Wearing complete dentures is associated with changes in the three-dimensional shape of the oropharynx in edentulous older people that affect swallowing.
OBJECTIVE
To investigate the effects of wearing complete dentures on pharyngeal shape for swallowing in edentulous older people.


BACKGROUND
In the absence of complete dentures, edentulous older people often lose the occlusal support necessary to position the mandible, which leads to an anterosuperior shift of the mandible during swallowing. This may result in pharyngeal shape changes effecting swallowing function in older people. However, the details of this phenomenon are currently unclear.


METHODS
Participants were 17 older edentulous volunteers. Cone-beam computed tomography imaging was performed with the participant in the seated position and wearing (i) both maxillary and mandibular dentures, (ii) maxillary dentures only and (iii) no dentures. During imaging, participants were instructed to keep their mouth closed to the mandibular position determined in advance during swallowing for each denture-wearing condition. The volume, height and average cross-sectional area of the velopharynx and oropharynx were measured, and the positions of the epiglottis and mandible were recorded.


RESULTS
While the vertical height of the oral cavity and pharynx significantly decreased, the volume and average cross-sectional area of the oropharynx significantly increased when dentures were not worn (p < 0.01). The absence of dentures caused an anterosuperior shift of the mandible when swallowing and drew the epiglottis forward, resulting in expansion of the oropharynx where the tongue base forms the anterior wall.


CONCLUSIONS
The absence of dentures results in anatomical changes in oropharyngeal shape that may exacerbate the pharyngeal expansion caused by ageing and reduce the swallowing reserve.
Department of Prosthodontics and Oral Implantology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan. furuyajunichi@gmail.com.
Junichi
J
Furuya
Department of Prosthodontics and Oral Implantology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
Yasushi
Y
Tamada
Department of Prosthodontics and Oral Implantology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
Tomohide
T
Sato
Department of Prosthodontics and Oral Implantology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
Atsushi
A
Hara
Department of Prosthodontics and Oral Implantology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
Taro
T
Nomura
Department of Prosthodontics and Oral Implantology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
Takuya
T
Kobayashi
Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, MA, USA.
Maiko
M
Sakai
Department of Prosthodontics and Oral Implantology, School of Dentistry, Iwate Medical University, Morioka, Iwate, Japan.
Hisatomo
H
Kondo
D054893:Cone-Beam Computed Tomography; D003679:Deglutition / Q000502:physiology*; D003824:Denture, Complete / Q000592:standards*; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology; D009066:Mouth, Edentulous / Q000473:pathology*; D009960:Oropharynx / Q000033:anatomy & histology*
centric relation; complete dentures; computed tomography; occlusal vertical dimension; pharynx; swallowing