Temporomandibular joint disorders (TMJD) are a family of musculoskeletal disorders that represent the most common chronic orofacial pain condition. TMJD is associated with persistent pain in the region of the temporomandibular joint and muscles of the head and neck. The purpose of this study is to test duloxetine (Cymbalta) as a potential treatment for chronic facial pain. Duloxetine is FDA approved as an antidepressant and for the chronic pain conditions of fibromyalgia and diabetic neuropathy. Chronic facial pain may be linked to Temporomandibular Joint Disorder (TMJD) which currently has no standard treatment.