title: Dimensional changes of upper airway after rapid maxillary expansion: a prospective cone-beam computed tomography study.
abstract: BACKGROUND
  The aim of this prospective study was to use cone-beam computed tomography to assess the dimensional changes of the upper airway in orthodontic patients with maxillary constriction treated by rapid maxillary expansion.
  
  
  METHODS
  Fourteen orthodontic patients (mean age, 12.9 years; range, 9.7-16 years) were recruited. The patients with posterior crossbite and constricted maxilla were treated with rapid maxillary expansion as the initial part of their comprehensive orthodontic treatments. Before and after rapid maxillary expansion cone-beam computed tomography scans were taken to measure the retropalatal and retroglossal airway changes in terms of volume, and sagittal and cross-sectional areas. The transverse expansions by rapid maxillary expansion were assessed between the midlingual alveolar bone plates at the maxillary first molar and first premolar levels. The measurements of the before and after rapid maxillary expansion scans were compared by using paired t tests with the Bonferroni adjustment for multiple comparisons.
  
  
  RESULTS
  After rapid maxillary expansion, significant and equal amounts of 4.8 mm of expansion were observed at the first molar (P = 0.0000) and the first premolar (P = 0.0000) levels. The width increase at the first premolar level (20.0%) was significantly greater than that at the first molar level (15.0%) (P = 0.035). As the primary outcome variable, the cross-sectional airway measured from the posterior nasal spine to basion level was the only parameter showing a significant increase of 99.4 mm(2) (59.6%) after rapid maxillary expansion (P = 0.0004).
  
  
  CONCLUSIONS
  These results confirm the findings of previous studies of the effect of rapid maxillary expansion on the maxilla. Additionally, we found that only the cross-sectional area of the upper airway at the posterior nasal spine to basion level significantly gains a moderate increase after rapid maxillary expansion.
authors.affiliation: Department of Developmental Science/Orthodontics, School of Dentistry, Marquette University, Milwaukee, WI 53233, USA.
authors.forename: Yoon
authors.initials: Y
authors.lastname: Chang
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Koenig
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Pruszynski
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Bradley
authors.forename: Jose A
authors.initials: JA
authors.lastname: Bosio
authors.forename: Dawei
authors.initials: D
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D019412:Anatomy, Cross-Sectional; D001641:Bicuspid / Q000000981:diagnostic imaging; D002508:Cephalometry / Q000379:methods*; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003724:Dental Arch / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging; D008963:Molar / Q000000981:diagnostic imaging; D009295:Nasal Bone / Q000000981:diagnostic imaging; D009305:Nasopharynx / Q000000981:diagnostic imaging*; D009960:Oropharynx / Q000000981:diagnostic imaging*; D010155:Palatal Expansion Technique; D010159:Palate / Q000473:pathology; D010614:Pharynx / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D014059:Tongue / Q000000981:diagnostic imaging