In order to clarify the mechanism of response in the autonomic nervous system and hematological-biochemical constituents during gum chewing (G), this study examined changes in oxygen uptake (VO₂), blood pressure (SBP, DBP), heart rate (HR), plethysmogram wave height (WH), coefficient of variation (CV_RR, CV_WH), plasma catecholamine (pAd, pNorad), dehydro-epiandrosterone (DHEA), blood lactate (LA), non-esterified fatty acid (NEFA) and triglyceride (TG) associated with gum chewing, and compared the results obtained during dynamic handgrip (H). Ten healthy male volunteers (23.6±4.2yrs) chewed three kinds of gums with different hardness (I, II, III) for 6 minutes at each intensity, and also performed dynamic handgrip with the same V 0₂ during G, using the same protocol as with G on another day. Exercise was performed in the supine position by all subjects.
Results were as follows:
1. SBP, DBP and HR increased and WH decreased during G more than during H. This pattern was typically observed at a low intensity of exercise. Initial responses of DBP and WH were more marked at G than at H.
2. pAd, pNorad and pDHEA concentrations were enhanced after both G and H exercises. However, LA concentration after G was less than after H at the same intensity of exercise.
3. There was no significant difference in CV_RR, CV_WH and NEFA changes between G and H.
4. Increases in SBP and DBP were correlated with a rise in pDHEA concentration, and WH decrease was significantly correlated with TG concentration reduction in G exercise, but these correlations were not noted in H exercise.
These findings suggested that sympathetic nerve activity was enhanced by both the exercise of gum chewing and dynamic handgrip, but that gum chewing increased blood pressure more extensively and faster than handgrip, indicating that peripheral sympathetic nerves were activated more rapidly in gum chewing, however, at a low intensity of exercise. It was estimated that these rapid and strong responses based on the nervous system network involved masseter muscle contraction in chewing.

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The influence of periodontal condition upon masticatory function has not been well evaluated yet. In this study we first planned to obtain the fundamental relationship between masticatory function and occlusion in periodontally healthy subjects. Forty-four subjects (21 males and 23 females) with more than 28 teeth with no signs of periodontitis or no occlusal dysfunction were selected. Masticatory function was evaluated using a color-changeable chewing gum and expressed as masticatory performance. Occlusal measurements, including occlusal platform area, average bite force, total bite force, and occlusal balance, were determined by Dental Prescale System ^®. The results showed that the masticatory performance in the male subjects was significantly greater than that in the female subjects. Furthermore, the masticatory performance significantly correlated with average bite force and occlusal platform area. However, when the male and the female subjects were separately analyzed, these associations were observed only in the male group, while the female group showed a significant association only between masticatory performance and occlusal balance. The present study demonstrated the relationship between the masticatory function measured using the color-changeable chewing gum and the occlusal measurements determined by Dental Prescale System ^® in periodontally healthy subjects. It is necessary to study the relationship between masticatory function and occlusion in periodontitis patients.

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An infantile obesity resolution seminar was monthly held targeting obese children. Since the eating habits of mothers greatly influence the eating habits, and ultimately obesity of their children, participation of mothers were required, as a rule. The seminar involved a program comprising medical examination, nutrition guidance, dental examination/chewing instruction and exercise instruction, especially focusing on the instruction to “take the time in tasting the meal through 30 chewings per mouthful.” Most of the children who showed abnormal values in blood biochemistry at start of the seminar showed normal values at completion of the seminar. The children whose number of chewings per mouthful was increased to 20 or more times at completion of the seminar significantly decreased the body fatness in comparison with those remaining to chew less than 20 times. Despite the same education/instruction provided in the seminar, the difference in increase in the number of chewings gave birth to the difference in decrease in the degree of obesity; the consciousness of chewing was reflected in the difference in the number of chewings. The number of chewings and the time of food retaining in the oral cavity serve as a contributing factor of the satiety signal. More chewings stimulate satiety, independent of calorie, leading to expected resolution of obesity. Therefore, it is effective in resolving obesity to raise the children's consciousness of chewing, through instruction to “chew the food well before swallowing them” in the early stage or under junior high school age, when chewing ability is in the process of developmerit.

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The study aims to clarify what kind of masticatory abilities relate the individual difference in masticatory electromyogram (EMG) of the kelp. The kelp sample contains plenty of fibers, and requires high masticatory quantity. Subjects with high crushing ability tested a gumbase sample, which is a piece of brittle gum-base fabricated specially, masticated the kelp in the short time. Subjects who have larger contact area under near masticatory pressure, and higher masticatory pressure showed high EMG activities at one chew movement. It was shown that subjects who have smaller contact area over 10MPa measured with Dental Prescale system need high muscle activities until swallowing the kelp. Mixing ability by the chewing gum method did not reflect any mastication parameters in EMGs of the kelp. It is necessary that high ability of crushing hard sample and large contact area to masticate fibrous food in order to improve the mastication quantity. These abilities are independent to the mixing ability of the soft food.

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