Comparison of the accuracy of complete-arch scans obtained using different scanning strategies and intraoral scanners on a paediatric typodont model: an in vitro study

With the growing integration of digital workflows in paediatric dentistry, intraoral scanners (IOS) are increasingly preferred over traditional impression methods because of their improved patient comfort and clinical efficiency. However, limited research exists on the accuracy of different scanning strategies tailored to paediatric cases. This in vitro study aimed to evaluate the accuracy (trueness and precision) of intraoral scans obtained via two IOS devices with different technologies and four distinct scanning strategies. Eighty intraoral scans were acquired from a paediatric typodont model (PedoPrep Jaw Model, EduDent, Istanbul, Turkey) using two IOS devices with different acquisition technologies: Helios 600, based on structured light technology (Eighteeth, Changzhou, China), and Trios 5, based on confocal microscopy technology (3Shape, Copenhagen, Denmark). Four scanning strategies (S1–S4), including manufacturer-recommended and experimental protocols, were implemented, with 12-minute intervals between scans to standardize acquisitions. Reference scans were captured using a desktop scanner (Ceramill Map 400, Amann Girrbach GmbH, Pforzheim, Germany). All data were processed in STL format and analysed using GOM Inspect 2018 software (GOM GmbH, Braunschweig, Germany). Accuracy was assessed via three-dimensional (3D) superimposition, calculating RMS deviations for trueness and precision. Two-way ANOVA (IOS device × scanning strategy) was performed separately for each dental arch, followed by Tukey post hoc tests ( p < 0.05). Trueness values ranged from 9.7 to 12.1 μm (maxilla) and 9–11.2 μm (mandible), whereas precision values ranged from 23.2 to 25.5 μm and 23.1–25.2 μm, respectively. The highest accuracy was observed with the S2 (quadrant-based) strategy for both IOS. The Helios 600 scanner showed significantly reduced accuracy in the S3 (zigzag) strategy compared with the other strategies ( p < 0.05), whereas Trios 5 maintained consistent performance across strategies. Statistically significant differences between the IOS were identified for S3 in both jaws, favouring Trios 5. The scanning strategy significantly influenced the accuracy of intraoral scans in paediatric models. Noncontinuous, quadrant-based strategies (S2) outperformed continuous or zigzag patterns (S3), particularly when using the structured-light IOS. In contrast, the confocal microscopy-based IOS demonstrated more consistent performance across different scanning strategies. These findings suggest that both the scanning strategy and IOS acquisition technology should be considered when developing paediatric-specific scanning protocols to improve the quality of complete-arch intraoral scans in clinical practice.