TMD is considered by some to be one of the four major symptom complexes in chronic orofacial pain, along with
burning mouth syndrome,
atypical facial pain and
atypical odontalgia. TMD has been considered as a type of
musculoskeletal, or
rheumatological disorder. It is hypothesized that there is a great deal of similarity between TMD and other pain syndromes like
fibromyalgia,
irritable bowel syndrome,
interstitial cystitis, headache, chronic lower
back pain and chronic
neck pain.
Definitions and terminology Frequently, TMD has been treated as a single
syndrome, but the prevailing modern view is that TMD is a cluster of related disorders with many common features. whereas many other sources use the term 'temporomandibular disorder' synonymously, or instead of the term 'temporomandibular joint dysfunction'. In turn, the term 'temporomandibular disorder' is defined as "musculoskeletal disorders affecting the temporomandibular joints and their associated musculature. It is a collective term which represents a diverse group of pathologies involving the temporomandibular joint, the muscles of mastication, or both". Another definition of temporomandibular disorders is "a group of conditions with similar signs and symptoms that affect the temporomandibular joints, the muscles of mastication, or both." 'Temporomandibular disorder' is a term that creates confusion since it refers to a group of similarly symptomatic conditions, whilst many sources use the term temporomandibular disorders as a vague description, rather than a specific syndrome, and refer to any condition which may affect the temporomandibular joints (see table). The temporomandibular joint 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. Only 33% of those with signs of TMD will have symptoms. The preferred terms in medical publications is to an extent influenced by geographic location. For example, in the
United Kingdom, the term 'pain dysfunction syndrome' is in common use. Axis II assessments allows clinicians to evaluate the impact of TMD on quality of life in the process of diagnosis, and treatment planning. It has been suggested that TMD may develop following physical trauma, particularly
whiplash injury, although the evidence for this is not conclusive. This type of TMD is sometimes termed "posttraumatic TMD" (pTMD) to distinguish it from TMD of unknown cause, sometimes termed "
idiopathic TMD" (iTMD).
By duration Sometimes distinction is made between acute TMD, where symptoms last for less than three months, and chronic TMD, where symptoms last for more than three months. Not much is known about acute TMD since these individuals do not typically attend in
secondary care (hospital). ==Signs and symptoms==