Accuracy of Automatic vs Point-based Semiautomatic Registration for Superimposition of Digital Dental Cast to Cone Beam Computed Tomography Three-dimensional Image in Computer-guided Prosthodontic Planning: A Cross-sectional Study

Purpose: The purpose of this study was to compare the accuracy of the automatic registration of digital dental casts to cone beam computed tomography (CBCT) images vs the point-based semiautomatic registration. Materials and methods: Twenty single jaws of partially edentulous patients were included. For each patient, a CBCT scan was performed, and a dental stone cast was scanned using a desktop scanner. The acquired digital data were imported into Blue-Sky-Plan software. Image registration was performed twice: the first was the automatic registration, while the second was the point-based semiautomatic registration. For accuracy assessment, three digital surface images were exported from Blue-Sky-Plan software and then imported with the same orientation into Medit Design software. The square root of the mean square of the distance measurements [root mean square (RMS)] was used to measure the deviation between the CBCT surface and the registered cast by each technique, and also between the cast alignments in the two registration techniques. A color map was used to visually assess the error distribution. Comparison between the deviation errors in both registration techniques was analyzed using the paired <i>t</i>-test, while inter- and intraobserver reliability were analyzed using the intraclass correlation coefficient (ICC). Results: The RMS error was 0.33 mm for automatic registration and 0.32 mm for point-based registration, with no statistically significant difference (<i>p</i> < 0.05) between the two methods. For the deviation between the cast alignment of the two different registration techniques, the RMS error was 0.11 mm. Both registration techniques showed strong inter- and intraobserver agreement (<i>p</i> < 0.05). Conclusion: The automatic registration of the digital cast image to the CBCT scan using Blue-Sky-Plan software is as accurate and reliable as the point-based semiautomatic registration technique. The automatic registration technique can be used to decrease planning steps, save planning time, and eliminate operator-related discrepancies. Clinical trial registration number: ORAD 6-3-1 (www.clinicaltrials.gov). How to cite this article: Mostafa NS, Anter E, Abd Alsamad AM. Accuracy of Automatic vs Point-based Semiautomatic Registration for Superimposition of Digital Dental Cast to Cone Beam Computed Tomography Three-dimensional Image in Computer-guided Prosthodontic Planning: An Observational Study. Int J Prosthodont Restor Dent 2024;14(4):225–233.