Comparison of the Accuracy of Two Intraoral Scanners With Different Scanning Principles and Scanning Strategies: An in Vitro Study

Aim: To compare the accuracy (trueness and precision) of two intraoral scanners (IOSs) based on different scanning principles—triangulation and confocal imaging—using three different scanning strategies for completely edentulous maxillary arches. Materials and Methods: An in vitro study was conducted using a maxillary edentulous resin model. A reference scan was obtained with a laboratory scanner. Five conventional polyvinyl siloxane (PVS) impressions were made and digitized. Two IOSs—Shining 3D (triangulation) and TRIOS 3 (confocal)—were used to scan the model five times with each of three scanning strategies (A, B, C), resulting in 30 digital scans. All scans were aligned to the reference using a best-fit algorithm, and root mean square (RMS) deviation values were calculated for trueness and precision. Statistical analysis included Shapiro–Wilk and Levene’s tests, followed by ANOVA with Tukey’s HSD post hoc test (p < 0.05). Results: Scanner type significantly affected trueness (p = 0.004) and precision (p = 0.001). Conventional impressions demonstrated the highest trueness (mean RMS 0.142 µm), followed by TRIOS 3 (0.284 µm), while Shining 3D showed the lowest trueness (1.53 µm). Scanning strategy also influenced accuracy, with Strategy B yielding the best overall trueness (0.701 µm) and Strategy C producing the highest deviation (1.17 µm). A significant interaction effect between scanner type and scanning strategy was observed. Strategy B demonstrated greater accuracy when using the Shining 3D scanner, In contrast, with the TRIOS 3 scanner strategies A and C showed comparable results Conclusion: Both scanner type and scanning strategy significantly influence the accuracy of digital scans of edentulous maxillary arches. The TRIOS 3 scanner (confocal) demonstrated accuracy comparable to conventional impressions and superior to the Shining 3D (triangulation) scanner. Strategy B provided the highest accuracy overall, emphasizing the importance of proper scanning pathway selection to optimize digital denture fabrication.