title: Use of shape correspondence analysis to quantify skeletal changes associated with bone-anchored Class III correction.
abstract: OBJECTIVE
  To evaluate the three-dimensional (3D) skeletal changes in the mandibles of Class III patients treated with bone-anchored maxillary protraction using shape correspondence analysis.
  
  
  METHODS
  Twenty-five consecutive patients with skeletal Class III who were between the ages of 9 and 13 years (mean age, 11.10 ± 1.1 years) were treated using Class III intermaxillary elastics and bilateral miniplates (two in the infrazygomatic crests of the maxilla and two in the anterior mandible). Cone-beam computed tomography (CBCT) was performed for each patient before initial loading (T1) and at 1 year out (T2). From the CBCT scans, 3D models were generated, registered on the anterior cranial base, and analyzed using 3D linear distances and vectors between corresponding point-based surfaces.
  
  
  RESULTS
  Bone-anchored traction produced anteroposterior and vertical skeletal changes in the mandible. The novel application of Shape correspondence analysis showed vectors of mean (± standard deviation) distal displacement of the posterior ramus of 3.6 ± 1.4 mm, while the chin displaced backward by 0.5 ± 3.92 mm. The lower border of the mandible at the menton region was displaced downward by 2.6 ± 1.2 mm, and the lower border at the gonial region moved downward by 3.6 ± 1.4 mm. There was a downward and backward displacement around the gonial region with a mean closure of the gonial angle by 2.1°. The condyles were displaced distally by a mean of 2.6 ± 1.5 mm, and there were three distinct patterns for displacement: 44% backward, 40% backward and downward, and 16% backward and upward.
  
  
  CONCLUSIONS
  This treatment approach induces favorable control of the mandibular growth pattern and can be used to treat patients with components of mandibular prognathism.
authors.affiliation: a  Assistant Professor, Department of Orthodontics, University of North Carolina, Chapel Hill, NC.
authors.forename: Tung
authors.initials: T
authors.lastname: Nguyen
authors.forename: Lucia
authors.initials: L
authors.lastname: Cevidanes
authors.forename: Beatriz
authors.initials: B
authors.lastname: Paniagua
authors.forename: Hongtu
authors.initials: H
authors.lastname: Zhu
authors.forename: Leonardo
authors.initials: L
authors.lastname: Koerich
authors.forename: Hugo
authors.initials: H
authors.lastname: De Clerck
mesh_terms: D000293:Adolescent; D001860:Bone Plates; D002508:Cephalometry / Q000379:methods*; D002648:Child; D002680:Chin / Q000473:pathology; D054893:Cone-Beam Computed Tomography / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008313:Malocclusion, Angle Class III / Q000628:therapy*; D008334:Mandible / Q000254:growth & development / Q000473:pathology*; D008335:Mandibular Condyle / Q000473:pathology; D008437:Maxilla / Q000473:pathology; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation* / Q000379:methods; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D019291:Skull Base / Q000473:pathology; D014716:Vertical Dimension