Prosthetic treatment with dentures is often required for the elderly who have reduced swallowing function. Therefore, it is important to understand the relationship between denture-wearing and feeding function from the perspective of swallowing. To clarify changes in bolus transport during feeding in elderly edentulous patients with or without complete dentures. Subjects were 15 elderly edentulous volunteers who were treated with maxillary and mandibular complete dentures. The test food was 10 g of minced agar jelly containing barium sulphate with a particle diameter of 4·0-5·6 mm. Lateral videofluoroscopy was performed to assess the position of the leading edge of the bolus, the bolus volume in each area at swallow onset, bolus transit time and the mandibular position during pharyngeal swallowing. There were significant changes between the bolus transport with and without dentures. Without dentures, the leading edge of the bolus at swallow onset fell from the valleculae area to the hypopharynx, and the bolus volume in the hypopharynx increased. Bolus transit time increased in the oral cavity, valleculae and hypopharynx. The mandibular position shifted anterosuperior direction. The results arose owing to anatomical changes in the oral and pharyngeal structure and the following functional changes: poor food manipulation, poor bolus formation and delayed swallowing reflex. Removing dentures in elderly edentulous individuals influences bolus transport during feeding, resulting in the exacerbation of the reduced swallowing reserve capacity that accompanies ageing, and may increase the risk of dysphagia.

Wearing dentures and dysphagia are common in older individuals; however, it is still unknown how dentures affect oral and pharyngeal swallowing. The purpose of this study was to reveal the effects of wearing and removing dentures on oropharyngeal movements during pharyngeal swallowing in the feeding sequence of solid food. Participants were 25 edentulous volunteers (nine men, 16 women; mean age 76·2 years) who wore complete dentures. The test food was minced agar jelly containing barium sulphate. Subjects were instructed to feed and swallow the test food with or without dentures during observation using videofluorography. We quantitatively evaluated the range, distance and duration of oropharyngeal movements during pharyngeal swallowing. When dentures were absent, the range of mandible and hyoid movements were significantly expanded in the anterosuperior direction, and the range of laryngeal movement was significantly expanded in the anterior direction. Additionally, the posterior pharyngeal wall contraction and upper oesophageal sphincter opening significantly increased. In addition, the distances of the mandible, hyoid and laryngeal movements and the mandibular duration were significantly extended when dentures were absent. No significant differences were observed in the duration of movements of other organs between wearing and removing dentures. The hyoid bone, larynx, posterior pharyngeal wall and upper oesophageal sphincter do not change their duration of movements when dentures were removed but, rather, expand their range of movement. This might be a spatial change of oropharyngeal movement to avoid temporal changes in pharyngeal swallowing when dentures were absent in edentulous older individuals.