Comprehensive Evaluation of Trueness and Precision in Extraoral Scanning Methods Using a 3D-Printed Human Head Model: An In Vitro Study

Objective: This in vitro study aimed to evaluate the accuracy of extraoral facial scanning methods using a 3D-printed human head model. Materials and Methods: A 3D-printed resin human head model was fabricated with 16 anatomical landmarks and 17 inter-landmark linear distances. These distances were measured using both a digital vernier caliper and Blender software (v4.5.2, Amsterdam, The Netherlands). Each measurement was repeated 10 times with the caliper and 15 times for each scanning system.Four scanning systems were compared: a handheld scanner (Metismile, Shining 3D, China), a desktop scanner (RAYFace v2.0, Ray Co., Korea), and two mobile scanning applications—Heges and Polycam (iPhone 15, Apple Inc., USA). The inter-landmark distances obtained from each scanner were compared with the reference caliper measurements. Trueness was analyzed using the Friedman test, while precision was assessed using the One-Way ANOVA test, followed by a post-hoc multiple comparison test to determine significant differences between groups when P values were below 0. 05. Results: Data analysis showed that the Polycam application exhibited the highest trueness (0.49 ± 0.32 mm), while the handheld scanner achieved the highest precision (0.12 ± 0.07 mm). The desktop RAYFace scanner demonstrated a precision of 0.28 ± 0.19 mm and trueness of 0.58 ± 0.39 mm, whereas the Heges application yielded a precision of 0.41 ± 0.17 mm and trueness of 0.73 ± 0.42 mm. The FRIEDMAN TEST test comparing trueness among RAYFace, MetiSmile, and Polycam yielded a p-value of 0.076> 0.05), indicating no statistically significant difference in trueness among the three systems. And there is no significant difference between 5 regions using Anova One-way Test with P>0. 05. All systems showed higher accuracy in vertical measurements than in horizontal ones. In the lower facial region, all 3D face-scanning systems demonstrated superior repeatability. Conclusions: The handheld scanner demonstrated the highest precision, whereas the Polycam application achieved the highest trueness. The desktop scanner exhibited greater precision than Polycam but lower than Heges, while its trueness was comparatively inferior. Clinical Significance: All four 3D facial scanning systems—including handheld, desktop, and mobile-based methods demonstrated clinically acceptable accuracy levels (< 0.6 mm) and can be effectively integrated with intraoral scanning and CBCT data within digital dental workflows. All systems in this study exhibited superior repeatability in the lower facial region compared with conventional anthropometric measurements, supporting their potential use for virtual patient creation and facially driven digital dentistry.