Association Between TMJ Sounds And Lateral Mandibular Deviations In Patients With Disc Displacement

Temporornandibular joint(TMJ) sounds is one of important signs and symptoms in temporomandibular disorders(TMD) pathologic changes. TMJ sounds are also important basis for classifications diagnostic in TMD patients. Characteristics of TMJ sounds’ spectrum are associated with articular disc displacement during jaw’s functional movement. Therefore, analysis of TMJ sounds, mandibular movement and electromyography, may clarify biological and pathological mechanisms of TMD.Objective:The aim was to study the characteristics of lateral mandibular deviations and their association with TMJ sounds and EMG activity during TMD patient jaw opening-closing movements. Method:Subjects were22healthy controls and28patients diagnosed as TMJ disc dysfunction by MRI imaging,14with disk displacement without reduction (DD) and14as disc displacement with reduction (DDR). Software was written for synchronization two data recording systems, one recorded TMJ sounds with miniature microphones which placed in ear canals, sampling rate48kHz. The other recorded EMG, jaw movements and TMJ vibrations with sampled rate at4kHz. Sudden changing of the direction of the mandibular deviation is labeled as mandibular unbalanced lateral deviation Take maximum displacement of the lateral deviation within the groups as the comparison.Results:The results showed that short-rapid velocity and direction changes which defined as unbalanced deviations from a smooth path in the horizontal plane, were associated with TMJ sounds of clicking type and occurred significantly more often in patients with DDR (p<0.001) than that of control and DD group. Frequency of Unbalanced deviations was no difference between controls and DD patients, nor deviation differences at degrees(mm) between controls and patients. Conclusion:Characteristics of TMJ sounds are associated with unbalanced lateral mandibular deviation; Electronic recording of lateral jaw movements, TMJ sounds and EMG can be as an objective data of diagnostic value in TMD patient.