title: [The effect of cervical headgear and lower utility arch on the control of vertical dimension in tooth and jaw].
abstract: OBJECTIVE
  To evaluate the effect of cervical headgear and lower utility arch in growing skeletal Class II division 1 patients.
  
  
  METHODS
  The patients were divided into 3 groups, the first group was treated with cervical headgear alone (n=20), the second group was treated with cervical headgear and lower utility arch (n=20), and the third group was a control group without treatment (n=20). Cephalometric radiographs were taken and analyzed with SPSS15.0 software package. Student's t test was used to determine if there was significant difference among the 3 groups.
  
  
  RESULTS
  Anterior facial height and ramus height displayed significantly increase in the treatment groups than those in the control group; the lower utility arch produced intrusion and lingual tipping of the mandibular incisors and distal tipping without extrusion of the mandibular molars; compared with the control group, maxillary molar total extrusion produced by cervical headgear treatment was not more than 1mm at average.
  
  
  CONCLUSIONS
  The treatment groups show significant reduction in maxillary protrusion; significant increase in the anterior descent of the PP and ramus height, as a result, mandibular plane orientation is relatively unchanged. The treatment groups have maxillary molar extrusion less than 1mm, which can be considered clinically not significant. The lower utility arch produces mandibular incisor intrusion and lingual tipping, the mandibular molars tip distally without extrusion, the lower utility arch does not influence the mandibular rotation.
authors.affiliation: Department of Orthodontics, Hangzhou Dental Hospital. Hangzhou 310006,Zhejiang Province, China. repaint007@163.com
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Luo
authors.forename: Ren-fei
authors.initials: RF
authors.lastname: Wang
mesh_terms: D002508:Cephalometry; D005115:Extraoral Traction Appliances; D006801:Humans; D007180:Incisor; D008334:Mandible; D008437:Maxilla; D008963:Molar; D014070:Tooth; D014087:Tooth Movement Techniques; D014716:Vertical Dimension