Orthodontics Department, Peking University, Beijing, China.
Am J Orthod Dentofacial Orthop. 2010 Feb;137(2):187-93. doi: 10.1016/j.ajodo.2008.03.021.
The purpose of this study was to investigate the changes of available mandibular space in the posterior dental arch of teenagers from 13 to 18 years old.
Longitudinal cephalograms of 28 adolescents (13 boys, 15 girls) with normal occlusion, selected from among 901 candidates, were taken annually from 13 to 18 years of age inclusively. Modified analyses with occlusal plane and occlusal plane perpendicular as reference planes were used to evaluate the changes of available space of the posterior mandibular arch.
From 13 to 18 years of age, significant differences of mandibular posterior space were found among ages and sexes. The total increases of available space were 5.12 mm in the girls and 5.79 mm in the boys. For girls before age 16 and boys before age 17, the increased available space was contributed mainly by resorption of bone on the anterior border of the ramus. Mesial drift of the dental arch did not occur until the eruption of the third molars. The average available spaces increased 1.22 mm in girls less than age 16 and 1.45 mm in boys less than age 17 per side per year.
The prediction of available space in the posterior mandibular arch should be based on age and sex.
本研究旨在探讨青少年从 13 岁到 18 岁时后牙弓可用下颌间隙的变化。
从 901 名候选者中选择了 28 名具有正常咬合的青少年（13 名男孩，15 名女孩），每年从 13 岁到 18 岁进行纵向头颅侧位片拍摄。使用牙合平面和牙合平面垂线作为参考平面的改良分析来评估下颌后牙弓可用空间的变化。
从 13 岁到 18 岁，年龄和性别之间存在明显的下颌后间隙差异。女孩的可用空间总增加量为 5.12mm，男孩为 5.79mm。在女孩 16 岁之前和男孩 17 岁之前，可用空间的增加主要是由于髁突前骨的吸收。第三磨牙萌出之前，牙弓不会发生近中漂移。女孩年龄小于 16 岁时，每年每侧平均可用空间增加 1.22mm，男孩年龄小于 17 岁时，每年每侧平均可用空间增加 1.45mm。
预测下颌后牙弓的可用空间应基于年龄和性别。
