Comparison of TMJ vibration frequencies under different joint conditions

To compare 10 Hz wide segments of the 0 to 1000 Hz frequency distributions of vibrations recorded from five stages of internally deranged and asymptomatic temporomandibular joints (TMJs).

TMJ vibrations were recorded from 236 patients with five stages of TMJ dysfunction: (1) reducing partial disc displacement (PDDR, n=39); (2) acute reducing complete disc displacement (A-DDR, n=39); (3) chronic reducing complete disc displacement (C-DDR, n=55); (4) un-adapted, non-reducing, complete disc displacement (DDUA, n=57); and (5) well adapted, non-reducing, complete disc displacement (DDWA, n=46). A totally asymptomatic control group with quiet TMJs (AQ, n=43) and a group with vibrating TMJs (AWV, n=93), but otherwise asymptomatic were also recorded. Frequency distributions were calculated for each group using discrete Fourier transform methods in 10 Hz increments (0-10 Hz, 10-20 Hz,…, 990-1000 Hz). The 10 Hz segments were compared between the seven groups using Student's t test with Bonferroni adjustment.

There were significant differences (P<0.05) in all 21 comparisons for the three segments between 80 Hz and 110 Hz, in 20 of 21 comparisons between 180 and 200 Hz, in 19 of 21 comparisons between 110 and 180 Hz and between 50 and 80 Hz.

The segments of the frequency distributions from 80 to 110 Hz provided the best differentiation between all seven groups.