An evaluation of the relationship between temporomandibular joint sounds and mandibular movements.

Mandibular movements in 28 subjects with TMJ sounds (who were otherwise asymptomatic) were evaluated and compared to those of 28 control subjects with no signs or symptoms of TM disorders (including the absence of clinically detectable TMJ sounds). Mandibular movements were recorded using the Sirognathograph interfaced with a personal computer. The joint sounds were recorded with contact microphones. The variables used to measure mandibular movements were not statistically different between the two groups except for mean mandibular deviation in the frontal plane, which was greater in the study group (3.2 mm) than the control group (2.2 mm). All combinations of mandibular movements were found to occur in relation to joint sounds with no obvious pattern. The large variability in both the study and control subjects, combined with the frequent finding of joint sounds in normal subjects, indicates that caution should be exercised in interpreting the characteristics of electronically recorded mandibular movements and TMJ sounds.