title: Three-Dimensional Evaluation of the Upper Airway Morphological Changes in Growing Patients with Skeletal Class III Malocclusion Treated by Protraction Headgear and Rapid Palatal Expansion: A Comparative Research.
abstract: OBJECTIVE
  The aim of this study was to evaluate the morphological changes of upper airway after protraction headgear and rapid maxillary expansion (PE) treatment in growing patients with Class III malocclusion and maxillary skeletal deficiency compared with untreated Class III patients by cone-beam computed tomography (CBCT).
  
  
  METHODS
  Thirty growing patients who have completed PE therapy were included in PE group. The control group (n = 30) was selected from the growing untreated patients with the same diagnosis. The CBCT scans of the pre-treatment (T1) and post-treatment (T2) of PE group and the control group were collected. Reconstruction and registration of the 3D models of T1 and T2 were completed. By comparing the data obtained from T1, T2 and control group, the morphological changes of the upper airway during the PE treatment were evaluated.
  
  
  RESULTS
  Comparing with the data from T1 group, the subspinale (A) of maxilla and the upper incisor (UI) of the T2 group were moved in the anterior direction. The gnathion (Gn) of mandible was moved in the posterior-inferior direction. The displacement of the hyoid bone as well as the length and width of dental arch showed significant difference. The volume and mean cross-sectional area of nasopharynx, velopharynx and glossopharynx region showed significant difference. The largest anteroposterior/the largest lateral (AP/LR) ratios of the velopharynx and glossopharynx were increased, but the AP/LR ratio of the hypopharynx was decreased. In addition, the length and width of the maxillary dental arch, the displacement of the hyoid bone, the volume of nasopharynx and velopharynx, and the AP/LR ratio of the hypopharynx and velopharynx showed significant difference between the data from control and T2 group.
  
  
  CONCLUSIONS
  The PE treatment of Class III malocclusion with maxillary skeletal hypoplasia leads to a significant increase in the volume of nasopharynx and velopharynx.
authors.affiliation: Department of Orthodontics, School of Dentistry, Shandong University, Jinan, China; Department of Orthodontics, Shandong Provincial Key Laboratory of Oral Biomedicine, School of Dentistry, Shandong University, Jinan, China; Department of Stomatology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Xueling
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Orthodontics, School of Dentistry, Shandong University, Jinan, China; Department of Orthodontics, Shandong Provincial Key Laboratory of Oral Biomedicine, School of Dentistry, Shandong University, Jinan, China.
authors.forename: Dongxu
authors.initials: D
authors.lastname: Liu
authors.affiliation: Medical Research Center, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, China.
authors.forename: Ju
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Stomatology, The Chinese People's Liberation Army 88 Hospital, Taian, China.
authors.forename: Zizhong
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Stomatology, Traditional Chinese Medical Hospital of Shandong Province, Jinan, China.
authors.forename: Yongtao
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Orthodontics, Shandong Provincial Key Laboratory of Oral Biomedicine, School of Dentistry, Shandong University, Jinan, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Orthodontics, School of Dentistry, Shandong University, Jinan, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Orthodontics, School of Dentistry, Shandong University, Jinan, China; Department of Stomatology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Guo
authors.affiliation: Department of Orthodontics, School of Dentistry, Shandong University, Jinan, China; Department of Stomatology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Stomatology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Shijie
authors.initials: S
authors.lastname: Zhang
mesh_terms: D002648:Child; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D008297:Male; D008313:Malocclusion, Angle Class III / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000628:therapy*; D008437:Maxilla / Q000002:abnormalities* / Q000000981:diagnostic imaging; D009305:Nasopharynx / Q000000981:diagnostic imaging / Q000502:physiology; D009967:Orthodontic Appliances; D010155:Palatal Expansion Technique; D011857:Radiographic Image Interpretation, Computer-Assisted; D016896:Treatment Outcome