Statement of problem

Information on the morphological accuracy of crowns produced by different technologies is limited.

Purpose

The purpose of this in vitro study was to compare the morphology and contacts of crowns fabricated with intraoral systems, extraoral systems, and conventional method.

Material and methods

A typodont mandibular first molar (Nissin Dental Product) received a complete ceramic crown preparation and a reference crown. Microcomputed tomography (μCT) was used to obtain the virtual data (REF) of the reference crown. Three groups of replicated crowns were made: intraoral scanning system (TRIOS), extraoral scanning system (D700), and the conventional method (CONV) (n=8). The groups TRIOS and D700 were designed by the correlation method. All crowns were scanned with μCT to obtain 3D data. The data were superimposed on each other or the REF in an inspection software to evaluate precision and trueness. The contact penetration area of the occlusal surfaces of the crowns was calculated. An independent sample t test and 1-way ANOVA with the post hoc least significant difference (LSD) test were used to compare the data (α=.05).

Results

The crowns fabricated with the extraoral scanners showed significantly lower root mean square (RMS) values for trueness (F=1456.90, df=2, P<.001) and precision (F=188.88, df=2, P<.001) than the others. The penetration contact area ratio and the differences in the CONV group were both significantly higher than those of the other groups.

Conclusions

The average discrepancies of the crown morphology fabricated from the extraoral scanning were significantly lower than those from others. The conventional method restored the occlusal contact with significantly less accuracy than the other groups.

中文翻译：

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不同技术制造的牙冠形态准确性的比较评估

问题陈述

有关通过不同技术生产的牙冠的形态准确性的信息有限。

目的

这项体外研究的目的是比较用口腔内系统，口腔外系统和常规方法制成的牙冠的形态和接触。

材料与方法

牙突下颌第一磨牙（Nissin牙科产品）接受了完整的陶瓷牙冠制备和参考牙冠。使用微计算机断层扫描（μCT）获得参考牙冠的虚拟数据（REF）。制成三组复制的冠：口内扫描系统（TRIOS），口外扫描系统（D700）和常规方法（CONV）（n = 8）。TRIOS和D700组是通过相关方法设计的。用μCT扫描所有牙冠以获得3D数据。数据相互叠加或在检查软件中的REF上叠加以评估精度和真实性。计算出牙冠的咬合面的接触穿透面积。独立样本t 检验和事后最小显着性检验（LSD）的1-way ANOVA用于比较数据（α= .05）。

结果

用口外扫描仪制作的牙冠的真实度（F = 1456.90，df = 2，P <.001）和精度（F = 188.88，df = 2，P <.001）的均方根（RMS）值均显着降低其他。CONV组的穿透接触面积比和差异均显着高于其他组。

结论

口腔外扫描形成的冠状形态平均差异显着低于其他形态。常规方法恢复咬合接触的准确性明显低于其他组。