Comparative Analysis of Mandibular Kinematics Recorded with Zebris JMA and Medit i700 Using an Open-Source 3D...

Background/Objectives: Mandibular kinematics are increasingly central to the construction of the digital dental avatar, and can be recorded with two categories of devices: dedicated jaw motion analysers and intraoral scanners with motion-tracking modules. Few studies have compared these categories on the same patients. This pilot study compared the Zebris JMA and Medit i700 in a paired-cohort design, using an open-source Blender-based framework developed for the uniform analysis of their XML exports. Methods: A prospective, observational, paired-cohort study was conducted on 17 adults recorded with both systems by a single operator. A custom Python 3.11 add-on for Blender 4.5 LTS and Blender4Dental 1.1.99, developed within the study, supported the analytical workflow. A common anatomical origin between the two systems was first validated by comparing the occlusal contact area at MIP. At each threshold, the two systems were then compared on the directional decomposition (X, Y, Z components) of the mandibular displacement along the anatomical axes. Agreement was evaluated using paired t-tests or Wilcoxon signed-rank tests, Bland-Altman analysis, Pearson or Spearman correlation coefficients, and the intraclass correlation coefficient. Results: Validation at maximum intercuspation showed near-perfect agreement between the two workflows (Pearson r = 0.997; ICC(2,1) = 0.997). During protrusion, the dominant displacement component shifted to the anteroposterior axis. SVD residuals were smaller for Medit (~0.003-0.004 mm) than for Zebris (~0.024-0.046 mm; p < 0.001), but were interpreted only as internal rigid-body fitting residuals rather than accuracy metrics. Conclusions: Zebris JMA and Medit i700 yielded similar scalar displacement values under the threshold-based frame-selection procedure, but showed systematic differences in directional decomposition.