title: Micro X-ray computed tomography analysis for the evaluation of asymmetrical condylar growth in the rat.
abstract: OBJECTIVE
  To investigate the influence of forced lateral bite on mandibular growth, micro X-ray computed tomography (CT) was used for the purpose evaluating condylar cartilage and cancellous bone formation in 10 male Wister rats (3 weeks of age). SETTINGS AND SAMPLE POPULATION: The rats were divided into two groups--experimental and control. In experimental group, an inclined crown was cemented onto the maxillary incisors to produce 2.5 mm shift toward the left side during mastication. Right-left differences in whole mandibular length, mandibular height, condylar size, trabecular structure of the condylar head and three-dimensional (3-D) finite element analysis were assessed using 3-D images reconstructed from micro X-ray CT scans when the mice had reached 21 weeks.
  
  
  RESULTS
  Asymmetrical growth was found in the experimental group, in which the left condylar head became thicker and shorter than the right condylar head during development. When comparing the left and right condyles of the experimental animals, histomorphometric analysis from micro X-ray CT showed that the bone volume (BV) of the cancellous bone, the surface area of the cancellous bone (BS), the BS/BV ratio, the BV fraction (BV/TV), and the trabecular thickness and trabecular number were less for the right condyle than for the left condyle.
  
  
  CONCLUSIONS
  These findings suggested that artificial changes in the mastication do influence the growth of condylar head, condylar bone trabecular structure, and mineralization.
authors: Department of Orthodontics, Showa University, Tokyo, Japan. nakanou@cb3.so-net.ne.jp
authors: H
authors: H
authors: Nakano
authors: J
authors: J
authors: Watahiki
authors: M
authors: M
authors: Kubota
authors: K
authors: K
authors: Maki
authors: Y
authors: Y
authors: Shibasaki
authors: D
authors: D
authors: Hatcher
authors: A J
authors: AJ
authors: Miller
mesh_terms: D000818:Animals; D015519:Bone Density / Q000502:physiology; D002113:Calcification, Physiologic / Q000502:physiology; D005146:Facial Asymmetry / Q000000981:diagnostic imaging / Q000209:etiology; D020342:Finite Element Analysis; D006132:Growth Plate / Q000254:growth & development; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008310:Malocclusion / Q000150:complications / Q000503:physiopathology; D008334:Mandible / Q000254:growth & development; D008335:Mandibular Condyle / Q000000981:diagnostic imaging / Q000254:growth & development*; D008852:Microradiography; D010012:Osteogenesis / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D014057:Tomography, X-Ray Computed / Q000379:methods*