Statement of problem

The triple-scan method for assessing the 3D adaptation of dental restorations has been introduced and reported to be reliable. However, the suitability of using a dental laboratory scanner in the triple-scan method has not been evaluated.

Purpose

The purpose of this in vitro study was to evaluate the suitability of the triple-scan method using a dental laboratory scanner to assess the 3D adaptation zirconia crowns.

Material and methods

A zirconia abutment and a zirconia crown were fabricated, and the abutment was fixed in a custom-made base. The crown was seated onto the abutment with the interposition of light-body silicone impression material between them. The triple-scan method was performed by using a dental laboratory scanner, and the mean cement-gap thickness was calculated. The seating and digitalization process was repeated 10 times, and after each digitalization, the light-body silicone layer was stabilized by applying heavy-body silicone impression material over it. Cement-gap thickness was measured on cross-sections of the aligned scan data sets and of the physical silicone replica. The results were assessed by using the paired t test and the Bland-Altman method (α=.05).

Results

Mean 3D cement-gap thickness assessed by the triple-scan method reported small dispersion with a coefficient of variation of 5.6% for the occlusal area, 1.9% for the axial area, and 6.4% for the margin area. Cement gap thickness measured at corresponding locations in the aligned scan data sets and in the physical silicone replica reported no significant difference (P=.326) and good agreement.

Conclusions

The cement gap was accurately duplicated in scan data sets. The triple-scan method by using a dental laboratory scanner is suitable for assessing the 3D adaptation of zirconia crowns.

中文翻译：

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三重扫描方法与牙科实验室扫描仪的适用性，以评估氧化锆牙冠的3D适应性

问题陈述

引入了用于评估牙齿修复体3D适应性的三次扫描方法，并据报道是可靠的。但是，尚未评估在三重扫描方法中使用牙科实验室扫描仪的适用性。

目的

这项体外研究的目的是评估使用牙科实验室扫描仪评估3D氧化锆冠的三次扫描方法的适用性。

材料与方法

制作了氧化锆基台和氧化锆牙冠，并将基台固定在定制的基座中。将冠冠置于基台上，并在它们之间插入轻型有机硅印模材料。通过使用牙科实验室扫描仪进行三次扫描法，并且计算平均水泥间隙厚度。安置和数字化过程重复10次，每次数字化后，通过在其上施加重体有机硅印模材料来使轻体有机硅层稳定。在对准的扫描数据集和物理有机硅复制品的横截面上测量水泥间隙厚度。通过配对t检验和Bland-Altman方法（α= .05）评估结果。

结果

通过三重扫描法评估的平均3D水泥间隙厚度报告了较小的色散，咬合面积的变异系数为5.6％，轴向面积的变异系数为1.9％，边缘区域的变异系数为6.4％。在对齐的扫描数据集和物理有机硅仿品的相应位置处测量的水泥缝隙厚度报告无显着差异（P = .326）且吻合良好。

结论

在扫描数据集中准确地复制了水泥间隙。通过使用牙科实验室扫描仪的三次扫描方法适合评估氧化锆冠的3D适应性。