title: [Efficacy evaluation of fixed Twin-block appliance and tooth extraction in skeletal Class II malocclusion].
abstract: OBJECTIVE
  To evaluate the skeletal and dentoalveolar effects of Twin-Block combined with straight wire appliances and tooth extraction in the treatment of skeletal Class II malocclusion with mandibular retrognathia in growing individuals.
  
  
  METHODS
  The sample comprised 31 growing individuals with skeletal Class II and mandibular retrognathia, divided into 2 groups. One group (18 patients) was treated with fixed Twin-block combined with fixed appliance; the other group (13 patients) was only treated with fixed appliance after tooth extraction. Lateral cephalograms pretreatment and posttreatment were taken before and after Twin-block treatment and after all fixed appliance treatment. Pancherz's cephalometric measurements were analyzed statistically. Intragroup and intergroup changes of the two groups were evaluated by test using SPSS 15.0 software package.
  
  
  RESULTS
  According to Pancherz's analysis, mandibular length increased, point Pg, mandibular incisors and first molars moved forward, maxillary incisors moved backward, overjet decreased (P<0.05) after treatment with Twin-block and fixed appliance. Within the rectification of anterior overjet, proportion of dentofacial factor was 39.5%, skeletal factor was 60.5%. Within the rectification of posterior relationship, proportion of dentofacial factor was 44.9%, skeletal factor was 55.1%.
  
  
  CONCLUSIONS
  Twin-block combined with fixed appliance treatment can efficiently promote mandibular growth, restrict forward growth of maxilla to some extent, correct incisor and molar relationship and improve skeletal profile in growing skeletal Class II individuals with mandibular retrognathia.
authors.affiliation: Department of Orthodontics, Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology. Shanghai 200011, China.E-mail:gongyao0328@hotmail.com.
authors.forename: Yao
authors.initials: Y
authors.lastname: Gong
authors.forename: Quan
authors.initials: Q
authors.lastname: Yu
authors.forename: Pei-lun
authors.initials: PL
authors.lastname: Li
authors.forename: Hong-hong
authors.initials: HH
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Wei
authors.forename: Gang
authors.initials: G
authors.lastname: Shen
mesh_terms: D002508:Cephalometry; D003729:Dental Care; D006801:Humans; D007180:Incisor; D008310:Malocclusion; D008312:Malocclusion, Angle Class II; D008334:Mandible; D008437:Maxilla; D008963:Molar; D017289:Orthodontic Appliances, Functional; D063173:Retrognathia; D014081:Tooth Extraction