CORRELATION OF THE CHARACTERISTICS OF TEMPOROMANDIBULAR-JOINT AND TOOTH CONTACT SOUNDS

In this study tooth contact sounds have been compared with temporomand ibular joint (TMJ) sounds elicited during opening and closing movement s. One hundred and eight subjects were instructed to open as far as po ssible and then close with sufficient force to produce a tooth contact sound. At least four cycles from each subject were recorded on tape, The first and last sounds in the recording were the tooth contact soun ds, these were identified automatically. The mean duration and rise ti me of each tooth contact sound was calculated and their standard devia tions for each subject were calculated to give a measure of the reprod ucibility. The number and mean amplitude of TMJ sounds occurring durin g tooth separation were also calculated for each cycle. Highly signifi cant correlations were found between the number and amplitude of the T MJ sounds within a cycle and the duration and rise time, and particula rly their standard deviations. Acoustic quiescence during the open-clo se cycle was associated with short, reproducible tooth contact sounds characterized by a short rise time. The longest and most variable toot h contact sounds were associated with TMJ sounds in all three phases o f the open-close cycle. This supports previous clinical findings assoc iating occlusal interferences with TMJ dysfunction.