Multiparameter Measurement System for Analyzing the Temporomandibular Joint Complex

The temporomandibular joint (TMJ) is one of the most complex joints in the human body, but its biomechanics has not been as extensively researched as other body joints, leading to a fundamental gap in understanding the physiological characteristics and diagnostics of related disorders. This work introduces a measurement system that applies a precise counterforce against mouth opening, enabling the study of jaw motion under both static and dynamic conditions. Unlike conventional methods, this system assesses mandibular function without solely relying on subjective, isotonic, or isometric techniques. The system simultaneously measures the degree of jaw opening, symmetry of jaw opening force, electromyography (EMG), and handgrip force as pain feedback. An exploratory study was conducted with five healthy participants, and their results were compared with those of a dysgnathia patient. In the healthy group, a maximum jaw opening force of ${161} \pm {58}$ N was recorded, approximately doubling the jaw opening forces previously discussed in literature. The dysgnathia patient showed a 39.8% reduction in maximum jaw opening force compared to a similar healthy participant and experienced moderate pain (4 on the NPRS-11 scale) at a jaw opening angle of 10°. These findings demonstrate the system’s capability to objectively assess multiple functional parameters simultaneously. This system bridges the gap in TMJ diagnostics and offers a comprehensive tool for evaluating mandibular function.