title: Three-dimensional changes of the hyoid bone and airway volumes related to its relationship with horizontal anatomic planes after bimaxillary surgery in skeletal Class III patients.
abstract: OBJECTIVE
  To evaluate longitudinal changes of the hyoid bone position and pharyngeal airway space after bimaxillary surgery in mandibular prognathism patients.
  
  
  METHODS
  Cone-beam computed tomography scans were taken for 25 mandibular prognathism patients before surgery (T0), 2 months after surgery (T1), and 6 months after surgery (T2). The positional displacement of the hyoid bone was assessed using the coordinates at T0, T1, and T2. Additionally, the volume of each subject's pharyngeal airway was measured.
  
  
  RESULTS
  The mean amount of posterior maxilla impaction was 3.76 ± 1.33 mm as the palatal plane rotated 2.04° ± 2.28° in a clockwise direction as a result of bimaxillary surgery. The hyoid bone moved backward (P < .05, P < .001) and downward (P > .05, P < .05) at 2 months and 6 months after surgery, while the total volume of the pharyngeal airway significantly decreased at the same time points (P < .001, P < .001). There was significant relationship between the changes of the hyoid bone position and airway volume at 2 months after surgery (P < .05). The change of the palatal plane angle was positively correlated to the decrease in the total airway volume (P < .001).
  
  
  CONCLUSIONS
  The null hypothesis was rejected. The hyoid bone moved inferoposteriorly, and the pharyngeal airway volume decreased for up to 6 months after bimaxillary surgery. The decrease in the pharyngeal airway volume was correlated to the changes in the palatal plane inclination and the positional change of the hyoid bone.
authors: Department of Orthodontics, Kangdong Sacred Heart Hospital, Hallym University Medical Center, Seoul, Korea.
authors: Min-Ah
authors: MA
authors: Kim
authors: Bo-Ram
authors: BR
authors: Kim
authors: Jin-Young
authors: JY
authors: Choi
authors: Jong-Kuk
authors: JK
authors: Youn
authors: Yoon-Ji R
authors: YJ
authors: Kim
authors: Yang-Ho
authors: YH
authors: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry / Q000379:methods; D054893:Cone-Beam Computed Tomography / Q000379:methods; D004825:Epiglottis / Q000000981:diagnostic imaging; D005260:Female; D005500:Follow-Up Studies; D063172:Genioplasty / Q000379:methods; D006801:Humans; D006928:Hyoid Bone / Q000000981:diagnostic imaging*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008137:Longitudinal Studies; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery*; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery*; D008437:Maxilla / Q000000981:diagnostic imaging / Q000601:surgery*; D008875:Middle Aged; D009295:Nasal Bone / Q000000981:diagnostic imaging; D009971:Orthodontics, Corrective / Q000295:instrumentation; D056948:Orthognathic Surgical Procedures / Q000379:methods*; D019340:Osteotomy, Le Fort / Q000379:methods; D059229:Osteotomy, Sagittal Split Ramus / Q000379:methods; D010159:Palate / Q000000981:diagnostic imaging; D010160:Palate, Soft / Q000000981:diagnostic imaging; D010614:Pharynx / Q000000981:diagnostic imaging*; D011378:Prognathism / Q000601:surgery; D012399:Rotation; D055815:Young Adult