Statement of problem

Although digital scanning has become popular, conventional impressions with polyvinyl siloxane (PVS) are still the gold standard for fabricating indirect restorations. Studies comparing the marginal fit obtained from both techniques are sparse.

Purpose

The purpose of this in vitro study was to compare the marginal fit of zirconia copings fabricated by using a conventional impression and 2 digital scanning techniques.

Material and methods

A typodont mandibular left second premolar was prepared for a complete crown. Ten impressions were made in each experimental group: PVS group, conventional impression with PVS; TRIOS 3 group, impression with intraoral scanner TRIOS 3; and CS 3600 group, impression with intraoral scanner CS 3600. Thirty zirconia copings were fabricated with computer-aided design and computer-aided manufacturing (CAD-CAM) technology, and the marginal discrepancy was measured in 4 locations per specimen by using a stereo microscope. Additionally, the marginal discrepancy of each coping obtained in the PVS group was measured on the stone die produced, creating the PVS A group. The mean value of discrepancy was calculated for each location and each group. Statistically significant differences among the impression techniques were tested with 1-way ANOVA, repeated measures ANOVA, and the t test (α=.05).

Results

The mean ±standard deviation values of vertical marginal discrepancy were 106 ±87 μm for the PVS group, 34 ±49 μm for the PVS A group, 53 ±56 μm for the TRIOS 3 group, and 93 ±69 μm for the CS 3600 group. Statistically significant differences (P<.05) were found between the PVS group and TRIOS 3 group and between the CS 3600 group and TRIOS 3 group.

Conclusions

Digital scanning with the TRIOS 3 showed lower values of marginal discrepancy than the digital scan with the CS 3600 and conventional impression making with an elastomer.

中文翻译：

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常规印模制作和数字扫描后制作的氧化锆顶盖的边缘拟合：一项体外研究。

问题陈述

尽管数字扫描已变得很流行，但聚乙烯硅氧烷（PVS）的传统印模仍然是制造间接修复体的金标准。比较从两种技术获得的边际拟合度的研究很少。

目的

这项体外研究的目的是比较使用常规压印和2种数字扫描技术制造的氧化锆顶盖的边缘拟合。

材料与方法

准备一个完整的牙冠的下颌左前突牙。在每个实验组中产生十个印象：PVS组，PVS的常规印象；TRIOS 3组，口内扫描仪TRIOS 3印象；和CS 3600组，通过口内扫描仪CS 3600进行印模。采用计算机辅助设计和计算机辅助制造（CAD-CAM）技术制造了三十个氧化锆顶盖，并使用体视显微镜在每个样本的4个位置测量了边缘差异。另外，在生产的石材模具上测量在PVS组中获得的每个处理的边际差异，从而创建PVS A组。计算每个位置和每个组的差异平均值。使用1向ANOVA对印象技术之间的统计学差异进行了检验，t检验（α= .05）。

结果

垂直边缘差异的平均±标准偏差值对于PVS组为106±87μm，对于PVS A组为34±49μm，对于TRIOS 3组为53±56μm，对于CS 3600组为93±69μm 。在PVS组和TRIOS 3组之间以及CS 3600组和TRIOS 3组之间发现统计学上的显着差异（P <.05）。

结论

使用TRIOS 3进行的数字扫描显示的边际差异值低于使用CS 3600进行的数字扫描和使用弹性体进行的传统压印。