Investigating the effect of scan speed on the full-arch accuracy of an intra-oral scanner- An in-vitro study

Abstract

Purpose: This in vitro study aimed to assess whether different scanning speeds affect the trueness and precision of the full-arch digital impression. Methods: A fully dentate unprepared mandibular model (Dental Model ANA-4, Frasaco GmbH, Tettnang, Germany) was scanned using the intraoral scanner CEREC Omnicam (Sirona–Dentsply, Bensheim, Germany, Software CEREC SW 5.0). The full-arch model was scanned ten times at a slow speed, ten times at normal speed, and ten times at fast speed by the same operator. Thus, the number of total scans was 30 scans. Three key points were manually identified on the first scan of each scan group, and then all scans of each speed were aligned to the first scan of the group to evaluate each scanning speed's precision. The same model was scanned with two high-resolution reference scanners: inEos X5 (Sirona–Dentsply, Bensheim, Germany), and 3Shape D2000 (3 Shape, Copenhagen, Denmark) to compare the trueness of each speed scanned by the CEREC Omnicam. The same key points were identified in these two reference scanners and the linear distance measured to evaluate each speed's trueness. The Bartlett's test for Homogeneity of Multi-variances was used to assess the precision, and one-way ANOVA and unpaired t-tests were used to compare the trueness across the three scan speeds. Results: No significant difference was found in the trueness and the precision of full-arch scans using different scanning speeds for a CEREC Omnicam intraoral scanner (IOS). The trueness of the inter-molar distance showed errors of 0.5mm and more in all cases. Conclusions: Accuracy of the IOS scan did not differ using different scanning speeds. The inter-molar distance was responsible for most of the cross arch error, and was clinically unacceptable. Therefore, quadrant dentistry would be a better choice to use with the CEREC Omnicam IOS.