Bias Evaluation of the Accuracy of Two Extraoral Scanners and an Intraoral Scanner Based on ADA Standards

Abstract

The spread and application of computer-aided design/computer-aided manufacturing (CAD/CAM) technology have contributed to the rapid development of digitalization in dentistry. The accuracy of scan results is closely related to the devising subsequent treatment plans and outcomes. Professional standards for evaluating scanners are specified in the American National Standard/American Dental Association Standard 132 (ANSI/ADA No. 132). The aims of this study were to use the three samples mentioned in ANSI/ADA No. 132 and evaluate the accuracy and reproducibility of two extraoral scanners and an intraoral scanner based on the inspection standards recommended by ANSI/ADA No. 132. In this study, two trained operators used two extraoral scanners (E4, 3Shape, Denmark & SHINING DS100+, Shining, China) and an intraoral scanner (TRIOS SERIES3, 3Shape, Denmark) to perform 30 scans of each of the three samples at a temperature of 25 ± 2 ° C and export standard tessellation language files and used reverse engineering software to perform measurements and iterative nearest point matching experiments. The measured values obtained were compared with the reference values measured by a coordinate measuring machine (NC8107, Leader Metrology, USA). We performed a normal distribution test (Shapiro-Wilk test), the nonparametric Kruskal-Wallis test, and an independent-samples t -test to analyze the reproducibility of each scan for different models. The experimental results indicate that the trueness and precision of the two extraoral scanners and the intraoral scanner had a slight mean deviation. The trueness and precision of the three scanners on the curved surface and groove areas are poor. The accuracy and reproducibility of E4 outperformed SHINING and TRIOS. The iterative closest point matching experiment also showed good matching results. The two extraoral scanners and the intraoral scanner in this study can meet the basic clinical requirements in terms of accuracy, and we hope that digital technology will be more widely used in dentistry in the future.

Accuracy of different laboratory scanners for scanning of implant‐supported full arch fixed prosthesis

“…20,21,12,22,23 Laboratory scanners will process either the impression or the stone cast of the dental arch and are able to digitally build an object based on the data obtained in the 3D point coordinate system. 24,25 The disadvantages of LS include impression materials dimensional changes and resulting stone cast, impression material displacement from the special tray, disinfection of impression and patient discomfort when the impression must be repeated. 12,26,27,28 However, LS is significantly more precise than intraoral scanners in cross-arch scans.…”

An overview of three‐dimensional imaging devices in dentistry

“…In recent years, there has been rapid development of 3D scanning and imaging technologies, which are now commonly utilized in the visualization and reconstruction of human anatomical structures, such as orthotics and prosthetics 89 . The correct formulation of subsequent treatment plans is dependent on the accuracy of the scans; therefore, performance evaluation of scanning and imaging devices is becoming increasingly important 90 …”

“…In these studies, the measurements, validation process, and artifacts in the evaluation processes were taken into consideration and realized in compliance with the guidelines VDI/VDE 2634 for optical 3D measuring systems, UNI EN ISO 12836:2015, 97 ISO/WD 5725:1994, 98 ANSI/ADA Standard No. 132–2015, 99 among other 40,90,100 . Accuracy includes trueness and precision 98 .…”

“…Sophisticated measuring instruments (such as Vernier calipers) are typically used to obtain measurements from the master model 40 . Some studies further optimized the experiment using a measuring instrument with extremely high accuracy (such as a coordinate measuring machine) to obtain measurements from the master model to be used as the gold standard 90,101 . The accuracy of the scanner was obtained by statistical analysis of the data of the master and virtual models.…”

“…The average values of the authenticity and accuracy of the traditional impression are lower than those of the oral scanner, which are 22.5 respectively μm and 13.5 μm. In several studies, researchers have evaluated the accuracy of scanners by combining the methods of distance measurement and image fitting 29,90 . The advantage of this method is its ability to quantitatively analyze the data and visualize the comparison results using a color map.…”