In Vivo Accuracy Assessment of Two Intraoral Scanners Using Open-Source Software: A Comparative Full-Arch Pilot Study

Background: The precision of intraoral scanners (IOSs) is a key factor in ensuring the reliability of digital impressions, particularly in full-arch workflows. Although proprietary metrology tools are generally employed for scanner validation, open-source platforms could provide a cost-effective alternative for clinical research. Methods: This in vivo study compared the precision of two IOSs—3Shape TRIOS 3 and Planmeca Emerald S—using an open-source analytical workflow based on Autodesk Meshmixer and CloudCompare. A single healthy subject underwent five consecutive full-arch scans per device. Digital models were trimmed, aligned by manual landmarking and iterative closest-point refinement, and analyzed at six deviation thresholds (<0.01 mm to <0.4 mm). The percentage of surface points within clinically acceptable limits (<0.3 mm) was compared using paired t-tests. Results: TRIOS 3 exhibited significantly higher repeatability than Planmeca Emerald S (p < 0.001). At the <0.3 mm threshold, 99.3% ± 0.4% of points were within tolerance for TRIOS 3 versus 92.9% ± 6.8% for Planmeca. At the <0.1 mm threshold, values were 89.6% ± 5.7% and 47.3% ± 13.7%, respectively. Colorimetric deviation maps confirmed greater spatial consistency of TRIOS 3, particularly in posterior regions. Conclusions: Both scanners achieved clinically acceptable precision for full-arch impressions; however, TRIOS 3 demonstrated superior repeatability and lower variability. The proposed open-source workflow proved feasible and reliable, offering an accessible and reproducible method for IOS performance assessment in clinical settings.