Can Concomitant Masticatory Muscle Contraction Interfere with Temporomandibular Joint Arthralgia Evaluation?

AIMS: To investigate the effect of masticatory muscle contraction on the pressure pain threshold (PPT) of the lateral pole of the temporomandibular joint (TMJ) in patients with TMJ arthralgia and in asymptomatic individuals. METHODS: A total of 72 individuals divided into two groups (group 1: patients with unilateral TMJ arthralgia [n = 36]; group 2: control group, asymptomatic individuals [n = 36]) were compared. The PPT of the lateral pole of the TMJ with and without concomitant masticatory muscle contraction was determined using a digital algometer in both groups. Paired and independent Student t test were used to compare the data within and between groups, respectively. A 5% significance level was used for all tests. RESULTS: Higher TMJ PPT values with concomitant masticatory muscle contraction were found in both groups (P < .001). The amount of increase in PPT with contracted muscles was not significantly different between groups (P = .341), but the TMJ arthralgia group had significantly lower PPT values than the control group regardless of muscle contraction status (P < .001). CONCLUSION: Concomitant masticatory muscle contraction significantly increased the PPT of the lateral pole of the TMJ in relation to relaxed muscles, regardless of the presence of arthralgia.