title: Craniofacial growth in untreated skeletal Class II subjects: a longitudinal study.
abstract: Eighty-five (45 male and 40 female) skeletal Class II untreated subjects with low (< 27 degrees ), average (27 degrees - 36 degrees ), and high (> 36 degrees ) mandibular plane angles (MP-SN) were selected from the Bolton-Brush and the Burlington Growth Studies. Cephalograms of each subject at ages 9 and 18 were traced, and 28 parameters were measured. The difference in each parameter from ages 9 to 18 was calculated, and comparisons were made between the groups with low, average, and high angles. Results showed that for children at age 9, the high-angle group showed greater convexity, larger Y-axis and gonial angles, and greater anterior facial height, and the low-angle group had larger SNA and SNB angles, and greater posterior cranial base, mandibular body, ramus height, and posterior facial height. From ages 9 to 18, all the low-, average-, and high-angle groups showed a decrease of convexity (more flattened face) and a mandibular forward rotation (decreased MP-SN). The low-angle group displayed significantly more facial flattening and more mandibular forward rotation than did the high-angle group. Moreover, the mandibular incisors became more retroclined in the low-angle group and more proclined in the high-angle group with age. Comparisons between males and females showed similar skeletal growth patterns in angular measurements. However, a significant sex difference was noted in some linear measurements.
authors.affiliation: Department of Orthodontics, School of Dental Medicine, University of Pennsylvania, 4001 Spruce Street, Philadelphia, PA 19104-6003, USA. chunc@pobox.upenn.edu
authors.forename: Chun-Hsi
authors.initials: CH
authors.lastname: Chung
authors.forename: Wallace W
authors.initials: WW
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002508:Cephalometry; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008312:Malocclusion, Angle Class II / Q000503:physiopathology*; D008445:Maxillofacial Development; D012016:Reference Values; D012727:Sex Characteristics