title: [A cone-beam computed tomography evaluation of maxillary protraction with repetitive rapid palatal expansions and constrictions].
abstract: OBJECTIVE
  To investigate the effects of maxillary protraction combined with repetitive rapid palatal expansions and constrictions (RPE/C) vs. rapid palatal expansion (RPE) alone using cone-beam computed tomography (CBCT).
  
  
  METHODS
  Twenty four subjects with maxillary retrusion were recruited and block randomized into either the control group (n = 12) or the RPE/C (n = 12) group.
  
  
  METHODS
  facemask protraction after RPE. RPE/C group: facemask protraction after RPE/C. 3D reconstruction, landmarks identifying, superimposition and cephalometric analysis were performed to compare the pre-treatment and post- treatment CBCT images.
  
  
  RESULTS
  One subject in the RPE/C group was lost to follow up during the treatment. Maxilla moved forward [(2.5±1.0) mm] after maxillary protraction with RPE/C, which was significantly greater than that in the control group [(1.6±0.8) mm] (P < 0.05). The distance of basion to subspinale (Ba-A) increased [(3.1±1.0) mm] in the RPE/C group, which was significantly greater than that in the control group [(2.2 ± 0.9) mm] (P < 0.05). The amount of forward movement of upper first molars was significantly greater in the RPE/C group (P < 0.05).
  
  
  CONCLUSIONS
  Maxillary protraction with RPE/C might positively affect the forward movement of maxilla compared with the RPE alone protocol with the early treatment of maxillary retrusion patients.
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Weitao
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China. Email: hkushark@hotmail.com.
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Xuedong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Danqing
authors.initials: D
authors.lastname: He
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Yanheng
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D002508:Cephalometry; D054893:Cone-Beam Computed Tomography; D003250:Constriction; D005115:Extraoral Traction Appliances; D006801:Humans; D008313:Malocclusion, Angle Class III / Q000628:therapy*; D008437:Maxilla; D008963:Molar; D010155:Palatal Expansion Technique