2006 Volume 10 Issue 3 Pages 231-238
This study examined the appropriate characteristics of test foods and the influence of the swallowing threshold on the assessment, in order to establish a simple method for assessing masticatory function based on the number of masticatory cycles.
The subjects were 28 young people (in their 20s) and 26 elderly people（70 years or older）living in a community. Their occlusal condition parameters (contact area, maximum pressure, total force, and force of the first molar) were measured. The pre-swallowing boluses ef each test food (dried apricots, sliced bread cooked burdock roots, cooked chicken, kamaboko, boiled mushrooms, arares, boiled spinach, and teriyaki yellowtail) were collected to analyze the characteristics of the boluses：particle size distribution, texture (hardness, cohesiveness, adhesiveness, resnience) and water content. The number of masticatory cycles till swallowing was counted. To find the regression equations of the number of masticatory cycles, the parameters of occlusal condition and the characteristics of the boluses were analyzed as explanatory variables using multiple regression analysis.
The regression equations of the number of masticatory cycles were found for cooked burdock roots and boiled spinach. From the equations, it was clarified that the contact area and maximum pressure influenced the chewing number of cooked burdock roots, and the force of the first molar influenced the chewing number of boiled spinach. The number of masticatory cycles increased as the values of their parameters decreased. However, the particle size distribution and texture had a stronger influence. Correlations between the parameters and number of masticatory cycles were observed. It was considered that these foods were masticated until their own swallowing thresholds.
The method for assessing masticatory function based on the number of masticatory cycles using cooked burdock roots and boiled spinach was found to be valid. However, it was clarified that the particle size distribution and texture had a stronger influence than the occlusal conditions. To assess the masticatory function based on the number of masticatory cycles using these foods, it is necessary to consider their swallowing thresholds carefully.
