The effects of conservative treatment on temporomandibular joint sounds and mandibular deviation during opening and closing movement of the mandible.

This study was undertaken to examine changes in temporomandibular joint (TMJ) sounds and mandibular deviations on opening and closing movements subsequent to conservative treatment of twelve patients presenting with mandibular dysfunction. A comparison of synchronous records indicated that two thirds of TMJ sounds were directly related to minor deviations in the path of movement of the mandible on opening and closing. TMJ sounds decreased significantly following flat plane splint therapy in all types, qualities and positions of sounds with the exception of those occurring near occlusal contact and those of a soft character. TMJ sounds related to minor mandibular deviations decreased significantly in all types, qualities and position of sounds except those of a soft nature. Fast Fourier Transform analysis of joint sounds consistently present before and after treatment revealed that the dominant frequencies were at the lower end of the acoustic range and that hard clicks have dominant frequencies higher than soft clicks.