Vibration analysis of the temporomandibular joints with degenerative joint disease.

The surface vibrations of 42 temporomandibular joints (TMJ) with degenerative joint disease (DJD) and/or perforation of the disk were evaluated using electrovibratography and compared to the surface vibrations of 83 joints with normal TMJ imagings and 61 joints with meniscal displacement without reduction. Through the frequency spectrum analysis, TMJs with DJD showed higher vibration energy above 350-450 Hz and TMJs with perforation showed higher vibration energy between 100-150 and 300-450 Hz. The presence of perforation did not seem to affect the characteristic of vibrations when TMJs were associated with DJD. A threshold was set for the total vibration energy as described in our previous report and used as a parameter in order to separate patients with internal derangement from a pool of TMJ dysfunction patients (diagnostic specificity = 75%, diagnostic sensitivity = 80.2%). Using this criteria, the following were correctly identified as internal derangement and/or DJD: a) 100% of the TMJs with meniscal displacement without reduction associated with DJD; b) 87.0% of the TMJs with meniscal displacement without reduction associated with perforation; c) 88.9% of the TMJs with meniscal displacement without reduction associated with DJD and perforation; and d) 100% of the TMJs with perforation.