Impacts of Complete Dentures on Oropharyngeal Movements During Bolus Processing

Objectives: Coordinated movements of the oral cavity and the pharynx are necessary for smooth feeding and swallowing in elderly individuals who often needed dentures. Thus, it is important to clarify the relationships between denture-wearing and swallowing as a sequential feeding movement. Previous researches revealed that removing dentures might affect bolus formation, bolus transportation and swallowing in the oral cavity and the pharynx, but the detail effects are still unclear. The objective of this study was to clarify effects of denture-wearing on oral and pharyngeal movements during bolus processing before swallowing.

Methods: Participants were 25 edentulous elderly volunteers who has their complete dentures and provided written consents. The study protocols were approved by the ethics committee of the Iwate Medical University School of Dentistry (No. 01150). The test food was minced agar jelly containing barium sulfate. Subjects were instructed to feed and swallow the test food with or without dentures during observation using lateral videofluorography. We quantitatively and qualitatively evaluated movements of mandible, hyoid bone, lips and tongue during food bolus processing before swallowing. Wilcoxon signed-rank test and Chi-squared test were used for the statistical analysis.

Results: The range of mandibular and hyoid movements were significantly expanded in anterior-superior direction when dentures were absent (p<0.05). The movement of lips and tongue were significantly expanded and become unstable when dentures were absent (p<0.05). Oral and pharyngeal movements during food bolus processing before swallowing were expanded to compensate the absence of dentures in the oral cavity.
Conclusions: Present results suggested that wearing dentures contributed to stable oropharyngeal movement during bolus processing before swallowing from the perspective of spatial motion analysis. Removing dentures lost the oral anatomical structure and occlusal support, leading to extra oropharyngeal movements to compensate declined bolus formation ability.