Comparison of the reproducibility of maxillary position transfer with a mechanical facebow and those with facial scanning and cone beam computed tomography, based on a method of model orientation using anatomical landmarks

PURPOSE: This study introduced a method of model orientation and virtual articulator mounting using anatomical landmarks. This method aimed to establish a standardized reference framework for maxillary position transfer, which was evaluated through precision analysis against a mechanical facebow. MATERIALS AND METHODS: Twelve participants with intact dentition and symmetrical craniofacial morphology were recruited. Three workflows were compared: (1) indirect maxillary position transfer using a mechanical facebow (IT), (2) direct maxillary position transfer using facial scanning (DT1), and (3) direct maxillary position transfer using cone beam computed tomography (CBCT) (DT2). Each workflow was repeated five times per participant. The proposed method defined reference planes through anatomical landmarks to orientate integrated multimodal models and transfer the maxillary position to the reference framework. The precision of each transfer was quantified by measuring the average distance between repeated sample points and the three-dimensional (3D) root mean square deviation (RMSD) at the maxillary central incisor midpoint, maxillary right first molar, and maxillary left first molar. Spatial dispersion was analyzed using a 3D coordinate transformation matrix, decomposed into angular and linear displacements. Additionally, the spatial relationships among the three groups were compared using the coordinates of the maxillary central incisor midpoint and the occlusal plane angle. RESULTS: , respectively; p < 0.001). CONCLUSIONS: The DT techniques demonstrated superior precision compared to the IT technique, with the CBCT-based DT2 technique achieving the highest reproducibility. The proposed method of model orientation using anatomical landmarks improves both precision and efficiency compared to the traditional facebow method, and flexibility in choosing reference equivalents, without requiring additional equipment or chairside time. Thus, it provides a full digital reference framework for 3D model orientation and maxillary positioning.