Influence of Vibratory Stimuli on the Perception of Mandibular Vertical Position

An investigation was carried out on the influence of vibratory stimuli on mandibular position sense during opening and closing movements. Eight subjects were instructed to memorized 4 reference positions that were 5, 10, 15 and 20mm from the intercuspal position (ICP) using mandibular kinesiograph. Then they were required to open and close their mouths 20 times', and this was repeated from superior or inferior to reference position to reproduce memorized position with their eyes closed. Then a 100Hz vibratory stimulus was applied for 20 seconds to the mentalis and the above jaw movements were repeated. After application of stimulus from above (closing approach), the perceived mandibular position became lower than the reference position. On the other hand, from below (opening approach), it became significantly higher. Twenty experimental sequences were significantly changed. During movement, the vibratory stimulus effect disappeared in the early stage. It was found that the mandibular position sense was affected by vibratory stimuli. It was suggested that the muscle spindle played an important role as the neuronal mechanism controlling mandibular position.