title: [Effect of early treatment with the Twin-block appliance].
abstract: OBJECTIVE
  To evaluate the effectiveness of early treatment with the Twin-block appliance for the developing Class II division 1 malocclusion.
  
  
  METHODS
  A Total of 30 children with Class II division 1 malocclusion, 18 (8 male, 10 female) out of which received treatment with the Twin-block appliance, the other 12 cases (6 male, 6 female) without treatment served as control group. Cephalometric data were collected at the start and the end of the study and statistical analysis were applied.
  
  
  RESULTS
  Except the factor of growth, treatment with the Twin-block appliance resulted in reduction of ANB (1.55 degrees), overjet (5.46 mm) and correction of molar relationship (4.07 mm). These changes were due to the change of Pg/OLp, Co/OLp and mandibular length. The change of A/OLp was not significant. The skeletal effect contributing to the change on overjet and molar relation were 58% and 78% respectively.
  
  
  CONCLUSIONS
  Early treatment with the Twin-block appliance was effective in reducing ANB angle, overjet and correction of molar relationship. The changes were mainly profit from the favorable skeletal change of mandible, especially from its length, while the effect on maxillary was not significant.
authors.affiliation: Dept. of Orthodontics, School of Stomatology, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: Ma
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Liu
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Lu
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Zuo
authors.forename: Fu-Sheng
authors.initials: FS
authors.lastname: Dong
mesh_terms: D002508:Cephalometry; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II; D008334:Mandible; D008437:Maxilla; D008963:Molar; D017289:Orthodontic Appliances, Functional; D016896:Treatment Outcome