The relationship between masseter muscle pain and T2 values in temporomandibular joint disorders.

OBJECTIVE: Myofascial pain in temporomandibular joint disorders (TMDs) is evoked by various factors, including edematous change. We investigated whether the pain pattern is related to edematous change by using T2 mapping generated by magnetic resonance imaging to detect water content in the tissue. STUDY DESIGN: One hundred and five patients diagnosed with TMDs, with or without unilateral masseter muscle pain, were divided into 6 groups according to their pain experience: pain on compression (23 cases), pain on movement (13 cases), spontaneous pain (4 cases), pain on compression and movement (14 cases), pain on compression and spontaneous pain (2 cases), and no pain (49 cases). Differences in the mean T2 values of the masseter muscle between the group with pain on only one side (5 unilateral pain groups) or pain-free on both the right and left sides (pain-free group) were compared with paired t tests. Significant differences were assumed at P < .05. RESULTS: Significant differences in mean T2 values were found between the painful and pain-free sides in the group with pain on compression. CONCLUSIONS: The findings of edematous change in the masseter muscle of patients with pain on compression may affect treatment planning and lead to investigation of treatment options for myofascial pain in TMDs.