Relationship Between Angle Class I and Class II Dental Classification and Condylar Parameters Measured with a Digital Jaw Tracking System: A Cross-Sectional Study

Background and Objectives: The integration of digital jaw tracking systems into prosthodontic workflows has created new opportunities for individualized articulator programming. Sagittal condylar inclination (SCI) and Bennett angle (BA) are the key condylar guidance parameters required for this purpose, yet whether these values differ systematically across Angle dental classes remains debated. This study compared condylar guidance parameters recorded with a digital jaw tracking system between Angle Class I and Class II subjects, and assessed inter-session reliability and right-left symmetry of the recordings. Materials and Methods: In this prospective cross-sectional study of a convenience sample, 118 participants were included (109 Angle Class I; 9 Angle Class II; no Angle Class III participants were identified). SCI and BA were recorded with the Modjaw system (Modjaw, Villeurbanne, France) across three separate sessions during protrusion and lateral excursions of the mandible. Inter-session reliability was assessed using the intraclass correlation coefficient [ICC(3,1) and absolute-agreement ICC(A,1)] and the standard error of measurement (SEM); between-group differences with the Mann–Whitney U test; and right–left symmetry with the Wilcoxon signed-rank test (α = 0.05). Results: Inter-session relative reliability was high for all articular parameters (ICC(3,1) 0.953–0.991; ICC(A,1) 0.952–0.991; SEM 0.9–2.2°). No statistically significant differences in SCI or BA were identified between Class I and Class II subjects (all p > 0.05), although the Class II estimates were imprecise (e.g., right BA: Hodges–Lehmann estimate +4.67°, 95% CI −0.67° to +10.67°). Mean SCI in Class I ranged from 50.04° ± 9.56° to 54.05° ± 10.15°, and in Class II from 49.74° ± 13.80° to 53.04° ± 15.26°. No significant right–left asymmetry was found in either group (all p > 0.09). Conclusions: No statistically significant differences in SCI or BA were detected between the observed Angle Class I and Class II participants; however, the small and highly imbalanced Class II sample limits the precision of these estimates and does not allow conclusions regarding equivalence; no a priori sample-size calculation was performed, and only large differences (approximately 9–11° for SCI and 7–10° for BA) could have been detected. Modjaw recordings showed high inter-session relative reliability. Given the considerable inter-individual variability, patient-specific recording of condylar guidance appears preferable to estimation based on Angle class for articulator programming.