title: Long-term changes of hyoid bone position and pharyngeal airway size following mandibular setback by sagittal split ramus osteotomy.
abstract: BACKGROUND
  The purpose of this study was to determine long-term changes in hyoid bone position and pharyngeal airway size after mandibular setback osteotomies.
  
  
  METHODS
  Serial cephalograms of 12 patients who underwent mandibular setback surgery were evaluated preoperatively, at 1 week, 6 months, and 14 months postoperatively, and finally after an average of 12 years.
  
  
  RESULTS
  A mean setback of 5.6 mm was associated with a posterior and inferior movement of the hyoid bone. At long-term follow-up, the hyoid bone adapted horizontally to a position about 1.6 mm more posterior than its preoperative location. Immediately after surgery, the length of suprahyoid muscles correlated significantly with skeletal movements: suprahyoid muscles shortened by 4 mm but started lengthening after 1 year. Thereafter, it tended to correlate with the change of hyoid bone position rather than with skeletal relapse. Following the initial decrease after surgery, the size of the lower pharyngeal airway remained almost unchanged. The upper and middle pharyngeal airway sizes continued to decrease over the postoperative period of 12 years, and ultimately were smaller than their preoperative sizes by about 1.5 and 3 mm, respectively.
authors.affiliation: Department of Cranio-Maxillofacial Surgery, University of Berne, Switzerland. nicole.eggensperger@insel.ch
authors.forename: Nicole
authors.initials: N
authors.lastname: Eggensperger
authors.forename: Wenko
authors.initials: W
authors.lastname: Smolka
authors.forename: Tateyuki
authors.initials: T
authors.lastname: Iizuka
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000209:etiology*; D002508:Cephalometry; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006928:Hyoid Bone / Q000503:physiopathology*; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery*; D008334:Mandible / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000601:surgery*; D008875:Middle Aged; D009334:Neck Muscles / Q000503:physiopathology; D019647:Oral Surgical Procedures / Q000009:adverse effects*; D010027:Osteotomy / Q000009:adverse effects; D010614:Pharynx / Q000473:pathology*; D011378:Prognathism / Q000601:surgery; D011859:Radiography; D012008:Recurrence; D018709:Statistics, Nonparametric