Orofacial pain is a general term covering any pain which is felt in the mouth, jaws and the face. Orofacial pain is a common symptom, and there are many causes.Orofacial pain is a relatively common condition in the patients seeking care from general dentists,pain in the muscles and temporomandibular joints was found as frequently as that in the teeth and surrounding tissues. Orofacial pain has been defined as "pain localized to the region above the neck, in front of the ears and below the orbitomeatal line, as well as pain within the oral cavity; [including] pain of dental origin and temporomandibular disorders".[3] However, some orofacial pain conditions may involve areas outside this region, e.g. temporal pain in TMD. Toothache, or odontalgia, is any pain perceived in the teeth or their supporting structures (i.e. the periodontium). Toothache is therefore a type of orofacial pain. Craniofacial pain is an overlapping topic which includes pain perceived in the head, face, and related structures, sometimes including neck pain Orofacial pain (OFP) is defined as pain whose origin is below the orbito-meatal line, above the neck and anterior to the ears, including pain within the mouth. Chronic Orofacial Pain represents a complex pain condition with an etiology comprised of many factors including those falling within biological, psychological, and social domains. The complexity of this condition underscores the urgency to evaluate these domains from an integrative perspective rather than one that simply addresses the potential etiological mechanisms in a singular fashion. Indeed, a review of the trajectory of this pain condition reveals a dynamic pathway in which numerous factors seemingly play a role in its manifestation, as well as its chronicity. By definition, “chronic” orofacial pain represents a pain that has persisted for a period of time that is longer than the believed recovery time for that body site to heal. Approximately 40-70% of the US reportedly demonstrates a symptom of orofacial pain, and 10% meet the criteria for having COP to the point that it is considered disabling and is significantly compromising activities of daily living. The intention of this paper will not centre on providing an exhaustive review, but instead, to highlight key features of COP from a biopsychosocial perspective. Specifically, the transition that lead orofacial pain from the acute to the chronic stage will be reviewed by underscoring well established mechanisms believed to facilitate this transition. Embedded in this discussion, the psychophysiological mechanisms that are less established in the manifestation of COP will also be reviewed. These mechanisms may distinguish COP from other types of pain. Much of the data presented stem from studies that have included a wide range of orofacial pain conditions including, but not limited to, temporomandibular disorders, trigeminal pain, and headaches. Assessment of the Psychological Comorbidity, Pathophysiological Mechanisms, and Treatment Implications in Patients with Chronic Orofacial Pain