Reliability and validity of diagnostic modalities for temporomandibular disorders.

Temporomandibular disorders (TMD) encompass a group of musculoskeletal conditions that involve the temporomandibular joint (TMJ) or joints, the masticatory musculature, or both. These conditions are typically characterized by pain in the pre-auricular area that is usually aggravated by chewing or other jaw function and is often accompanied, either singly or in combination, by limitation of jaw movement, joint sounds, palpable muscle tenderness, or joint soreness. As with most other musculoskeletal conditions, the diagnostic "gold standard" for TMD is based upon an evaluation of the patient's history and clinical examination, supplemented, when appropriate, by TM joint imaging. It is against this "gold standard" that the reliability and validity of diagnostic modalities must be compared. With regard to electronic devices, several reviews of the scientific literature have concluded that the diagnostic reliability, validity, sensitivity, and specificity of such devices in the diagnosis of TMD have not been established. In addition, although clinical examination of the dentition may provide useful diagnostic information for some conditions, specific occlusal relationships have poor sensitivity and specificity when related to the presence or absence of TMD. TMJ imaging, when indicated, is useful in the detection of pathology within the joint, provided that validated criteria are applied to an analysis of the image. However, the assessment of condylar position as a diagnostic criterion for TMD has very poor reliability and validity.