This study was performed to ascertain the relationships between oral motor functions, such as those of the tongue and lips, and age in the community-dwelling elderly, as well as to investigate the effects of these factors on masticatory performance. The subjects were 268 healthy elderly Japanese living in Kyoto. They were divided into four age groups and further classified into the following two groups by the presence or absence of posterior occlusal support: Eichner A or B1-B3 (group A), and Eichner B4 or C (group B). They were wearing removable or fixed dentures if they had missing teeth. Oral function evaluation items included (1) masticatory performance and (2) oral motor skills. Significant differences were noted among the age groups in tongue pressure within group A (P < 0.01) and group B (P < 0.05), and in the number of repetitions of the syllables /ta/ and /ka/ in group B (/ta/: P < 0.05, /ka/; P < 0.01). The number of natural teeth (beta = 0.463, P < 0.001) in group A and tongue pressure (beta = 0.436, P < 0.001) in group B were the only predictors of masticatory performance when the data were analyzed by multiple regression analysis. The tongue may compensate for the missing teeth in masticatory performance of those elderly who have lost their natural teeth. The results of this study highlight the importance of tongue function in masticatory performance.

The purpose of the present study was to examine what dysphagic signs identified by videoendoscopy (VE) could predict the incidence of pneumonia and body weight loss in elderly patients living in nursing homes. This study was performed at six nursing care facilities in Japan from March 2007 to February 2009. The 148 subjects (85·1 ± 8·0 years, male/female: 43/105) were evaluated for their feeding and swallowing movements by clinical and VE examinations during the consumption of a regular meal. The VE examination items included the existence/absence of pharyngeal residue, laryngeal penetration, and aspiration of food and saliva. The patients were followed-up for 3 months with individualized feeding therapy based on the results of the clinical/VE examination at baseline, and the incidence of pneumonia was examined as the primary outcome. In patients without pneumonia, the body weight change was also measured as a secondary outcome. The risk factors for pneumonia and body weight loss (of 3% or more) were identified among the clinical/VE examination items by a Cox proportional hazard analysis. Even with elaborative feeding therapy, 12 (8·1%) of the 148 patients developed pneumonia during the 3 months follow-up period. The existence of signs of 'silent aspiration of saliva' or 'aspiration of saliva' detected by VE examination was a significant risk factor for both pneumonia and a body weight loss of 3% or more. This study shows that 'aspiration of saliva' detected by VE is a significant risk factor for both pneumonia and body weight loss in elderly patients living in nursing homes.

In mammals, the midportion of the soft tissue of Meckel's cartilage at the degenerating stage forms a ligament known as the sphenomandibular ligament. To clarify the mechanism of formation of this ligament by Meckel's cartilage in mouse, we examined the effects of epidermal growth factor (EGF) on the chondrocytes in terms of the proliferation and differentiation of cells and calcification of the matrix in vivo and in vitro. The effects of EGF were examined by immunohistochemical staining, with EGF-soaked beads, by electron microscopy, and by general histochemical analysis of proteoglycans and calcification. Analysis of labeling with bromodeoxyuridine (BrdU) and the rate of cell growth revealed that EGF enhanced DNA synthesis and the proliferation of Meckel's chondrocytes. Histological findings in organ culture and in cell culture, with and without the application of EGF-soaked beads, revealed that EGF inhibited the differentiation of cells to chondrocytes and induced phenotypic changes in fibroblastic cells. The inhibition of alkaline phosphatase activity that resulted from exposure to EGF was accompanied by prolonged calcification of the matrix. Whole-mount staining revealed that subcutaneous injection of EGF enhanced the disappearance of Meckel's cartilage. Our results suggest a possible mechanism whereby the midportion of Meckel's cartilage remains uncalcified and is rapidly transformed into the sphenomandibular ligament.

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