title: [Evaluation of craniofacial asymmetry based on cone-beam CT image].
abstract: Cone-beam CT (CBCT) was developed for the three-dimensional (3D) imaging of the maxillofacial area and has become popular in dentistry,  orthodontics, and maxillofacial surgery. The advantages of CBCT include less radiation exposure (than conventional CT), less artifacts, and submillimeter  spatial resolution. CBCT has been shown to produce accurate 3D images of the craniofacial region and a 1-to-1 image-to-reality ratio, which has  greatly reduced errors of frontal cephalometry and improved our ability to diagnose asymmetry. Several new analyses to diagnose asymmetries on 3D  images described in recent literature were reviewed, including 3D linear and angular measurements, mirror-image analysis (superimposition of the mirror  image of the anatomically correct part of the anatomy over the deformity), 3D cephalometric analysis based on constructing an individual coordinate  system for each facial unit or element (local coordinate systems) to differentiate them from the world coordinate system (whole head orientation), and  method of application of asymmetry indices.
authors: Department of Orthodontics, Peking University School, Beijing, China.
authors: Xiao-yun
authors: XY
authors: Zhang
authors: Tian-min
authors: TM
authors: Xu
mesh_terms: D002508:Cephalometry; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D019465:Craniofacial Abnormalities / Q000000981:diagnostic imaging*; D005146:Facial Asymmetry / Q000000981:diagnostic imaging*; D005147:Facial Bones / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional; D012886:Skull / Q000000981:diagnostic imaging*