title: Effects of mandibular advancement on supine airway size in normal subjects during sleep.
abstract: OBJECTIVE
  To examine changes in the upper-airway dimension and its surrounding structures induced by mandibular advancement during sleep.
  
  
  METHODS
  Eleven nonapneic adult males participated in the study. A set of supine lateral cephalograms was taken for each subject at the end of expiration during stage 1 and 2 non-rapid-eye-movement sleep with and without a Klearway appliance (Great Lakes Orthodontics, NY, USA), which was adjusted to 67% of the maximum protrusion position. The Wilcoxon signed-rank test was used to compare changes in the anteroposterior width of the upper airway and the positions of the hyoid bone and third cervical vertebra with and without the appliance.
  
  
  METHODS
  N/A.
  
  
  METHODS
  N/A.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  The amount of jaw opening was significantly increased by wearing the titratable oral appliance, and the mandibular symphysis moved backward. The sagittal dimension of the superior pharyngeal airway was significantly increased; however, no significant changes were found in the middle and inferior pharyngeal airway. Significant posterior displacement of the hyoid bone and third cervical vertebra was seen. Moreover, significant inferior displacement of the hyoid bone was also seen. The relationship among the mandibular symphysis, the hyoid bone, and the third cervical vertebra remained constant.
  
  
  CONCLUSIONS
  Mandibular advancement significantly increases the size of the upper airway in the velopharynx and results in posteroinferior displacement of the hyoid bone and posterior displacement of the third cervical vertebra during sleep.
authors.affiliation: Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, Japan. s-hiyama@syd.odn.ne.jp
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Hiyama
authors.forename: Satoru
authors.initials: S
authors.lastname: Tsuiki
authors.forename: Takashi
authors.initials: T
authors.lastname: Ono
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kuroda
authors.forename: Kimie
authors.initials: K
authors.lastname: Ohyama
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000517:prevention & control*; D015992:Body Mass Index; D006801:Humans; D008297:Male; D019186:Mandibular Advancement / Q000379:methods*; D012123:Pulmonary Ventilation; D012890:Sleep; D012894:Sleep Stages / Q000502:physiology; D016683:Supine Position