title: Evaluation of upper airway dimensional changes and hyoid position following mandibular advancement in patients with skeletal class II malocclusion.
abstract: BACKGROUND
  Class II skeletal malocclusion due to mandibular deficiency is considered a risk factor for sleep disorders due to oropharyngeal airway deficiencies. In view of the above, a prospective interventional study was undertaken to evaluate upper airway dimensional changes and position of hyoid bone by comparing pretreatment and posttreatment lateral cephalograms. The objective also included the establishment of the ratio of mandibular advancement to increase in airway dimensions.
  
  
  METHODS
  Pretreatment and posttreatment lateral cephalograms of 20 adults (13 females and 7 males) with skeletal class II malocclusion treated by combined orthodontics and bilateral sagittal split ramus osteotomy was evaluated for changes in posterior airway space (PAS), superior airway space (SAS), minimum airway space (MAS), hyoid bone position (MP-H), effective mandibular length (Co-Gn), mandibular corpus length (Go-Pg), and pogonion position (N perpendicular-Pg). The cephalograms were manually traced by a single operator and the data analyzed using MINITAB 13.2 version software.
  
  
  RESULTS
  There was a statistically highly significant (P = 0.0001) increase in PAS, SAS, MP-H, Co-Gn, and Go-Pg. The mean ratio of mandibular advancement to increase PAS, SAS, and MAS was 1:0.35, 1:0.34, and 1:0.24, respectively. Hyoid bone moved superiorly and in an anterior direction by 2.1 ± 2.8 mm and was found to be statistically highly significant (P = 0.0001).
  
  
  CONCLUSIONS
  The study showed an overall increase in airway dimension and improvement in hyoid position. Thus, the procedure may be considered beneficial in reducing upper airway collapsibility and preventing sleep disorders due to oropharyngeal airway deficiencies in skeletal class II malocclusion.
authors.affiliation: Department of Dental Surgery, Armed Forces Medical College, Pune, India. colnksahoo@gmail.com
authors.forename: Nanda Kishore
authors.initials: NK
authors.lastname: Sahoo
authors.forename: Balakrishnan
authors.initials: B
authors.lastname: Jayan
authors.forename: N
authors.initials: N
authors.lastname: Ramakrishna
authors.forename: Sukbir Singh
authors.initials: SS
authors.lastname: Chopra
authors.forename: Gagandeep
authors.initials: G
authors.lastname: Kochar
mesh_terms: D000328:Adult; D002508:Cephalometry; D005260:Female; D006801:Humans; D006928:Hyoid Bone; D008297:Male; D008312:Malocclusion, Angle Class II / Q000000981:diagnostic imaging* / Q000601:surgery*; D019186:Mandibular Advancement; D059229:Osteotomy, Sagittal Split Ramus; D010614:Pharynx / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011859:Radiography; D016896:Treatment Outcome