Most elderly people's masticatory function decreases due to low oral function caused by aging or disease, and so they change their diet. This study aimed to examine the appropriate characteristics of test foods for masticatory function assessment, and to establish a simple assessment method for masticatory function based on masticatory performance for daily food items.
The subjects were 28 young people (20s) and 26 elderly people (70 years or more) living in the community. The pre-swallowing boluses of each test food item (dried apricots, sliced bread, cooked burdock roots, cooked chicken, kamaboko, boiled mushrooms, arares, boiled spinach, and teriyaki yellowtail) were collected. The particle size distributions in the bolus were analyzed, and the proportion of particles larger than 4.0mm after the first masticatory cycle was calculated using the number of masticatory cycles for each item.
It was shown that the proportion of large particles in the bolus increased as the values of occlusal condition parameters (contact area, maximum pressure, force) decreased, and as the number of masticatory cycles increased. These results suggest that the deficiency in masticatory function is compensated for by the increase of the number of masticatory cycles. We observed a correlation between the number of masticatory cycles and the proportion of large particles in the bolus in the case of cooked burdock roots, cooked chicken, arares, and teriyaki yellowtail. Arares showed insufficient similarities to other items and were considered inappropriate as test food items in this study. However, we used cooked burdock roots, cooked chicken and teriyaki yellowtail, which all had relatively high water content and relatively low adhesiveness, cohesiveness, and springness. Simple assessment of masticatory function may be possible by using test items with these characteristics, and by examining the number of masticatory cycles until swallowing.
Our assessment method required no special equipment or technique. This suggests minimal stress to the participants and limited investment on the part of the facilities. The application of our methods may be possible and useful at the nursing and care facilities for the elderly.

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Objective: In the present study, we attempted to clarify the relation between coronal restoration used on the approximal surface and the incidence and progression of periodontitis.
Methods: From the proving depth at the first dental visit of 101 patients, and the alveolar bone resorption observed on panoramic radiographs taken at the first dental visit of 289 subjects, the level of periodontitis at mesial and distal sides of each tooth was classified, and the distribution was compared by presence of coronal restoration for approximal surfaces.
Results: Prevalence of mild or heavier alveolar bone resorption was significantly higher in teeth with approximal fillings at all sextants of dentition in patients aged 20 to 49 years. For those aged 50 to 64 years, prevalence of moderate or heavier alveolar bone resorption was significantly higher in anterior teeth and premolar of upper and lower jaw with approximal fillings in patients aged 50 to 64 years. In patients aged 65 years and over, the significant difference in prevalence of alveolar bone resorption was observed only at limited sextants.
Discussion: The results suggest that teeth with filling on the approximal surface tend to initiate or progress periodontitis more frequently than non-treated teeth. Furthermore, they suggest that the effects of coronal restoration might have different specificity regarding the site and progression of periodontitis by age.
Conclusion: For prevention of periodontitis restorative filling on approximal surface should be avoided.

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[in Japanese]

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