AIMS: To identify differences between 2 groups of patients with temporomandibular disorders (TMD), those with masticatory muscle pain (MMP) versus intracapsular pain (ICP), and to compare these differences on behavioral and psychosocial domains. METHODS: There were 435 patients in the MMP group and 139 patients in the ICP group. The overall sample was 88.2% female and had an average age of 36.1 years (SD = 11.7). Patients completed measures of psychological symptoms (SCL-90), pain severity (MPI), sleep (PSQI), activity (MBI), and life stressors (PCL). Heart rate and blood pressure were also measured, and a complete medical/dental history was taken for each patients

RESULTS: Results indicated no significant difference in pain severity or duration between the 2 groups (P > 05). The ICP group, however, reported fewer affective symptoms of pain than the MMP group (t = 6.8, P =.01). The ICP group had twice as many adaptive copers as dysfunctional patients (chi 2 = 7.84, P <.01), while there was no significant difference between these 2 categories for the MMP group (P >.05). Finally, the ICP group reported fewer psychological symptoms (P <.05), better sleep quality (F = 7.54, P =.01), and fewer life stressors (F = 7.00, P =.01) than the MMP group

CONCLUSION: In contrast to many previous studies, the data set in this study showed no differences in pain severity and duration between the MMP and the ICP groups. Even though pain severity levels were equivalent, the MMP diagnostic group of chronic TMD patients demonstrated more dysfunctional behavioral profiles and significantly higher psychological distress than the ICP subgroup