Abstract
The purpose of the this study was to observe through serial ultrasonic images the vertical motion of the tongue during mastication. Six male subjects with an average age of 28.7 and no evidence of neurological disorders volunteered for this experiment. The subjects were comfortably seated with the head straight and F-H plane parallel with a floor. A continuous, real-time image of the tongue was obtained using a 7MHz mechanical scanning transducer. The ultrasonic transducer was fixed below the chin to make gentle contact with the skin in relaxed position. Real-time B-mode ultrasonic observation of the tongue was made in the median sagittal plane of the mandible. Thereafter, karsol was established on the line that linked right and left first molars and the vertical motion of the tongue was recorded as M-mode. This transducer produced good quality images of the dorsal surface during mastication. Due to the small size and lightness of the transducer, image were continuously recorded without manipulation from the operator.
Results were as follows:
1. With visual inspection, it was confirmed that the vertical motion of the tongue has two stages; Which were interpreted as the sorting out phase (SO-phase), and the bolus formation phase (BF-phase) .
2. The most upper and lower points during mastication and the resting position were invariable within individuals.
