Comparison of accuracy of three intraoral scanners for different types of tooth preparations: A laboratory study.

Purpose: To evaluate the laboratory accuracy of three intraoral scanners (IOSs) across three types of tooth preparations, using a laboratory scanner as the reference.

Methods: Models of three types of tooth preparations (inlay, onlay, and three-unit fixed partial denture) were designed with CAD software and fabricated using a 3D printer. Reference data were obtained by scanning these models with a desktop laser scanner (Identica Hybrid, Medit Co). Each model was scanned five times using three IOSs: TRIOS4 (3Shape), I500 (Medit Co), and COMFORT+ (DDS), resulting in 45 scans across nine groups. Scan files were exported in STL format and analyzed with Geomagic 3D inspection software. Accuracy was assessed using best-fit alignment and 3D comparison functions.

Results: Trueness did not significantly differ among the IOSs within each tooth preparation group (P> 0.05). However, all three IOSs showed significantly lower trueness for the three-unit fixed partial denture compared to the inlay and onlay groups (P< 0.05). Precision significantly varied among the IOSs within the tooth preparation groups (P< 0.05). Specifically, the I500 demonstrated higher precision for inlays, while TRIOS4 and I500 exhibited better precision for onlays and three-unit fixed partial dentures.

Clinical Significance: All three tested intraoral scanners (TRIOS, I500, and COMFORT+) demonstrated clinically acceptable accuracy for prostheses fabrication, confirming their suitability for applications ranging from inlays to crowns and bridges.