title: [Soft tissue angle evaluation of fixed Twin-Block appliance treatment and tooth extraction treatment in skeletal Class II malocclusion].
abstract: OBJECTIVE
  This cephalometric study was designed to evaluate the soft tissue profile effects of Twin-Block combined with straight wire appliances in the treatment of skeletal Class II malocclusion with mandibular retrognathia in growing individuals by angulation.
  
  
  METHODS
  The sample comprised 31 growing individuals with skeletal Class II and mandibular retrognathia, which were 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. Pretreatment and posttreatment lateral cephalograms were taken before and after Twin-Block treatment and after all the fixed appliance treatment. Angular cephalometric measurements of soft tissue were analyzed statistically. Intragroup and intergroup changes of the 2 groups were evaluated by Student's t test using SPSS 15.0 software package.
  
  
  RESULTS
  Significant difference of FH-N'Pg', G-Pn-Pg', LiSi-SN and SnLs-SiLi were discovered in both groups (P<0.05). With Twin-Block combined with fixed appliance, N'-Sn-Pg', Sn-N'-Si and Si-N'-S changed significantly, while LsSn-SN and Z angle differed significantly before and after treatment with extraction and fixed appliance. After treatment of Twin-Block combined with fixed appliance, Sn-N'-Si decreased significantly, and the difference between the change of the 2 groups was significant. Meanwhile LsSn-SN was stable in combined treatment group while it decreased greatly after extraction.
  
  
  CONCLUSIONS
  Compared with extraction with fixed appliance treatment, Twin-Block combined with fixed appliance treatment is more favorable in promoting lower facial profile in growing skeletal Class II individuals with mandibular retrognathia.
authors.affiliation: Department of Orthodontics, Shanghai 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.affiliation: Department of Orthodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; Shanghai Key Laboratory of Stomatology. Shanghai 200011, China.
authors.forename: Pei-lun
authors.initials: PL
authors.lastname: Li
authors.affiliation: Department of Orthodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; Shanghai Key Laboratory of Stomatology. Shanghai 200011, China.
authors.forename: Hong-hong
authors.initials: HH
authors.lastname: Wang
authors.affiliation: Department of Orthodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; Shanghai Key Laboratory of Stomatology. Shanghai 200011, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Department of VIP Consultants, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; Shanghai Key Laboratory of Stomatology. Shanghai 200011, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wei
authors.affiliation: Department of Orthodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; Shanghai Key Laboratory of Stomatology. Shanghai 200011, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Shen
mesh_terms: D002508:Cephalometry; D003131:Combined Modality Therapy; D003729:Dental Care; D005147:Facial Bones; D006801:Humans; D008310:Malocclusion; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008334:Mandible; D017289:Orthodontic Appliances, Functional; D063173:Retrognathia / Q000628:therapy; D014081:Tooth Extraction