In this study, we investigated the association of results obtained with Eating Assessment Tool-10 (EAT-10) and Repetitive Saliva Swallowing Test (RSST) with the oral hygiene, oral function, and nutritional status of elderly individuals. A total of 90 subjects (21 males, 69 females, average age: 86.0±7.2 years) were enrolled. We assessed the cleanliness of tooth surfaces as oral hygiene, mouth-opening capacity as the masticatory function, and Short-form Mini Nutritional Assessment (MNA-SF) findings as the nutritional status, as well as subjective symptoms related to swallowing. Associations between subjects with and without the risk of developing dysphagia were analyzed based on EAT-10 and RSST scores, while path analysis was also conducted. There were significant correlations of dysphagia assessed by EAT-10 with tooth surface cleanliness and the mouth-opening capacity, as well as the subjective symptoms of hard to swallow and choking. In addition, significant correlations of dysphagia assessed by RSST with the mouth-opening capacity, tongue movement, and number of chewable foods, as well as the subjective symptoms of hard to swallow and choking shown in MNA-SF findings were noted. Path analysis results indicated a weak association between EAT-10 and RSST, while there were significant paths from EAT-10 to tooth surface cleanliness and stains on the tongue, as well as the subjective symptoms of hard to swallow and choking, and significant paths or trends from RSST to tongue movement, number of chewable foods, and MNA-SF findings. The present results indicate that EAT-10 is influenced by factors related to oral hygiene and subjective symptoms, while factors influencing RSST are related to the masticatory function and nutritional status. It is suggested that findings obtained by screening with EAT-10 are correlated with those with RSST, although the specific characteristics are different.

 Hinokitiol (HNK) is a well-known antimicrobial and antifungal agent, and is widely used in various formulations including tooth pastes, mouth rinses, aromatics, cosmetics, and food. There is limited information on the immunobiological activity of HNK. In the present study, we investigated the effects of interanasally administered HNK on salivary secretory-IgA antibody (SIgA Ab) secretion in mice. BALB/c (8 weeks old) mice were given 50 μg of HNK four times at weekly intervals (Days 0, 7, 14, and 21) via the nasal route. Saliva samples were collected prior to (−0 hour) and after (0.5, 1.5, 3, and 6 hours) the nasal administration of HNK on respective days, and the levels of salivary SIgA Ab were determined by ELISA. Furthermore, the numbers of SIgA Ab-producing cells (SIgA AFCs) in submandibular glands (SMG) were examined by ELISPOT, and proliferation responses of IgA⁺ B cells were measured by MTT assays based on the same schedule on Day 21.

 On Days 0, 7, 14, and 21, the maximum level of SIgA Ab secretion in saliva occurred at 1.5 hours after the nasal administration of HNK. Interestingly, the number of doses of HNK and quantities of SIgA secretion showed a positive correlation. On Day 21, there were no significant differences between the number of SMG IgA AFCs prior to and after (0.5, 1.5, 3, and 6 hours) the nasal administration of HNK. However, significantly increased levels of IgA AFCs due to promotion of their proliferative activity were noted 0.5 and 1.5 hours after the nasal administration of HNK. Our results suggest that HNK has an impact on salivary SIgA Ab secretion immediately after nasal administration via elevating the proliferative activity of SMG IgA AFCs.

 Tongue pressure is the force produced by contact between the anterior part of the hard palate and tongue, which is composed chiefly of muscle tissue. Tongue pressure is one of the objective indicators of oral function. Low whole-body skeletal muscle mass has been reported to be associated with functional impairment and physical disability. However, little is known about the relationship between whole-body skeletal muscle mass and oral function. This study aimed to elucidate the relationship between whole-body skeletal muscle mass and tongue pressure in individuals aged ≥75 years old requiring home-based support.

 This study included 64 individuals aged ≥75 years (average age = 86.4 years; 18 men and 46 women) who used home-based care support covered by long-term care insurance. Tongue pressure was measured using a tongue pressure measurement device. In addition, limb skeletal muscle mass was measured by a body composition analyzer. Subsequently, the skeletal muscle index (SMI) was calculated by dividing the absolute limb skeletal muscle mass by the height in meters squared. Then, the association between tongue pressure and SMI was estimated by robust regression analysis. Variables that showed a significant correlation with tongue pressure in univariate analysis were included as potential confounders in the multivariable model.

 Univariate analysis showed a significant positive correlation between SMI and tongue pressure. This remained significant after adjusting for potential confounders (regression coefficient=3.6; 95% confidence interval=1.6–5.5; p<0.01).

 In conclusion, this study demonstrated a significant positive correlation between whole-body skeletal muscle mass and tongue pressure in individuals aged ≥75 years old requiring home-based care support.

Abstract in Japaneses

Abstract in Japaneses