Dawn M Wagner1, Chun-Hsi Chung. 1. Department of Orthodontics, University of Pennsylvania School of Dental Medicine, Robert Schattner Center, 240 S. 40th Street, Philadelphia, PA 19104, USA.
Abstract
INTRODUCTION: The purpose of this study was to investigate maxillary and mandibular transverse growth in untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18. METHODS: Eighty-one untreated white girls with low (< or = 27 degrees , n = 16), average (> 27 degrees to < 37 degrees , n = 41), and high (> or = 37 degrees , n = 24) mandibular plane angles at age 6 were selected from the Bolton-Brush and Burlington Growth Studies. For each subject, longitudinal posteroanterior cephalograms at different ages (from ages 6 to 18) were traced, and the widths of maxilla and mandible were measured. All the measurements were converted by using a magnification factor of 8.5% (the subject-to-film distance was set at 13 cm). RESULTS: At age 6, the high-angle group had narrower maxillary and mandibular widths than the low-angle group, and this trend continued until age 18. From ages 6 to 14, maxillary width showed a steady and similar rate of increase for all 3 groups (0.90-0.95 mm per year), yet a plateau was reached at age 14 for all groups. Mandibular width increased at a steady rate (about 1.6 mm/year) for all 3 groups until age 14, and a plateau was reached for the high-angle group. For the low- and average-angle groups, mandibular growth continued from ages 14 to 18 but at a slower rate (0.85 mm and 0.39 mm per year, respectively). CONCLUSIONS: Vertical facial patterns (with low or high mandibular plane angles) might play a strong role in the transverse growth of the maxilla and the mandible.
INTRODUCTION: The purpose of this study was to investigate maxillary and mandibular transverse growth in untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18. METHODS: Eighty-one untreated white girls with low (< or = 27 degrees , n = 16), average (> 27 degrees to < 37 degrees , n = 41), and high (> or = 37 degrees , n = 24) mandibular plane angles at age 6 were selected from the Bolton-Brush and Burlington Growth Studies. For each subject, longitudinal posteroanterior cephalograms at different ages (from ages 6 to 18) were traced, and the widths of maxilla and mandible were measured. All the measurements were converted by using a magnification factor of 8.5% (the subject-to-film distance was set at 13 cm). RESULTS: At age 6, the high-angle group had narrower maxillary and mandibular widths than the low-angle group, and this trend continued until age 18. From ages 6 to 14, maxillary width showed a steady and similar rate of increase for all 3 groups (0.90-0.95 mm per year), yet a plateau was reached at age 14 for all groups. Mandibular width increased at a steady rate (about 1.6 mm/year) for all 3 groups until age 14, and a plateau was reached for the high-angle group. For the low- and average-angle groups, mandibular growth continued from ages 14 to 18 but at a slower rate (0.85 mm and 0.39 mm per year, respectively). CONCLUSIONS: Vertical facial patterns (with low or high mandibular plane angles) might play a strong role in the transverse growth of the maxilla and the mandible.
Authors: Craig McMullen; Najla N Al Turkestani; Antonio C O Ruellas; Camila Massaro; Marcus V N N Rego; Marilia S Yatabe; Hera Kim-Berman; James A McNamara; Fernanda Angelieri; Lorenzo Franchi; Peter Ngan; Hong He; Lucia H S Cevidanes Journal: Am J Orthod Dentofacial Orthop Date: 2021-12-31 Impact factor: 2.711