changes. Therefore, more suitable methods of measurement are still required.
关于无粉口腔内扫描仪的扫描精度受物体透明度影响的信息有限。
本体外研究旨在评估基于共聚焦显微镜原理的无粉口腔内扫描仪对陶瓷基底冠的扫描精度，并分析扫描精度与物体透明度之间的关系。
从不同透明度的均质陶瓷块（CEREC Blocs，S0-M至S5-M，透明度从高到低）制作六个切片标本（12×10毫米）和六个偏移基底冠（厚度1.00毫米）。以与对照相同的方式制作初次烧结的氧化锆偏移基底冠。用分光光度计测量与每个切片透明度相关的光学参数。使用口腔内扫描仪获取偏移基底冠表面形态的三维（3D）数据集。使用相同的白色蜡树脂基底进行配准。测量扫描准确性和精度的定量参数。采用单因素方差分析来分析六个陶瓷块中每个参数的值。采用双变量相关性分析扫描精度的每个参数与透明度之间的关系（α = 0.05）。
透明基底冠显示出正向的3D偏差（S0-M至S5-M：0.149±0.038毫米至0.068±0.020毫米）、更窄的颈部直径（Dd = -0.067毫米）、更大的会聚角（ΔΦ = 2.79度）以及更大的内部牙龈轴角曲率半径（Δρ = 0.236毫米）。散射和吸收的百分比总和越小，扫描偏差（r = -0.918）和曲率（r = -0.935）降低的发生率就越高。
使用经测试的无粉口腔内扫描仪时，对于更高透明度的物体（透明度高于S1-M/A1C），扫描精度会降低且会出现形态变化。因此，仍需要更合适的测量方法。
