Mandibular Kinematics on an Orthodontic Population Assessed with an Optical Jaw Tracking System: A Comparative Study

To evaluate mandibular kinematics in an orthodontic population using the Modjaw^® optical jaw tracking system.  A total of 154 orthodontic patients underwent mandibular kinematic analysis using the Modjaw^® system. ANB values determined skeletal classification, while dental classification was assessed on digital casts. The Modjaw^® records were taken as instructed by the manufacturer, and data collected from the readings included the discrepancy between centric occlusion and maximum intercuspation, maximum opening, Bennett angles, and sagittal condylar guidance. The presence or absence of temporomandibular disorders was determined by the DC-TMD questionnaires. Non-parametric tests and Spearman correlations were applied for the statistical analysis.  Significant differences in mandibular kinematics were observed between skeletal classes, particularly in CO-MI discrepancies, Bennett angles, and maximum opening (p < 0.05). TMD symptoms were associated with higher absolute CO-MI discrepancies but did not significantly alter other kinematic parameters. Weak correlations were found between sagittal condylar guidance and anterior guidance variables. Mandibular kinematics differ by skeletal classification, with Class III patients demonstrating distinct patterns. While TMD symptoms impact CO-MI discrepancies, overall mandibular dynamics remain consistent.