Trueness and precision of smartphone-based 3D scan in the assessment of facial edema in orthognathic surgery

Background: Although smartphone-based 3D facial scanning represents a low-cost tool for evaluating edema in maxillofacial surgery, evidence regarding its accuracy for clinical applications remains scarce. This study aimed to evaluate the trueness and precision of Qlone3D Scanner for smartphone in assessing postoperative edema following orthognathic surgery. Methods: This is a trueness and precision study. 3D facial reconstruction of computed tomography (CT) scans served as standard-reference. Both 3D facial models were converted to.STL format and imported to CloudCompare 2.14 for comparative mesh-to-mesh analysis. Trueness was defined by the proximity of smartphone-based scans to CT scans, while precision was assessed through comparison of subsequent smartphone-based scans. Statistical analysis was performed with SPSS 20.0. Results: Twenty-one participants were included. Trueness analysis showed similar average distance between mesh points in both preoperative (2.03 ± 0.74 mm) and postoperative (2.00 ± 0.68 mm). Precision analysis showed variability in the average distance between mesh points, with a mean of 2.97 ± 3.15 mm in preoperative period and of 1.89 ± 1.51 mm in postoperative period. No statistically significant differences were observed between preoperative and postoperative trueness or precision measurements (p > 0.05). The lower third of the face exhibited the greatest areas of divergence between mesh points. Conclusion: Postoperative facial edema did not significantly affect the trueness or precision of the Qlone3D Scanner. However, limitations in accurate surface reproduction were identified, restricting its applicability primarily to edema monitoring and underscoring the need for further refinement to ensure reliable clinical and research use.