title: Newly defined landmarks for a three-dimensionally based cephalometric analysis: a retrospective cone-beam computed tomography scan review.
abstract: OBJECTIVE
  To identify two novel three-dimensional (3D) cephalometric landmarks and create a novel three-dimensionally based anteroposterior skeletal measurement that can be compared with traditional two-dimensional (2D) cephalometric measurements in patients with Class I and Class II skeletal patterns.
  
  
  METHODS
  Full head cone-beam computed tomography (CBCT) scans of 100 patients with all first molars in occlusion were obtained from a private practice. InvivoDental 3D (version 5.1.6, Anatomage, San Jose, Calif) was used to analyze the CBCT scans in the sagittal and axial planes to create new landmarks and a linear 3D analysis (M measurement) based on maxillary and mandibular centroids. Independent samples t-test was used to compare the mean M measurement to traditional 2D cephalometric measurements, ANB and APDI. Interexaminer and intraexaminer reliability were evaluated using 2D and 3D scatterplots.
  
  
  RESULTS
  The M measurement, ANB, and APDI could statistically differentiate between patients with Class I and Class II skeletal patterns (P < .001). The M measurement exhibited a correlation coefficient (r) of -0.79 and 0.88 with APDI and ANB, respectively.
  
  
  CONCLUSIONS
  The overall centroid landmarks and the M measurement combine 2D and 3D methods of imaging; the measurement itself can distinguish between patients with Class I and Class II skeletal patterns and can serve as a potential substitute for ANB and APDI. The new three-dimensionally based landmarks and measurements are reliable, and there is great potential for future use of 3D analyses for diagnosis and research.
authors.affiliation: a  Assistant Clinical Professor, Department of Orthodontics, Tufts University School of Dental Medicine, Boston, Mass.
authors.forename: Moonyoung
authors.initials: M
authors.lastname: Lee
authors.forename: Georgios
authors.initials: G
authors.lastname: Kanavakis
authors.forename: R Matthew
authors.initials: RM
authors.lastname: Miner
mesh_terms: D000539:Alveolar Process / Q000000981:diagnostic imaging; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D002508:Cephalometry / Q000379:methods* / Q000706:statistics & numerical data; D054893:Cone-Beam Computed Tomography / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007180:Incisor / Q000000981:diagnostic imaging; D008311:Malocclusion, Angle Class I / Q000000981:diagnostic imaging; D008312:Malocclusion, Angle Class II / Q000000981:diagnostic imaging; D008334:Mandible / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging; D008963:Molar / Q000000981:diagnostic imaging; D009295:Nasal Bone / Q000000981:diagnostic imaging; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies
keywords: CBCT; Cephalometric analysis; Cephalometric landmarks