Temporomandibular joint sounds: a critique of techniques for recording and analysis

Sonography, or the graphic recording of sounds, has been proposed as an objective measure of various pathological conditions in the temporomandibular joint. Various electronic devices have been developed to enhance our ability to auscultate the joint, monitor the timing of the sounds with jaw movement, and analyze the characteristics of the sound; the intent of these devices is to diagnose the intracapsular condition "objectively." This review paper critically evaluates the advantages and limitations of this technique. Based on the existing literature, these instruments can record sounds; however, the origin of these sounds is uncertain, since room noise, skin and hair sounds, respiration, arterial blood flow, and cross-over noises from the opposite TMJ have not been excluded as possible artifacts of the recording. More important, the diagnostic specificity, as an indicator of each type of TMJ disease, has not been clearly and consistently demonstrated with the sonographic technique.