Abstract
The purpose of this study was to evaluate the effect of the water contents of the food and food bolus on the chewing time in five-year-old children.
The subjects were 10 boys and 10 girls who had normal primary dentitions. The food selected was steamed rice, sausage, mashed potatoes, cookies, apples and pickled radish. The subjects took the usual bite size portions of the food and chewed until such time as they would normally have swallowed, but instead of swallowing, they spat out the food bolus into a weighed container. The time required for all the food to be masticated and spat out was recorded. The volume of saliva secreted duling that time was determined by subtracting the initial weight of the food from that of the food saliva mixture. The water content of the initial food and food bolus was determined after freeze-drying. The percent of food swallowed or retained in the mouth was calculated by the formula described by Watanabe et al.
The mean chewing times per 1 g of each food was inversely related to the initial water content of the food (r=-0.68, p<0.05). The percent of the water content of the food after chewing showed significant correlation to the initial water content of each food (r=0.83, p<0.01). The percent of the water content of the food bolus in the same subjects showed constant values with low standard deviation. These results suggests that the water content of the food bolus may be a factor in the decision to swallow and the initial water content of food is also an important factor regarding the salivary flow and chewing time per 1 g of food. This study was supported by a Grant-in-Aid for Scientific Research (02807189,05671719)from the Japanese Ministry of Education to S. W.
