Purpose/Objective of this study? TMJD represents a prototypic musculoskeletal disease whose characteristics of associated depression, comorbidity of fibromyalgia, female prevalence, increased CNS sensitivity to pain, and likely genetic differences among susceptible individuals, makes it a disorder that will likely be responsive to duloxetine treatment.The overall objective is to investigate duloxetine as a potential treatment for chronic pain of TMJD. We hypothesize that subjects receiving duloxetine will experience greater analgesia than those receiving placebo.