title: Orthodontic effects on dentofacial morphology in women with bilateral TMJ disk displacement.
abstract: OBJECTIVE
  To determine the difference in skeletal response to orthodontic treatment between patients with bilateral disk derangement and normal disk position of the temporomandibular joint (TMJ).
  
  
  METHODS
  Subjects consisted of 46 women whose malocclusions were treated only by orthodontics. All patients had TMJ magnetic resonance imaging (TMJ MRI) taken prior to orthodontic treatment. They were classified into three groups according to results of the TMJ MRI: bilateral normal disk position (BN), bilateral disk displacement with reduction (BDDR), and bilateral disk displacement without reduction (BDDNR). Twenty cephalometric variables were evaluated by the Kruskal-Wallis test to identify any differences in morphological changes between the three groups during orthodontic treatment.
  
  
  RESULTS
  This study showed that patients with BDDNR had more severe sagittal and vertical skeletal discrepancies than those with BN and BDDR at the pretreatment stage with discrepancies maintained after treatment. Compared to patients with BN, BDDR patients exhibited significant changes in SNB, N perpendicular to pogonion, SN to mandibular plane angle, total anterior facial height, ramus inclination, and effective mandibular length during treatment. This means that patients with BDDR showed more backward movement and rotation of the mandible than those with BN. In contrast, patients with BDDNR who had the most severe skeletal discrepancies did not show any significant skeletal changes during orthodontic treatment compared to those with BN or BDDR.
  
  
  CONCLUSIONS
  In patients with bilateral TMJ disk displacement, orthodontic treatment should be undertaken carefully to prevent backward rotation and movement of the mandible.
authors.affiliation: Department of Orthodontics, School of Dentistry and Dental Health Institute, Seoul National University, Korea.
authors.forename: Sug-Joon
authors.initials: SJ
authors.lastname: Ahn
authors.forename: Shin-Jae
authors.initials: SJ
authors.lastname: Lee
authors.forename: Tae-Woo
authors.initials: TW
authors.lastname: Kim
mesh_terms: D000328:Adult; D002508:Cephalometry; D005147:Facial Bones / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008310:Malocclusion / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy*; D008334:Mandible / Q000033:anatomy & histology; D009971:Orthodontics, Corrective; D011859:Radiography; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D019224:Temporomandibular Joint Disc / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013705:Temporomandibular Joint Disorders / Q000150:complications* / Q000000981:diagnostic imaging