Impact of different scanning strategies on the accuracy of two current intraoral scanning systems in complete-arch impressions: an in vitro study

Aim: To determine the scanning strategy that obtains the most accurate results for two intraoral scanners (IOS) in complete-arch digital impressions. Scan time was evaluated and correlated with scan strategies. Materials and method: A custom model used as the reference standard was fabricated with teeth having dentin- and enamel-identical refractive indices simulating natural dentition. A reference scan of the custom typodont was obtained using an ATOS III Triple Scan 3D optical scanner. Two IOS setups - Omnicam v 5.1.0 and Primescan v 5.0.2 - were used for complete-arch scanning, each using 13 scanning strategies, obtaining 260 digital files (n = 10 per group), recording each scan time, converting all experimental scans to standard tessellation language (STL) format, and using a comprehensive metrology program to compare the reference standard scan with the experimental scans. Statistical analyses utilized Welch's unequal variances t test. Results: Group M exhibited the lowest trueness and precision values (P 0.05) for Primescan (47.5% of the average among all other groups) and the lowest trueness value (P 0.05) for Omnicam (53.4% of the average among all other groups), where group B exhibited the lowest precision value (65.6% of the average among all other groups) with P 0.05. Primescan featured a better trueness index (4.79 µm) than that of Omnicam (19.13 µm), with a statistically significant difference (P 0.00001). Primescan, group M, also featured a better precision index (4.67 µm) than Omnicam, group B (16.75 µm), with a statistically significant difference (P 0.00001). Conclusion: For both IOS systems, group M provided the lowest scanning times. For trueness and precision of complete-arch scans, group M was the dominant scanning strategy in Primescan, while there was no dominant strategy in Omnicam. Group M had the best scanning time for both IOS systems. Keywords: CAD/CAM, intraoral scanner, digital impression, accuracy, full-arch dental impression, standard tessellation language