Reproducibility of temporomandibular joint clicking

To investigate the stability of temporomandibular joint (TMJ) clicking over a 10-day period and the effect of different open/close velocities on sound amplitude and power spectra in a group of subjects with subjectively stable unilateral clicking during the 3 months preceding the recordings.

Ten volunteers were recorded with a self-developed microcomputer-based system used in a previous study on asymptomatic subjects. The recordings were performed during 4 different sessions at 3 different open/close rates in each session. The subjective sound intensity was measured with a 100-mm visual analog scale (VAS). The VAS scores, the maximum amplitudes, and the power spectra of the signals were tested for statistical differences among the different open/close rates and over the sessions. The reliability of measurements was also calculated.

The maximum amplitude and the power spectra of the TMJ clicking varied between subjects in a broad range that differed from those reported for asymptomatic subjects. No statistically significant differences were found within subjects for the subjective VAS scores for the maximum signal amplitudes or for the power spectrum parameters among the open/close rates and over the 4 sessions. For all 3 open/close rates and for the 4 sessions, a good to excellent reliability of measurements was determined, the values of r being mostly over 0.75.

Within the limits of the experiment, TMJ clicking was subjectively and objectively stable over a period of 10 days. Therefore, the constant subjective perception of sound intensity was supported by the objective measurements.