A Study of Factors Affecting the Masticatory Ability of the Elderly

One of most important objectives of the 8020 movement is to maintain people's masticatory ability. Many surveys have shown that a large number of remaining teeth is helpful in maintaining masticatory ability. However, clinical experience indicates that there have been many cases in which masticatory ability cannot be accounted for by the number of teeth alone. In other words, to maintain the masticatory ability of the elderly, we must investigate causes other than the number of teeth. Accordingly, in this study we report on an analysis of physical functions of the whole body, beyond the oral area, which influence masticatory ability. The data used in this study was gathered as a part or the project “Longitudinal Interdisciplinary Study on Aging, TMIG-LISA”. This is a ten-year longitudinal study by the Tokyo Metropolitan Institute of Gerontology, began at April 1991.<BR>The subjects were 220 males, living in Nangai village, Yuhoku-gun, Akita Prefecture, who were all between the ages of 65 and 84 at the preseut on June 1, 1992. Of the aspects inves-tigated in this survey, the three oral aspects were the number of natural teeth, the number of functional teeth, and the masticatory ability, tested by G-1 jelly. Other physical functions inve stigated were movement (grasping, balance, walking speed) and age. The Hayashi's quan-tification method of the third type was used to analyze the results, to collect qualitative data on the masticatory function and to handle the data.<BR>1. The defference between masticatory function level 1 (difficulty in chewing daily food) and masticatory function level 3 (able to chew daily food) appeared to be due to the difference in the number of functional teeth.<BR>2. The defference between masticatory function level 5 (able to chew most kinds of food) and masticatory function level 3 seems to be related to the amount of exercise, and to the person's age.<BR>Thus, the supply of dentures by the dentist, which effectively increases the number of functional teeth can move people from masticatory function level 1 to level 3. However, to maintain people in level 5, the most effective means is not only the maintenance of the number of natural teeth by oral care. The most important factor for people in level 5 appears to be their general physical condition, especially their mobility.