Electromyographic and kinesiographic study in patients with nonreducing disk displacement of the temporomandibular joint

Objective. The purpose of this study was to clarify electromyographic and mandibular kinesiographic properties of the chewing movement in patients with unilaterally painful nonreducing disk displacement of the temporomandibular joint. Study design. Chewing movement in 50 female patients was evaluated by electromyograph and mandibular kinesiograph, and the results were compared with those in 31 normal controls. Results. In the analysis by electromyograph, some differences between patients and controls were found. In the analysis by mandibular kinesiograph, chewing movement showed deviation to the chewing side in the TMI-affected-side chewing but did not show deviation in the TMI-unaffected-side chewing in the horizontal plane. The maximal anteroposterior width between opening and closing paths in the sagittal plane was smaller in the experimental subjects. Conclusion. These differences between patients and controls may be helpful to diagnosis for painful nonreducing disk displacement of the temporomandibular joint.