Journal of Dental Research, Vol 66, 1389-1392, Copyright © 1987 by International & American Associations for Dental Research Online Journals
Timing of temporomandibular joint sounds in orthodontic patients
Z. F. Muhl, C. Sadowsky and E. I. Sakols
The consistency of occurrence and also the timing of TMJ sounds during jaw
opening and closing were studied by means of an audio-visual sound
recording system in an attempt to address the possible causes of
temporomandibular joint (TMJ) sounds. From a group of 347 orthodontic
patients, 104 were found to have medium- or high-amplitude TMJ sounds
during jaw opening or closing. Most patients (53%) had reciprocal
clicking--that is, a single sound on opening and on closing; another 12%
had multiple sounds on opening or closing; 22% had a single closing sound;
and 13% had a single opening sound. Sounds occurred at all degrees of jaw
opening throughout this sample, but in most patients opening sounds tended
to be closer to maximum opening, whereas closing sounds tended to occur in
the middle of the closing movement. No statistically significant
association was found between the timing of the opening and closing sounds.
In 42.3% of patients, the sound was inconsistent in its occurrence on
successive opening and closing cycles. Twenty-three percent of patients
reported pain, jaw locking, or limitation of movement, but these were not
associated with the timing of the opening sound. The findings suggest that
the reciprocal click, widely associated with anterior disc displacement
with reduction, was relatively common, but that other explanations for the
joint sounds should also be considered. Conversely, a large variation may
exist in the timing and the occurrence of sounds in patients with anterior
disc displacement in the absence of pain and limitation of movement.
