title: Quantitation of zygomatic complex symmetry using 3-dimensional computed tomography.
abstract: OBJECTIVE
  To improve the clinical evaluation of the symmetry of the zygomatic complex (ZMC), the authors developed a new method to measure the eminence and width of the ZMC using 3-dimensional (3D) computed tomography (CT). The accuracy and reproducibility of the ZMC symmetry evaluation using this method were investigated.
  
  
  METHODS
  Spiral CT was carried out in 50 volunteers with visually symmetric faces. Based on an exact craniofacial midsagittal plane, a 3D coordinate system was constructed and used to measure the eminence and width of the ZMC. Absolute differences between the bilateral eminences and widths were calculated as ΔE and ΔW, respectively. The ZMC eminence also was measured based on traditional methods using anatomic landmarks, and the bilateral absolute difference was calculated to serve as a control (ΔcE).
  
  
  RESULTS
  The ΔE value was lower than the ΔcE value (0.6 vs 1.75 mm; P < .001). None of the results for ΔE were larger than 2 mm, and 7 results (3.5%) for ΔW were larger than 2 mm. By comparison, 57 results (28.5%) for ΔcE were larger than 2 cm (P < .001). The intraclass correlation coefficient (ICC) indicated almost perfect agreement for inter- and intraexaminer reliabilities for ΔE (ICC, 0.82 to 0.86) and ΔW (ICC, 0.81 to 0.85) measurements, and moderate agreement for inter- and intraexaminer reliabilities was obtained for ΔcE (ICC, 0.61 to 0.68) measurements.
  
  
  CONCLUSIONS
  This new method is practical and valuable in the clinical evaluation of ZMC symmetry.
authors.affiliation: Resident, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Gong
authors.affiliation: Resident, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: He
authors.affiliation: Attending Physician, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: He
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Jin-gang
authors.initials: JG
authors.lastname: An
authors.affiliation: Resident, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Professor and Department Head, Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China. Electronic address: zhangyi2000@263.net.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D059925:Anatomic Landmarks / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D002508:Cephalometry / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data*; D008297:Male; D009295:Nasal Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D009915:Orbit / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012658:Sella Turcica / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D036542:Tomography, Spiral Computed / Q000706:statistics & numerical data*; D055815:Young Adult; D015050:Zygoma / Q000033:anatomy & histology* / Q000000981:diagnostic imaging