Using the Kinesiograph to measure mandibular movements during speech: a pilot study.

This study was a pilot investigation to determine a method of measuring mandibular movement during speech using the Kinesiograph. Some observations and trends were evident. 1. The Kinesiograph is an excellent instrument for measuring mandibular movement in three dimensions. 2. Production of the /s/ sound can occur anywhere within a three-dimensional range rather than at one position. 3. The distance between the upper and lower incisors during speech was much less than 1 mm and was consistent throughout the range used by each subject. 4. The functional angle of mandibular movement during speech to the maxillary occlusal plane was essentially the same as the angle of rest position to centric occlusion and appeared to be related to the cephalometric occlusal plane angle. It seems likely that rest position is the key to functional mandibular movement. 5. Three-dimensional clinical studies of mandibular movement during speech using the Kinesiograph could lead to more precise answers to questions concerning mandibular function and occlusal dysfunction.