title: Correlation of Airway Volume With Orthognathic Surgical Movement Using Cone-Beam Computed Tomography.
abstract: OBJECTIVE
  Orthognathic surgery can induce changes in airway volume. The aim of this study was to determine whether there is a correlation of surgical movement of the maxilla or mandible to airway volume changes.
  
  
  METHODS
  This was a prospective cohort study and the sample was composed of patients undergoing single-jaw orthognathic procedures from 2004 through 2007. Cone-beam computed tomograms were obtained before surgery (T0), immediately after surgery (T1), and at least 6 months after surgery (T2). The airway was segmented from 3-dimensional images and identified as the whole airway, consisting of the naso-, oro-, and hypopharynx. The volumetric percentage of change of the airway between time points was compared and correlated to the surgical movements using paired t test and cubic regression analysis. The level of statistical significance was set at a P value less than or equal to .05.
  
  
  RESULTS
  The sample was composed of 33 patients. Sixteen patients underwent maxillary advancement with mean advancement of 5.4 mm (3 to 8 mm), 13 underwent mandibular advancement with mean advancement of 8.0 mm (5 to 15 mm), and 4 underwent mandibular setback of 4.0 mm. For maxillary advancement at T1, volume percentages of change for the whole airway and the naso-, oro-, and hypopharynx were 18.4 (P ≤ .05), 53.8 (P ≤ .05), 26.3, and 5.5%, respectively, and at T2, the changes were 10.0, 46.7 (P ≤ .05), 6.8, and 1.0%, respectively. For mandibular advancement at T1, volume percentages of change were 34.6 (P ≤ .05), 26.1, 54.1 (P ≤ .05), and 17.4%, respectively, and at T2, the changes were 15.0 (P ≤ .05), -3.7, 23.5 (P ≤ .05), and 12.1%, respectively. There were no meaningful long-term airway changes with mandibular setback.
  
  
  CONCLUSIONS
  The study results suggest that there might be an anatomic limit to pharyngeal airway expansion associated with single-jaw orthognathic surgery.
authors.affiliation: Private Practice, San Carlos, CA; Former Resident, Division of Orthodontics, Department of Orofacial Sciences, University of California, San Francisco, CA.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Chang
authors.affiliation: Private Practice, San Francisco, CA; Former Resident, Division of Orthodontics, Department of Orofacial Sciences, University of California, San Francisco, CA.
authors.forename: Chad
authors.initials: C
authors.lastname: Sears
authors.affiliation: Private Practice, Moraga, CA; Associate Health Science Professor, Division of Orthodontics, Department of Orofacial Sciences, University of California, San Francisco, CA.
authors.forename: John C
authors.initials: JC
authors.lastname: Huang
authors.affiliation: Professor, Division of Orthodontics, Department of Orofacial Sciences, University of California, San Francisco, CA.
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Miller
authors.affiliation: Director, Department of Biostatistics, Biomedical Computer Research Institute, Philadelphia, PA.
authors.forename: Harvey W
authors.initials: HW
authors.lastname: Kushner
authors.affiliation: Clinical Director, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD. Electronic address: Janice.lee@nih.gov.
authors.forename: Janice S
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007013:Hypopharynx / Q000000981:diagnostic imaging; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008334:Mandible / Q000601:surgery; D019186:Mandibular Advancement / Q000379:methods; D063168:Mandibular Osteotomy / Q000379:methods; D008437:Maxilla / Q000601:surgery; D063166:Maxillary Osteotomy / Q000379:methods; D009305:Nasopharynx / Q000000981:diagnostic imaging; D009929:Organ Size; D009960:Oropharynx / Q000000981:diagnostic imaging; D056948:Orthognathic Surgical Procedures / Q000379:methods*; D010614:Pharynx / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D055815:Young Adult