The purpose of this study was to examine the relationship between objective and subjective assessments for declines of physical performances and oral function in elderly and to verify the siginificance of oral function and its subjective assessments as consciousness. Methods: The participants were 225 older adults. Maximum occlusal force, as indicators of oral frailty; and grip strength and walking speed, as indicators of physical frailty, were measured. Regarding the subjective assessments, 4 types of consciousness: “chewing well”, “legerity of walking”, “less fatigability”, and “much activity” were assessed by asking the present level when the level was assumed to be 100 at 20-year-old. The assessments on “chewing well”and “much activity” were comparatively high, then followed by “legerity of walking” and “less fatigability”. The siginificant relationships between the objective walking speed and subjective “legerity of walking” and between the objective occlusal force and subjective “chewing well” were found. The siginificant relationship of the objective walking speed with subjective “less fatigability, and “much activity” were found, but no relationship of the objective occlusal force was found. It is suggested the relationship between the objective and subjective assessments for occlusal force would be different from that of other physical performance, thus objective and subjective assessments on chewing would be required in the considerations of frailty.

Although thickening agents （TA） are frequently used in patients with dysphagia for the prevention of aspirating liquid and semisolid foods, the effects of adding TA on oral texture perception have not been elucidated. This study aimed to investigate the effect of TA on graininess perception of the liquid foods which contain fine solid particles. Graininess rec ognition threshold （GRT） was determined in 12 healthy individuals （aged 32.3±7.5 years） using the up-down staircase method. Aqueous suspensions （3 mL） of microcrystalline cellulose （average particle size: 50 µm） with （1 wt％ and 3 wt％）and without TA were used as the test foods. GRT increased significantly with TA concentration （Wilcoxon signed rank test, Bonferroni correction, p<0.0167）. In addition, the increment in GRT by adding TA tended to be greater in subjects who showed lower GRT at the testing that used test foods without TA. In a previous study, the authors revealed that GRT was lower in subjects with well-developed lingual papillae, and concluded that the vibration of the lingual papillae would be involved in the sensation of graininess. The results of the current study suggest that TA may suppress the vibration of the lingual papillae by agglomerating them, and may reduce graininess perception ability.

The purpose of this study was to clarify the usefulness of a newly developed prototype occlusal force measuring device. Using a calibration pressure device, seven types of loads from 100 N to 700 N were applied to the prototype occlusal force measuring device 20 times each 100 N, and the resistance values were recorded. With respect to 20 times of recorded data （reciprocal of resistance value）, changes over time were examined using a repeated measures analysis of variance. After calculating the calibration line （y=ax+b） from the first 10 recorded data, the pressure value was calculated by substituting the remaining 10 recorded data with y in this linear equation （x=（y－b）/a）. The coefficient of variation was calculated from the average value and standard deviation of the 10 measurements. Furthermore, the relative error （（measured value－theoretical value）/ theoretical value） was calculated. Next, 20 healthy subjects were asked to perform maximum clenching for 3 seconds using a bite force analyzing system （Dental Prescale II, GC）and a prototype occlusal force measuring device, and the maximum occlusal force was calculated. Then investigated whether there was any correlation between the two. The reciprocal of the resistance values for each load from 100 N to 700 N were approximately similar, and did not increase or decrease over time（F=1.481, p=0.106）. The calibration straight line obtained from the first 10 recorded data was y=0.5211x+59.329. The pressure value obtained from the remaining 10 recorded data approximated to the load value, and the coefficient of variation was less than 3 % and the relative error was less than 2 %. There was a statistically significant positive correlation between the maximum occlusal force measured using a prototype device and the maximum occlusal force measured using a Dental Prescale II （r=0.577, p=0.004）. From these results, it was suggested that the newly developed prototype occlusal force measuring device is useful and clinically applicable.