We are aiming to develop elderly-friendly living environment. For this purpose, we developed a symbiotic robot (SR) utilized as the health care system. In order to have the SR act as the interface with residential living space, we realized the housing operations controlled by a user's voice. The SR extracts the user's emotional information from his/her voice which controls the home operation, and changes its own color in accordance with his/her emotion. It can also speak the user's language using a voice-synthesis technology. The SR is also equipped with a biological information monitoring system for the health care of the elderly. This monitoring system performs non-invasive measurement for respiratory rate and heart rate using the low-frequency pressure sensor. This information is sent to the SR for analysis and recorded. According to our test, the result of measurements in respiratory rate and heart rate showed a good correlation with conventional methods, and we proved that it can be utilized as an index for physiological function. In addition, the ear canal pressure changes obtained from the user's ear plugs that are connected to the low-frequency pressure sensor showed unique changes. This ear canal pressure changes are found to be possible to reflect changes in jugular vein pressure or right heart hemodynamics. These data were expected to provide an important physiological evidence for the cardiac disease. This monitoring system can be applied to a practical use as a device for non-invasive diagnosis of right heart function.

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The objective of this study was to clarify the relationship between lip-closing function, which was evaluated by lip-closing force (LCF) measured by the novel developed multidirectional LCF measurement system, and lip morphology or anterior teeth occlusion in the early stage of permanent anterior teeth occlusion. In 242 primary school children (136 boys, 106 girls, mean age = 10.3 ± 0.3 years), LCFs in eight directions during maximum voluntary pursing-like lip closure tasks, Overjet (OJ), overbite (OB) and a lateral facial snapshot were recorded in three primary schools in Nagano. The presence of the shrinkage of the chin skin at rest (contraction) was evaluated during taking a facial snapshot. From lateral facial snapshots, the ratios of heights of the lips including upper labial, vermillion and lower labial ratios (proportions of part of the lips relative to the total labial height obtained through the planes perpendicular to the Frankfurt plane) were evaluated. Correlation analyses were performed between LCF and these morphological variables. There was a weak correlation between [Upper] {the proportion of directional LCF from upper direction to total LCF (TLCF)} or [Upper + Lower] and OJ in girls and between TLCF and lower labial ratio in both genders. TLCF and DLCF obtained from lower direction in boys with contraction were significantly smaller than those without contraction. We concluded that the focal lip morphology and the characteristic of anterior teeth occlusion are related-factors to LCF.

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Occlusal splints are commonly used for treatment of sleep bruxism. However, there is no clear consensus on the mechanics of action and the best design of occlusal splint. One possible reason is due to the extremely dificulty in measuring and analyzing jaw movements during sleep. In this study, the six-degree-of-freedom jaw tracking system for sleep study constructed with the jaw tracking device using intra-oral sensors, an ambulatory polysomnograph and an AV monitor was employed to record jaw movements during sleep and analyze vertical component of resting jaw position at the incisal point in the supine position. We then examined the association between the vertical positions and the frequencies of sleep bruxism events. Twelve healthy adult subjects (7 males, 5 females; mean age 25.5 ± 5.7 years) without sleep disorder or stomatognathic dysfunction and with individual normal occlusion were participated in this study. Their jaw movements during sleep were recorded for two nights. To avoid the inclusion of the first night effect, the data from the second night were used for analysis. Since all participants got excellent sleep, the inluence of this system on sleep was a minimum. The mean vertical jaw position was 2.9-6.0 mm. Although vertical jaw position was not affected by sleep stages, there were significantly more epochs with a vertical jaw position of 2.5-5.0 mm in stage 1 (P<0.05) and significantly more epochs with a vertical jaw position of 2.5-5.0 mm or ≥ 5.0 mm than those with < 1.0 mm or 1.0-2.5 mm in stage REM, 2, 3&4 (P<0.05). Epochs with a vertical jaw position of ≥ 2.5 mm accounted for 84.2 ± 16.3% of all epochs. There was a negative correlation between mean vertical jaw position and frequency of sleep bruxism (R² = 0.705, P<0.05). The results suggest that humans maintain vertical jaw opening during sleep throughout the night and the vertical jaw position can be used as a certain reference value to decide the occlusal thickness of splint for treatment of sleep bruxism.

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The objective of this study was to clarify the characteristics of lip-closing force (LCF) measured by the multidirectional LCF measurement system and evaluate the relationship between LCF and age, physiques, handgrip strength and dentate status in healthy elderly persons. In 139 subjects (77 females, 62 males, mean age = 69.6 ± 5.2 years), LCFs in eight directions during maximum voluntary pursing-like lip closure tasks, height, body weight, handgrip strength, dental status and the usage of removable denture were recorded. The gender difference of summed values of LCFs for all eight directions (total LCF [TLCF]), the correlation between opposing DLCFs (8 pairs) and between TLCF and height, body weight, handgrip strength, dental state, including the number of residual teeth, the preservation of all anterior teeth and vertical occlusal support categorized with Eichner's classification, and denture wearing were statistically analyzed. TLCF in male was significantly greater than that in female. The DLCFs was large by vertical, oblique and horizontal directions order. No significant correlation between opposing DLCFs was observed in 3 pairs in male and the symmetric DLCFs were not observed from 4 pairs in female. The significant weak correlation between TLCF and height, body weight were observed in male not in female. TLCF was not statistically related to the number of residual teeth or vertical occlusal support and the preservation of all anterior teeth in both genders. In male, TLCF in the subjects with denture wearing was significantly greater than that without denture wearing. We concluded in elderly persons that the altered directional specificity of LCF was observed in comparison with those in healthy children and young adults and that the magnitude of TLCF did not depend on the age and dentate status in healthy elderly persons.

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