Abstract
It is necessary to observe all processes from food crushing to formation of swallow-able food bolus in order to evaluate the whole masticatory function. Many researchers reported various evaluation of chewing function. But, most of these reports discussed only the evaluation of crushing function. Therefore, this study is designed to develop a method to evaluate the masticatory function including bolus formation.
The bolus formation is thought to be related to two functions, one is the saliva secretion function, and the other is the lingual transport function. In this study, therefore, the relation between the bolus formation function and the number of chewing strokes until swallowing rice crackers with different absorbency was examined. Twenty-one normal healthy subjects (14 male, 7female) were selected for this study. The lingual transport ratio and the degree of crushing were measured using 3-gram peanuts. Moreover, the numbers of chewing strokes until swallowing a piece of rice cracker was counted. The amount of saliva was measured using a piece of wax stick for saliva secretion test. The correlation between the number of chewing strokes and the amount of saliva was analyzed. The correlation between the number of chewing strokes and the lingual transport ratio was also analyzed.
The results were as follows: 1) A negative correlation was proven between the amount of saliva and the number of chewing strokes until swallowing, and a little number of chewing strokes tended to be recorded in the subjects with high saliva secretion ability; 2) A negative correlation was proven between the lingual transport ratio and the number of chewing strokes until swallowing. In the subjects with high lingual transport ratio a few number of chewing strokes tended to be recorded; 3) The above-mentioned relations were remarkable in the rice cracker with large amount of water absorption.
From these results, the saliva secretion and lingual transportation that are related to the bolus formation were able to be predicted by this method, counting the number of chewing strokes until swallowing of water absorbing rice crackers. This means that the evaluation of masticatory function, including bolus formation, can be achieved by this method.
