+ Classification: :::: Muscular: * Hyperactivity, spasm, and trismus * Inflammation (myositis) * Trauma * Myofascial pain and fibromyalgia * Atrophy or hypertrophy ::: Arthrogenic: * Disc displacement (internal derangement) * Hypomobility of the disc (adhesions or scars) * Dislocation and subluxation * Arthritis * Infections * Metabolic disease (gout, chondrocalcinosis) * Capsulitis, synovitis * Ankylosis (fibrous or bony) * Fracture * Absent, large, or small condyloid process * Neoplasia<unk>  is considered by some to be one of the 4 major symptom complexes in chronic orofacial pain, along with burning mouth syndrome, atypical facial pain and atypical odontalgia.<unk>  has been considered as a type of musculoskeletal, neuromuscular, or rheumatological disorder. It has also been called a functional pain syndrome, and a psychogenic disorder. Others consider<unk>  a "central sensitivity syndrome", in reference to evidence that<unk>  might be caused by a centrally mediated sensitivity to pain. It is hypothesized that there is a great deal of similarity between<unk>  and other pain syndromes like fibromyalgia, irritable bowel syndrome, interstitial cystitis, headache, chronic lower back pain and chronic neck pain. These disorders have also been theorized to be caused by centrally mediated sensitivity to pain, and furthermore they often occur together. Definitions and terminology Frequently,<unk>  has been treated as a single syndrome, but the prevailing modern view is that<unk>  is a cluster of related disorders with many common features. Indeed, some have suggested that, in the future, the term<unk>  may be discarded as the different causes are fully identified and separated into different conditions. Sometimes,<unk> " is described as the most common form of<unk>  disorder, whereas many other sources use the term<unk>  disorder synonymously, or instead of the term<unk> . In turn, the term<unk>  disorder is defined as "musculoskeletal disorders affecting the<unk><unk> s and their associated musculature. It is a collective term which represents a diverse group of pathologies involving the<unk><unk> , the muscles of mastication, or both". Another definition of<unk>  disorders is "a group of conditions with similar signs and symptoms that affect the<unk><unk> s, the muscles of mastication, or both."<unk>  disorder is a term that creates confusion since it refers to a group of similarly symptomatic conditions, whilst many sources use the term<unk>  disorders as a vague description, rather than a specific syndrome, and refer to any condition which may affect the<unk><unk> s (see table). The<unk><unk>  is susceptible to a huge range of diseases, some rarer than others, and there is no implication that all of these will cause any symptoms or limitation in function at all. The preferred terms in medical publications is to an extent influenced by geographic location. For example, in the United Kingdom, the term pain<unk>  syndrome is in common use. In the United States, the term<unk>  disorder is generally favored. The American Academy of Orofacial Pain uses<unk>  disorder, whilst the National Institute of Dental and Craniofacial Research uses<unk><unk>  disorder. A more complete list of synonyms for this topic is extensive, with some being more commonly used than others. In addition to those already mentioned, examples include<unk><unk>  pain<unk>  syndrome,<unk>  pain<unk>  syndrome,<unk><unk>  syndrome,<unk><unk>  syndrome,<unk><unk> ,<unk>  disorder,<unk>  syndrome, facial arthromyalgia, myofacial pain<unk>  syndrome, craniomandibular<unk>  (CMD), myofacial pain<unk> , masticatory myalgia, mandibular<unk> , and Costen's syndrome. The lack of standardization in terms is not restricted to medical papers. Notable internationally recognized sources vary in both their preferred term, and their offered definition. For example: By cause and symptoms It has been suggested that<unk>  may develop following physical trauma, particularly whiplash injury, although the evidence for this is not conclusive. This type of<unk>  is sometimes termed "posttraumatic<unk> " (pTMD) to distinguish it from<unk>  of unknown cause, sometimes termed "idiopathic<unk> " (iTMD). Sometimes muscle-related (myogenous)<unk>  (also termed myogenous<unk> , or<unk>  secondary to myofascial pain and<unk>  is distinguished from<unk> -related<unk>  (also termed arthogenous<unk> , or<unk>  secondary to true articular disease), based upon whether the muscles of mastication or the TMJs themselves are predominantly involved. This classification, which effectively divides<unk>  into 2 syndromes, is followed by the American Academy of Orofacial Pain. However, since most people with<unk>  could be placed into both of these groups, which makes a single diagnosis difficult when this classification is used. The Research Diagnostic Criteria (RDC/TMD) allows for multiple diagnoses in an attempt to overcome the problems with other classifications. RDC/TMD considers<unk>  disorders in 2 axes; axis I is the physical aspects, and axis II involves assessment of psychological status, mandibular function and<unk> -related psychosocial disability. Axis I is further divided into 3 general groups. Group I are muscle disorders, group II are disc displacements and group III are<unk>  disorders, although it is common for people with<unk>  to fit into more than one of these groups. By duration Sometimes distinction is made between acute<unk> , where symptoms last for less than 3 months, and chronic<unk> , where symptoms last for more than 3 months. Not much is known about acute<unk>  since these individuals do not typically attend in secondary care (hospital).
Temporomandibular joint dysfunction
Impacted wisdom teeth
Facial nerve paralysis
Eustachian tube dysfunction
Orofacial myofunctional disorders
Barodontalgia
Ear pain
Orofacial pain