Dentoalveolar changes related to mandibular forward growth in untreated Class II persons.
The purpose of this study was to investigate dentoalveolar changes related to mandibular forward growth in persons with Class II malocclusions. The longitudinal cephalometric films of 40 subjects with untreated Class II malocclusions from mean age 8.8 to 17.8 years (before and after pubertal growth) were analyzed and compared with the Bolton norms. There was no statistically significant difference in mandibular growth between the Class II samples and the Bolton norms upon cross-sectional comparison. In the Class II subjects, forward growth of the mandible was greater than that of the maxilla by 4.36 mm on average; the dentoalveolar complex moved forward relative to the maxillary basal bone (point A) 2.16 mm and moved backward relative to the mandibular basal bone (pogonion) 2.28 mm; a strong linear relationship (almost a 1:1 ratio) existed between mandibular forward growth and dentoalveolar complex movement (r = 0.881; y = 0.976 x + 0.183). Results indicated that the effect of forward growth of the mandible, which could potentially bring the lower dentition forward, vanished into the adaptation movements of the dentoalveolar complex through intercuspal locking. Disarticulating the occlusion to minimize the effects of the adaptive mechanism and taking advantage of normal mandibular forward growth could be fundamental biological bases in treating Class II malocclusions in growing patients.
You
Z H
ZH
Eastman Department of Dentistry, Orthodontics and Dentofacial Orthopedics, University of Rochester, Rochester, NY, USA. zhihao_you@msn.com
Fishman
L S
LS
Rosenblum
R E
RE
Subtelny
J D
JD
D000222:Adaptation, Physiological; D000293:Adolescent; D016022:Case-Control Studies; D002508:Cephalometry; D002648:Child; D005260:Female; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008312:Malocclusion, Angle Class II / Q000150:complications / Q000503:physiopathology*; D008334:Mandible / Q000254:growth & development*; D008644:Mesial Movement of Teeth / Q000150:complications / Q000503:physiopathology; D009811:Odontometry; D018709:Statistics, Nonparametric