Investigators analyzing the data collected in the long-running clinical study Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) have now published their findings comparing individuals, all of whom were TMD free at the start of the study, with 260 individuals who developed first-onset TMD in the course of follow-up examinations. The papers, published as a special supplement to the December issue of the Journal of Pain (the official journal of the American Pain Society) indicate that a number of factors in many domains (e.g., genetic, environmental, physiologi