The most common reason patients seek medical or dental care in the United States is due to pain or dysfunction. The orofacial region is plagued by a number of acute, chronic, and recurrent painful maladies. Pain involving the teeth and the periodontium is the most common presenting concern in dental practice. Non-odontogenic pain conditions also occur frequently. Recent scientific investigation has provided and explosion of knowledge regarding pain mechanisms and pathways and an enhanced understanding of the complexities of the many ramifications of the total pain experience. Therefore, it is mandatory for the dental professional to develop the necessary clinical and scientific expertise on which he/she may base diagnostic and management approaches. Optimum management can be achieved only by determining an accurate and complete diagnosis and identifying all of the factors associated with the underlying pathosis on a case-specific basis. A thorough understanding of the epidemiologic and etiologic aspects of dental. musculoskeletal, neurovascular, and neuropathic orofacial pain conditions is essential to the practice of evidence-based dentistry/medicine.