Editing Temporomandibular joint dysfunction (section)

===By cause and symptoms===
It has been suggested that TMD may develop following physical trauma, particularly [[Whiplash (medicine)|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).<ref name="Fernandez 2009" /> Sometimes muscle-related (myogenous) TMD (also termed myogenous TMD, or TMD secondary to myofascial pain and dysfunction) is distinguished from joint-related TMD (also termed arthogenous TMD, or TMD secondary to true articular disease), based upon whether the muscles of mastication or the TMJs themselves are predominantly involved. This classification, which effectively divides TMD into 2 syndromes, is followed by the American Academy of Orofacial Pain.<ref name="Medscape reference" /> However, since most people with TMD 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 temporomandibular disorders in 2 axes; axis I is the physical aspects, and axis II involves assessment of psychological status, mandibular function and TMD-related psychosocial disability.<ref name="Medscape reference" /> Axis I is further divided into 3 general groups. Group I are muscle disorders, group II are disc displacements and group III are joint disorders,<ref name="Manfredini 2011" /> although it is common for people with TMD to fit into more than one of these groups.