lakodate 1998 
JE 
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MATERIALS AND METHODS 
Real-time ultrasonic image of the tongue was obtained 
using a 7MHz mechanical convex scanning transducer 
(MICRO PROBES PVF-738F, TOSHIBA) and ultrasonic 
(SONOLAYER SSA-250A). 
ultrasonic transducer was fixed below the chin to 
Focal depth used was 10cm. The 
make gentle contact with the skin. Real-time B-mode 
ultrasonic observation of the tongue was carried out 
in the median saggital plane of the mandible (Fig 
D. 
Thereafter, vertical motion of the dorsal surface was 
recorded as the M-mode on a line connecting the 
mandibular first molars. The picture in Fig. 2 was 
recorded VIR and simultaneously obtained by Line Scan 
Recorder. 
  
Fig 1. Fixation of ultrasonographic transducer 
and measurement point of tongue 
Submental 
skin 
  
Tongue surface 
10mm 
0.1s up 
Fig 2. B— and M — modes at resting position 
431 
Twenty healthy male volunteers participated in the 
first study. All subjects had complete natural 
dentition that included at least the second molars. 
None showed any signs or symptoms of problems in the 
stomatograthic system. Informed consent was obtained 
from each volunteer after a brief explanation of the 
study. The subjects were seated with the head 
straight and parallel between F-H plane and the 
floor. 
Firstly, we recorded each tongue position at rest and 
after swallowing the masticated peanut as B-mode. 
We measured the distance from the submental skin to 
the surface of the tongue on the line that linked 
right and left first molars in the saggital plane. 
The second measurements of the distance were carried 
out in volunteers at rest and the measurement error 
were calculated at rest. To confirm the tongue 
movement, the volunteers tapped ad-lib with their own 
teeth in an empty mouth and then masticated 
peanuts. We digitized a trace for 5 sec into 300 
points during tapping and peanut mastication, and 
statistically analyzed the average, standard 
deviation and coefficient of variation by the 
Wilcoxon signed-ranked test. 
Six of the 20 males were chosen for the next study. 
Test foods were rices steamed in eight degrees. The 
hardness and adhesiveness of each steamed rice were 
measured using texturometer. They were instructed to 
masticate freely, resting between the different test 
foods. Tongue movement was simultaneously recorded 
with a vertical motion trace of the mandibular 
kinesiograph. We visually inspected detailed data of 
tongue movement during mastication of each steamed 
rice, and measured the number and time of masticated. 
We digitized the trace for 1 sec from the beginning 
of mastication into 300 points, and statistically 
analyzed the coefficient of variation.