title: Comparison and reproducibility of 2 regions of reference for maxillary regional registration with cone-beam computed tomography.
abstract: BACKGROUND
  The aims of this study were to evaluate the differences between 2 regions of maxillary voxel-based registration and to test the reproducibility of the registration.
  
  
  METHODS
  Three-dimensional models were built for before-treatment (T1) and after-treatment (T2) based on cone-beam computed tomography images from 16 growing subjects. Landmarks were labeled in all T2 models of the maxilla, and voxel-based registrations were performed independently by 2 observers at 2 times using 2 reference regions. The first region, the maxillary region, included the maxillary bone clipped inferiorly at the dentoalveolar processes, superiorly at the plane passing through the right and left orbitale points, laterally at the zygomatic processes through the orbitale point, and posteriorly at a plane passing through the distal surface of the second molars. In the second region, the palate and infrazygomatic region had different posterior and anterior limits (at the plane passing through the distal aspects of the first molars and the canines, respectively). The differences between the registration regions were measured by comparing the distances between corresponding landmarks in the T2 registered models and comparing the corresponding x, y, and z coordinates from corresponding landmarks. Statistical analysis of the differences between the T2 surface models was performed by evaluating the means and standard deviations of the distances between landmarks and by testing the agreement between coordinates from corresponding landmarks (intraclass correlation coefficient and Bland-Altman method).
  
  
  RESULTS
  The means of the differences between landmarks from the palate and infrazygomatic region to the maxillary region 3-dimensional surface models at T2 for all regions of reference, times of registrations, and observer combinations were smaller than 0.5 mm. The intraclass correlation coefficient and the Bland-Altman plots indicated adequate concordance.
  
  
  CONCLUSIONS
  The 2 regions of regional maxillary registration showed similar results and adequate intraobserver and interobserver reproducibility values.
authors.affiliation: Associate professor, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Brazilian National Counsel of Technological and Scientific Development (CNPq) researcher and postdoctoral fellow, School of Dentistry, University of Michigan, Ann Arbor, Mich. Electronic address: antonioruellas@yahoo.com.br.
authors.forename: Antonio Carlos de Oliveira
authors.initials: AC
authors.lastname: Ruellas
authors.affiliation: Research fellow, Department of Biomedical Sciences and Health, University of Milan, Milan, Italy.
authors.forename: Luis T
authors.initials: LT
authors.lastname: Huanca Ghislanzoni
authors.affiliation: Postgraduate student, Department of Prosthetics, Federal University of Bahia, Salvador, Bahia, Brazil.
authors.forename: Marcelo Regis
authors.initials: MR
authors.lastname: Gomes
authors.affiliation: Postgraduate student, Department of Clinical Sciences and Translational Medicine, University of Rome, Rome, Italy.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Danesi
authors.affiliation: PhD fellow, Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata," Rome, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Lione
authors.affiliation: Assistant professor, Department of Orthodontics, School of Dentistry, University of North Carolina, Chapel Hill, NC.
authors.forename: Tung
authors.initials: T
authors.lastname: Nguyen
authors.affiliation: Thomas M. and Doris Graber Endowed Professor Emeritus, Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, Mich.
authors.forename: James A
authors.initials: JA
authors.lastname: McNamara
authors.affiliation: Professor and department chair, Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata," Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Cozza
authors.affiliation: Research associate, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy; Thomas M. Graber Visiting Scholar, Department of Orthodontics and Pediatric Dentistry, University of Michigan, Ann Arbor, Mich.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Franchi
authors.affiliation: Assistant professor, Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, Mich.
authors.forename: Lucia Helena Soares
authors.initials: LH
authors.lastname: Cevidanes
mesh_terms: D000293:Adolescent; D000539:Alveolar Process / Q000000981:diagnostic imaging; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging; D019412:Anatomy, Cross-Sectional / Q000706:statistics & numerical data; D002508:Cephalometry / Q000706:statistics & numerical data*; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D003481:Cuspid / Q000000981:diagnostic imaging; D057918:Fiducial Markers; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data; D008437:Maxilla / Q000000981:diagnostic imaging*; D008953:Models, Anatomic; D008963:Molar / Q000000981:diagnostic imaging; D015588:Observer Variation; D009915:Orbit / Q000000981:diagnostic imaging; D017289:Orthodontic Appliances, Functional; D010155:Palatal Expansion Technique / Q000295:instrumentation; D010159:Palate / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012189:Retrospective Studies; D015050:Zygoma / Q000000981:diagnostic imaging