Accuracy of Motion Trajectory Achieved with an Intraoral Scanner: An In Vitro Study with a Proof-of-Concept

Background: With the advancement of digital technology, it has become possible to record jaw motion using intraoral scanners. However, there is a paucity of studies evaluating their accuracy. Methods: Twelve sets of scan data from 12 individuals were additively manufactured using a 3D printer and 3D-printable material. Each pair of scan data was mounted onto a semi-adjustable articulator. A blue articulating paper was inserted between the mounted models, and the pin of the articulator was moved to simulate motion (ART group). Subsequently, intraoral scan data were obtained, and the movements of the articulator were recorded. The trajectory expressed in the intraoral scanner software (TRIOS3; 3Shape A/S, Copenhagen, Denmark) appeared red on the monitor screen (IOS group). The blue and red areas in the ART and IOS groups, respectively, were measured in pixels for each tooth type, and the number of trajectories marked or expressed for each tooth type was counted. Results: Regarding the areas of trajectory, significant differences were observed between the ART and IOS groups across all tooth types. Statistically significant differences were also noted in the number of trajectories for the first premolars and first molars between the two groups. Conclusions: Intraoral scanners may not accurately reproduce motion movements at the current level of technology. However, these results should be interpreted with caution because defining the trajectory accuracy between the two groups is challenging unless the (two) trajectories are exactly the same.