Statement of problem

The accuracy of intraoral and extraoral scanners for different models of edentulousness is unclear.

Purpose

The purpose of this in vitro evaluation was to determine the accuracy (trueness and precision) of complete-arch scans made by 3 intraoral and 1 extraoral scanners compared with an industrial 3D scanner.

Material and methods

Digital scans were made of a reference cast with 3 intraoral scanners (CEREC Omnicam; Dentsply Sirona, TRIOS 3; 3shape A/S; Carestream CS 3600; Carestream Dental) and an extraoral scanner (Deluxe scanner; Open Technologies). A dental maxilla model was used for tooth preparation for ceramic restorations with a shoulder finishing line. Maxillary right central and lateral incisors and third molar and maxillary left second premolar and first and third molar teeth were removed. One operator scanned the reference cast 10 times with each scanner. All the recorded standard tessellation language (STL) files were imported into an inspection software program and individually overlaid on the STL file for the reference model made by the 3D scanner. The measured distance between the distal point of the maxillary left second molar tooth and the mesial point of the maxillary left first premolar was defined as distance 1; distance 2 was defined as the distance between the mesial point of the maxillary second molar tooth and the distal point of the maxillary right first premolar tooth. The Levene test for homoscedasticity of variances was used to evaluate precision, and a 2-way repeated-measures ANOVA and Bonferroni-corrected Student t tests were used to evaluate trueness (α=.05).

Results

A statistically significant difference was found between the Carestream scanner and the other scanners when scanning both mucosa and teeth. The Carestream scanner had the lowest accuracy and highest magnitude mean deviation of all the scanners.

Conclusions

Obtaining an accurate partial-arch impression is still challenging for some intraoral scanners. The Carestream scanner’s trueness was outside the acceptable range. However, other scanners tested here appeared to be suitable alternatives to conventional impression techniques.

中文翻译：

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口内和口外完整牙弓扫描准确性和精密度的体外评估

问题陈述

口内和口外扫描仪对不同缺牙模型的准确性尚不清楚。

目的

此体外评估的目的是确定由 3 台口内和 1 台口外扫描仪与工业 3D 扫描仪进行的完整牙弓扫描的准确性（真实性和精确度）。

材料与方法

数字扫描由带有 3 台口内扫描仪（CEREC Omnicam；Dentsply Sirona，TRIOS 3；3shape A/S；Carestream CS 3600；Carestream Dental）和口外扫描仪（豪华扫描仪；Open Technologies）的参考模型组成。牙齿上颌模型用于具有肩部精加工线的陶瓷修复体的牙齿制备。上颌右侧中切牙和侧切牙以及第三磨牙和上颌左侧第二前磨牙和第一和第三磨牙牙齿被移除。一名操作员用每台扫描仪扫描参考模型 10 次。所有记录的标准曲面细分语言 (STL) 文件都被导入到检测软件程序中，并单独覆盖在 3D 扫描仪制作的参考模型的 STL 文件上。上颌左侧第二磨牙远中点与上颌左侧第一前磨牙近中点之间的测量距离定义为距离1；距离 2 定义为上颌第二磨牙近中点与上颌右侧第一前磨牙远中点之间的距离。方差同方差性的 Levene 检验用于评估精度，2 路重复测量方差分析和 Bonferroni 校正学生t检验用于评估真实性 (α=.05)。

结果

在扫描粘膜和牙齿时，Carestream 扫描仪与其他扫描仪之间存在统计学上的显着差异。Carestream 扫描仪在所有扫描仪中准确度最低，平均偏差幅度最大。

结论

对于一些口内扫描仪来说，获得准确的部分牙弓印模仍然具有挑战性。Carestream 扫描仪的真实度超出了可接受的范围。然而，这里测试的其他扫描仪似乎是传统印模技术的合适替代品。