Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Egypt.
Department of Fixed Prosthodontics, Faculty of Dentistry, British University, Egypt.
J Prosthodont. 2020 Dec;29(9):800-804. doi: 10.1111/jopr.13202. Epub 2020 Jun 7.
To evaluate the influence of preparation design and tooth geometry on the accuracy of scans obtained from three different intraoral scanners (IOS).
Full coverage crown and inlay preparations with known axial wall tapers (6ᵒ and 12ᵒ) were performed on typodont teeth using a computer numerical control machine. Reference models were scanned with a highly accurate reference scanner (Ineos X5) and saved in standard tessellation language (STL) format then each IOS (Omnicam, Trios, and i500) scanned each model 10 times. The STL files obtained from the intraoral scanners were compared to the reference models (trueness) and within each test group (precision). Data were statistically analyzed using three- way ANOVA and one- way ANOVA.
When comparing trueness values extracoronal preparations (32.30 ± 11.23 µm) was significantly better than intra-coronal preparation (59.61 ± 16.42 µm). As for opposing wall taper, one-way ANOVA revealed that the more the convergence or divergence between opposing walls the better is the trueness. Significant differences were observed between the scanners. 3 Shape Trios (35.70 ± 14.12 µm) and medit i500 (44.31 ± 11.41 µm) showed no statistically significant differences. However, both showed significantly better precision results when compared to Omnicam (57.83 ± 22.14 µm).
Extracoronal preparations show better trueness and precision in comparison to intracoronal preparations. Trios and i500 have better trueness and precision than Omnicam. Increasing the taper of the axial wall has a direct effect on trueness of scans obtained from the IOS.
评估三种不同口内扫描仪（IOS）的预备设计和牙齿几何形状对扫描精度的影响。
使用数控机床在仿头牙上制作具有已知轴向壁锥度（6°和 12°）的全冠和嵌体预备体。使用高精度参考扫描仪（Ineos X5）对参考模型进行扫描，并以标准 tessellation language（STL）格式保存，然后每个 IOS（Omnicam、Trios 和 i500）扫描每个模型 10 次。从口内扫描仪获得的 STL 文件与参考模型（准确性）和每个测试组（精度）进行比较。使用三因素方差分析和单向方差分析对数据进行统计学分析。
在比较外冠预备体的准确性值时（32.30 ± 11.23 µm）明显优于内冠预备体（59.61 ± 16.42 µm）。对于相对壁锥度，单因素方差分析表明，相对壁之间的收敛或发散程度越大，准确性越好。扫描仪之间存在显著差异。3Shape Trios（35.70 ± 14.12 µm）和 medit i500（44.31 ± 11.41 µm）之间无统计学差异。然而，与 Omnicam（57.83 ± 22.14 µm）相比，它们的精度结果都要好得多。
与内冠预备体相比，外冠预备体的准确性和精度更好。Trios 和 i500 的准确性和精度优于 Omnicam。轴向壁锥度的增加对 IOS 获得的扫描准确性有直接影响。
