Document Type: Original Article


Assistant Professor, Department of Oral Medicine, School of Dentistry, Shiraz University of Medical Sciences


Pain is one of the most commonly experienced symptoms in medicine and, as such, is a major concern to the physician. The word pain has been used by almost every one and has been described by a variety of terms and according to personal past experiences and memories of it. Pain is not only considered as a specific sensation associated with actual or potential tissue damage but also depends on cultural background, cognitive, motivational and affective factors, personality, attention and so on. Being so, with the full knowledge that any definition for pain is arbitrary and open to question, one may define pain with its multidimensional nature as an unpleasant sensation created by a noxious stimulus which acts as a protective mechanism. Pain not only includes a sensory discriminative component but also involves the accompanying reaction elicited by the stimulus. So, the study, diagnosis, and treatment of pain requires the recognition of all those factors related to the pain experience. Accordingly, familiarity with stimulation and measurement techniques and theories of pain and their related mechanisms, will be a necessity to apply pain control procedures. The purpose of this article is a relatively comprehensive review in pain continuum and its specifications based on biologic principles with the emphasis on relationship of pain mechanisms with oro-facial areas. Key words: Pain Definition, Noxious Stimuli, Pain Theories and Mechanisms