儿童下牙弓发育的测量

MEASUREMENTS OF MANDIBULAR DENTAL ARCH GROWTH IN CHILDREN

本研究测量了１９３６名６－１２岁男女儿童的下颌牙弓的宽度和弦长．儿童前牙弓在７－９岁时增长最快，为此时恒尖牙萌出所致．１０岁以后各年龄组均数差异检验没有显著性意义．在整个替牙期，儿童前牙弓宽度约增加２ｍｍ，弦长增加１．８ｍｍ，儿童后牙弓的宽度和弦长约增加１ｍｍ左右．男孩前牙弓宽度比女孩大１ｍｍ左右．后牙弓的宽度和弦长在各年龄组均为男大于女，约１ｍｍ左右．可以把小学年龄阶段儿童的牙列分为乳牙弓、第１恒磨牙弓和第２恒磨牙弓３种，在小学儿童中的比例分别为２．１％、７６％、２１．９％．

This study measures the dental arches of 1936 children, aged de 12 years. The anterior dental arch increases fast from 7 to 9 years, because of the eruption of canine. It is stand still after 11 years old. During the mixed dentitinn period, the width of anterior dental arch increases about 2mm. and the hypotenuse about 1.8mm. The width and hypotenuse of posterior dental arch increase about 1mm. The size of anterior dental arch in boys is larger than that in girls, less than 1mm Both of width and hypotenuse of posterior dental amah in boys are larger about 1mm than in girls in all classes. From 6 to 12 years, there are the Paltry dental arch, the First molar dental arch and the second molar dental arch among children. Their proportions are 2.1%, 76% and 21.9% respeCtively.