title: Longitudinal study of relative growth rates of the maxilla and the mandible according to quantitative cervical vertebral maturation.
abstract: BACKGROUND
  The purpose of this study was to investigate the relative growth rates (RGR) of the maxilla and the mandible according to quantitative cervical vertebral maturation (QCVM) of adolescents with normal occlusion.
  
  
  METHODS
  Mixed longitudinal data were used. The sample included 87 adolescents (32 boys, 55 girls) from 8 to 18 years of age with normal occlusion, selected from 901 candidates. Sequential lateral cephalograms and hand-wrist films were taken once a year for 6 consecutive years. The growth magnitude (GM) and RGR of the maxilla and the mandible were measured and analyzed.
  
  
  RESULTS
  GM and RGR were not always consistent, because subjects had different periods of time between the QCVM stages. GM was not as reliable as RGR. RGR had no significant sex differences in the maxilla and the mandible, in spite of different decelerating curves. However, statistically significant sex differences were found in the GM of mandibular measurements. The greatest growth potentials were not synchronized between the maxilla and the mandible. For both sexes, the greatest RGR of maxillary length and height was in QCVM stage I; then, deceleration occurred. The greatest RGR of mandibular length and height was in QCVM stage II, and the next largest was in QCVM stage I.
  
  
  CONCLUSIONS
  Understanding the RGR can provide references for orthodontic treatment and orthognathic surgery.
authors.affiliation: Department of Stomatology, Union Hospital, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Chen
authors.forename: Jiarong
authors.initials: J
authors.lastname: Liu
authors.forename: Tianmin
authors.initials: T
authors.lastname: Xu
authors.forename: Jiuxiang
authors.initials: J
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002508:Cephalometry / Q000706:statistics & numerical data; D002574:Cervical Vertebrae / Q000254:growth & development*; D002648:Child; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008334:Mandible / Q000254:growth & development*; D008437:Maxilla / Q000254:growth & development*; D012016:Reference Values; D012737:Sex Factors