2026 年 4 巻 1 号 p. 1-10
Purpose : This study aimed to evaluate the dimensional accuracy of digital impressions and optical bite registrations obtained from two laboratories and six intraoral scanners using volumetric analysis and helical axis (HA) assessment.
Materials and Methods : A reference model with 12 embedded steel spheres was scanned using a high-precision coordinate measuring machine to obtain control data. The model was then scanned 10 times with each of the eight digital scanners. Sphere diameters and intra-dental sphere distances were analyzed using 3D analysis software. Occlusal relationships were assessed by measuring distances between extra-dental sphere pairs and calculating HA based on spatial transformations of the lower dentition relative to the upper.
Results : Laboratory scanners demonstrated greater trueness and precision in both sphere diameter and intra-arch measurements compared to intraoral scanners. Accuracy varied among intraoral scanners, likely owing to differences in scanning technologies. For interocclusal evaluations, intraoral scanners generally exhibited lower accuracy, with some instances of significant deviations from the reference data.
Conclusion : The accuracy of digital impressions and optical bite registrations varies significantly across scanners and is influenced by the scanning technology used. Laboratory scanners demonstrated greater accuracy than intraoral scanners in both dentition and occlusal relationship. In the context of optical bite registration, lab scanners may digitally calibrate errors via algorithms, whereas improving the accuracy of intraoral scanners will likely require advancements in hardware specifications. The HA method was effective in evaluating intermaxillary registration accuracy and may serve as a standard in future research.
