title: Enhanced increase in pharyngeal airway size in Japanese class II children following a 1-year treatment with an activator appliance.
abstract: OBJECTIVE
  The aim of this study was to assess the upper airway soft-tissue structures in Class IIJapanese children following activator treatment by means of cephalometric analysis.
  
  
  METHODS
  A lateral cephalometric radiograph was taken of each patient at Ti (prior to the placement of the activator; mean age: 11 years, 5 months) and T2 (after 1 year of activator treatment; mean age: 12 years, 5 months). Tracings of the lateral cephalometric radiographs were made on acetate paper, and several soft-tissue points and contours of the tongue, soft palate, hyoid, and pharynx were digitised.
  
  
  RESULTS
  The sizes of the oropharynx and hypopharynx were significantly smaller in Class II patients than in Class I patients. Moreover, significant differences were observed in the sizes of the tongue and soft palate between Class I and II patients at the age of 12. In terms of the ratio of change relative to the initial values between the 2 skeletal patterns, the width and dimension of the pharyngeal airway in Class II patients showed considerable increases after activator use.
  
  
  CONCLUSIONS
  The pharyngeal airway soft tissue structures of Class I patients using the activator exceeded normal growth after 1 year. This finding suggests that correction ofskeletal Class II discrepancies by the activator in orthodontic treatment could reduce the risk of respiratory problems, such as severe snoring, obstructive sleep apnoea, and excessive daytime sleepiness in the future.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Horihata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueda
authors.forename: Myongsun
authors.initials: M
authors.lastname: Koh
authors.forename: Genki
authors.initials: G
authors.lastname: Watanabe
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanne
mesh_terms: D000202:Activator Appliances; D019412:Anatomy, Cross-Sectional / Q000379:methods; D002508:Cephalometry / Q000379:methods; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006928:Hyoid Bone / Q000473:pathology; D007013:Hypopharynx / Q000473:pathology; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007564:Japan; D008297:Male; D008311:Malocclusion, Angle Class I / Q000473:pathology / Q000628:therapy; D008312:Malocclusion, Angle Class II / Q000473:pathology / Q000628:therapy*; D008334:Mandible / Q000473:pathology; D008437:Maxilla / Q000473:pathology; D009305:Nasopharynx / Q000473:pathology; D009960:Oropharynx / Q000473:pathology; D010160:Palate, Soft / Q000473:pathology; D010614:Pharynx / Q000254:growth & development / Q000473:pathology*; D014059:Tongue / Q000473:pathology; D016896:Treatment Outcome