title: [Study of the mandibular growth phases and quantities in Shanghai adolescents].
abstract: OBJECTIVE
  To study the growth phases and quantities of mandible in Shanghai adolescents.
  
  
  METHODS
  The samples included 480 Shanghai adolescents from 8-20 years of age, 240 were male and 240 were female. Both male and female groups were divided into 6 consecutive developmental periods according to cervical vertebral maturation stages. Their cephalometric radiographs were measured and analyzed. Independent-sample t test was conducted by SPSS 15.0 software package.
  
  
  RESULTS
  The total mandibular length (Co-Gn) increased significantly from CVMS1 to CVMS2 and CVMS3 to CVMS4 in both male and female group. For male the maximum increase was from CVMS3 to CVMS4 (P<0.01,average 9.54 mm), while female was from CVMS1 to CVMS2(P<0.01,average 9.09 mm). The height of mandibular ramus (Co-Go) increased continuously from CVMS2 to CVMS5 in male group, the significant increase was observed from CVMS2 to CVMS3 (P<0.01, average 8.80 mm). The significant increase in female group was observed from CVMS1 to CVMS2 (P<0.01, average 6.51 mm). In male group, the greatest increase of the mandibular base length (Go-Pog) appeared from CVMS3 to CVMS4 (P<0.01, average 7.55 mm), while in female group, it occurred from CVMS1 to CVMS2 (P<0.01, average 5.73 mm).
  
  
  CONCLUSIONS
  The growth amounts of total mandibular length (Co-Gn), mandibular base length (Go-Pog) and ramus length are different at every CVM stages in male and female groups. The present finding will help to make reasonable diagnosis and treatment planning.
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:sunyan173@126.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Rong-jing
authors.initials: RJ
authors.lastname: Chen
authors.forename: Pei-jun
authors.initials: PJ
authors.lastname: Lu
authors.forename: Gang
authors.initials: G
authors.lastname: Shen
mesh_terms: D000293:Adolescent; D002508:Cephalometry; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000254:growth & development*