Temporomandibular joint dysfunction (TJD) is a term applied to a group of problems that affect the muscles of mastication, the temporomandibular joint, and their supporting structures. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, deals only briefly with TMD in Section 11.4b, noting that this dysfunction may impede mastication, affect speech, cause lower facial deformity, and produce pain. Objective criteria (disk displacement and radiographic evidence of joint degeneration, range of motion [ROM], and surgical intervention) have been used to diagnose TMD, but the AMA Guides, Fifth Edition, usually bases the diagnosis on dietary restrictions or problems with speech. A table in the article provides a description of disk displacement and joint degeneration; based on symptoms, clinical findings, and imaging results, examiners can place the patient in one of five stages. Evaluators should use generally accepted ROM measurement principles, and the reproducibility of active ROM is an important indicator of measurement accuracy. Surgical correction includes arthroscopy or arthroplasty. Challenges in developing a process for rating TMD impairment include what factors relate to impairment, what should be the range of impairment, and who should perform the rating. At present, the AMA Guides states that “permanent impairment requires a medical assessment performed by the physician.”

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