Background. Although age-related changes resulting in slowing of the swallowing reflex and a decline in the neuromuscular control system have been reported, there have been few reports on swallowing function in dentate elderly persons. The purpose of this study was to clarify the primary influence of aging on swallowing in healthy dentate elderly persons older than 80 years who have more than 20 teeth. Methods. Dentate elderly persons (12 male, 7 female; mean age: 81.2 years) and dentate young participants (9 male, 5 female; mean age: 26.8 years) as a control group participated voluntarily. Participants reported no clinical symptoms relating to dysphagia, neurologic impairments, or degenerative diseases, and were asked to swallow 10 ml of barium sulfate solution (10% w/v) three times. Functional swallowing was recorded on 35 mm cinefilm at 30 frames per second with a digital subtraction angiography system. Lateral images of cinefluorography of seated participants' mouth, pharynx, and larynx were obtained. Visual image analysis for qualitative and quantitative evaluation was made with a cine projector. Results. No participants exhibited aspiration during three trials. Occurrence and frequencies of piecemeal deglutition, premature loss of liquid, oral and pharyngeal residues, and laryngeal penetration were significantly greater in dentate elderly persons (p <.05) than in the dentate young participants. Oral transit time, pharyngeal delay time, and pharyngeal transit time in dentate elderly persons were prolonged significantly compared with those in dentate young participants (p <.01). Conclusion. Physiological swallowing functions deteriorate even in healthy dentate elderly persons. This deterioration may be explained primarily by the influence of aging on swallowing.

Maintenance of natural dentition and/or prosthodontic rehabilitation is necessary for good masticatory function. Although other factors such as physical and oral functions are also important for masticatory performance, only a few studies have evaluated their roles. The aim of the current study was to assess factors associated with masticatory performance among elderly individuals, while maintaining and/or reconstructing all occlusal support areas. The present study was designed and implemented as a cross-sectional study, involving a total of 262 participants (mean age: 74.2±5.9years) who participated in the Kyoto Elders Physical Fitness Measurement Research Project. Individuals with partial or complete edentulousness who did not use dentures were excluded from the study. The predictor variables included physical status (i.e., age, gender, body-mass index, and grip strength), oral conditions (i.e., number of present teeth, temporomandibular joint noise, and denture wearer), and oral functions (i.e., maximum voluntary occlusal force; occlusal contact area; cheek pressure; oral diadochokinesis test /pa/, /ta/, /ka/; and maximum voluntary tongue pressure). The variable outcome was masticatory performance. These variables among the participants using univariate and multivariate analyses were compared. Grip strength, number of present teeth, maximum voluntary occlusal force, occlusal contact area, oral diadochokinesis /ka/ /ta/, and maximum voluntary tongue pressure were significant factors for masticatory performance. Stepwise regression analysis showed that grip strength, maximum voluntary occlusal force, and diadochokinesis /ta/ significantly affected masticatory performance. Masticatory performance was closely associated with grip strength, maximum voluntary occlusal force, and diadochokinesis /ta/ among healthy elderly participants.