Motion capture driven analytical modeling of temporomandibular joint kinematics in healthy and temporomandibular disorder subjects.

BACKGROUND

Quantitative assessment of temporomandibular joint kinematics may provide objective insight into altered mandibular motion in subjects with temporomandibular disorders; however, motion capture-driven analytical studies incorporating higher-order kinematic descriptors remain limited.

OBJECTIVE

To develop and evaluate a motion capture-driven analytical framework assessing displacement, velocity, acceleration, jerk, and movement smoothness during mouth opening-closing in asymptomatic and temporomandibular disorder subjects.

METHODS

Three representative subjects were analysed: one asymptomatic subject, one Class II malocclusion subject with mild disc displacement, and one Class II malocclusion subject with moderate disc displacement. Mandibular motion was recorded using an eight-camera Vicon optical motion capture system at 200 Hz. Condylar trajectories were reconstructed indirectly from mandibular rigid-body motion using anatomical condylar reference points. Coordinate data were processed in MATLAB to generate displacement-, velocity-, acceleration-, and jerk-time profiles. A Normalized Jerk Index quantified movement smoothness.

RESULTS

The asymptomatic subject showed biphasic mandibular motion, with initial rotation followed by combined rotation-translation, smooth kinematic profiles, and low jerk values. Mild disc displacement showed partially preserved opening-closing motion with reduced rotation, lateral deviation, localized velocity and acceleration peaks, and increased jerk responses. Moderate disc displacement showed restricted opening, reduced rotational-translational movement, asymmetric condylar pathways, abrupt acceleration changes, and high jerk discontinuities. Normalized Jerk Index increased from 1.77 in the asymptomatic subject to 3.49 and 6.91 in mild and moderate disc displacement, respectively.

CONCLUSION

This feasibility study demonstrated that this framework objectively characterizes temporomandibular joint motion. Higher-order kinematic descriptors provide information beyond displacement analysis, supporting validation in larger disorder cohorts.