title: [Magnetic resonance imaging in the assessment of the temporomandibular joint structure following mandibular advancement].
abstract: OBJECTIVE
  To investigate the changes in the disc-condyle-fossa relationship following mandibular advancement.
  
  
  METHODS
  Twenty-five patients (10 boys and 15 girls, 11.1 +/- 1.1 years) with class II division 1 malocclusions were treated with Activator. The average treatment time was 10.9 months. Parasagittal MRIs in closed mouth position were analyzed before and after Activator treatment by means of the pair-t test.
  
  
  RESULTS
  Ca-Tm value [(-0.1 +/- 1.5) mm and (-0.6 +/- 0.9) mm] of the left temporomandibular joint (TMJ) and Ca-Ca' value [(2.3 +/- 0.8) mm and (1.8 +/- 0.5) mm] of the right TMJ were changed significantly after Activator treatment (P < 0.05). This indicated that the condyle was located anteriorly in the fossa. No significant changes were found in the disc-fossa relationship and disc-condyle relationship (P > 0.05).
  
  
  CONCLUSIONS
  Activator could promote the growth of the mandible and at the same time, it had no apparent negative influence on TMJ function.
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Jie-Jun
authors.initials: JJ
authors.lastname: Shi
authors.forename: Xiang-Long
authors.initials: XL
authors.lastname: Zeng
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000473:pathology* / Q000628:therapy; D019186:Mandibular Advancement; D011184:Postoperative Period; D013704:Temporomandibular Joint / Q000473:pathology*