PDF(Pubmed)
Abstract：
Objectives: Some small defects may remain in the impression after making a two-step putty-light body impression. The aim of this study was to evaluate and compare the dimensional accuracy of 2-step and relined 2-step (3-step) putty-light body impressions. Materials and Methods: In this in vitro study, 30 impressions were made with putty, light body, and extra-light body addition silicone materials using the 2-step and 3-step impression techniques (N=15). An epoxy resin master model was made duplicating a maxillary typodont with left first premolar and first molar teeth prepared with a shoulder finish line and truncated pyramidal-shaped indices in the mid-palate and third molar sites. In addition to creating a reference digital model by scanning the master model, 30 master casts were scanned to produce digital models. The anteroposterior (AP) and cross-sectional (CS) dimensional accuracy of the models were compared with the master model using linear measurements. Moreover, tooth size measurements were made and compared using the root mean square (RMS). Two-sample t-test was applied to analyze the data (α=0.05). Results: The mean AP and RMS differences between the two study groups were not significant (P>0.05). However, the CS difference between the two groups was significant (P<0.001), and the 3-step impression technique showed smaller discrepancies in comparison to the master model. Conclusion: There was no significant difference in accuracy of the two techniques for single-unit and multiple-unit preparations. The 3-step impression technique had a higher CS dimensional accuracy.
摘要：
目的：制作两步腻子-轻体印模后，印模中可能会残留一些小缺陷。这项研究的目的是评估和比较2步和相关的2步（3步）腻子轻体印象的尺寸精度。材料和方法：在这项体外研究中，30个印象是用腻子做的，轻体,和使用2步和3步印模技术的超轻体添加有机硅材料（N=15）。制作了环氧树脂母模，复制了上颌字体，左第一前磨牙和第一磨牙的牙齿，并在the中和第三磨牙部位准备了肩终点线和截短的金字塔形指数。除了通过扫描主模型来创建参考数字模型之外，扫描了30个主模型以产生数字模型。使用线性测量将模型的前后（AP）和横截面（CS）尺寸精度与主模型进行了比较。此外，进行牙齿大小测量,并使用均方根(RMS)进行比较.数据采用双样本t检验(α=0.05)。结果:两组间AP和RMS平均值差异无统计学意义(P>0.05)。然而,两组之间的CS差异有统计学意义（P<0.001），与主模型相比，三步印象技术显示出更小的差异。结论：单单位和多单位制剂两种技术的准确性没有显着差异。3步印模技术具有较高的CS尺寸精度。
