Abstract
The advancement of intraoral scanners has allowed for more efficient workflow in the dental clinical setting. However, limited data exist regarding the accuracy of the digital impressions produced with various scanner settings and scanning approaches. The purpose of this in vitro study was to compare the accuracy of digital impressions at the crown preparation margin using different scanning resolutions of a specific intraoral scanner system. An all-ceramic crown preparation of a mandibular first molar was constructed in a typodont, and a scan (n = 3) was created with an industrial-grade laboratory scanner (3Shape D2000) as the control. Digital impressions were obtained with an intraoral scanner (3Shape TRIOS 3) under three settings—high resolution (HR), standard resolution (SR), and combined resolution (SHR). Comparative 3D analysis of scans was performed with Geomagic Control X software to measure the discrepancy between intraoral scans and the control scan along the preparation finish line. The scan time and number of images captured per scan were recorded. Statistical analysis was performed by one-way ANOVA, two-way repeated measures ANOVA, Pearson’s correlation, and Dunnett’s T3 test (α = 0.05). Significant differences were observed for scan time and for number of images captured among scan resolution settings (α < 0.05). The scan time for the SR group was, on average, 34.2 s less than the SHR group and 46.5 s less than the HR group. For discrepancy on the finish line, no significant differences were observed among scanning resolutions (HR: 31.5 ± 5.5 μm, SHR: 33.2 ± 3.7 μm, SR: 33.6 ± 3.1 μm). Significant differences in discrepancy were observed among tooth surfaces, with the distal surface showing the highest discrepancies. In conclusion, the resolution of the intra-oral scanner is primarily defined by the system hardware and optimized for default scans. A software high-resolution mode that obtains more data over a longer time may not necessarily benefit the scan accuracy, while the tooth preparation and surface parameters do affect the accuracy.
Highlights
Computer-aided design and computer-aided manufacturing (CAD/CAM) technology has drastically changed the face of dentistry since it was introduced to the field in the 1980s [1]
The results of this study showed that the accuracy of the 3Shape TRIOS 3 scanner, regardless of scanning resolution, falls within clinically accepted limits and is comparable to previously published data that showed a discrepancy that ranged from 6.9 ± 0.9 μm to 119 ± 48 μm [4,9,16,17,18,19,20]
Significant differences in terms of scan time and number of images captured per scan were observed among the three groups with different scanning resolution settings
Summary
Computer-aided design and computer-aided manufacturing (CAD/CAM) technology has drastically changed the face of dentistry since it was introduced to the field in the 1980s [1]. In the early stages of the application of CAD/CAM to dentistry, desktop scanners were used in dental laboratories to digitize gypsum models before the milling and manufacturing of dental prosthetics [2]. The advancement of chairside CAD/CAM systems has provided a more efficient digital workflow in the clinical setting [3]. The use of intraoral scanners as an alternative to conventional impression reduces patient discomfort, is more environmentally friendly, and is easier for clinicians to manipulate without the risk of Sensors 2020, 20, 1157; doi:10.3390/s20041157 www.mdpi.com/journal/sensors. Other advantages of intraoral scanning include real-time visualization and magnification, color-scanning for esthetic shade selection, and better patient compliance
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