目的 使用锥形束计算机体层成像（cone beam computed tomography，CBCT）和Exam Vision研究替牙期活动扩弓对恒牙牙根发育及牙根吸收的影响。 方法 选取重庆医科大学附属口腔医院正畸科替牙期活动扩弓矫治病例17例作为试验组（平均年龄为10岁），功能矫治但未进行活动扩弓病例20例作为对照组（平均年龄为10岁）。所有患者矫治前后均拍摄CBCT。使用Exam Vision 分别测量试验组和对照组矫治前后上颌中切牙和上颌第一磨牙根尖孔宽度和牙根长度，利用SPSS 26.0进行统计学分析，研究2组矫治前后的差异。 结果 根尖孔宽度：右上颌中切牙牙根试验组（0.52±0.35）mm，对照组（0.98±0.78）mm；左上颌中切牙牙根试验组（0.47±0.39） mm，对照组（1.09±0.93） mm；右上颌第一磨牙腭根试验组（0.43±0.28）mm，对照组（0.61±0.34） mm；左上颌第一磨牙腭根试验组（0.59±0.24） mm，对照组（0.59±0.40） mm；试验组根尖孔闭合程度较对照组低。牙根长度：右上颌中切牙牙根试验组（0.48±0.77） mm，对照组（0.83±1.35） mm；左上颌中切牙牙根试验组（0.31±0.84） mm，对照组（0.78±1.16） mm；右上颌第一磨牙近中根试验组（0.37±0.72） mm，对照组（0.42±0.79） mm；右上颌第一磨牙远中根试验组（0.10±0.92） mm，对照组（0.70±1.09） mm；右上颌第一磨牙腭根试验组（0.43±0.96） mm，对照组（0.70±1.12） mm；左右上颌中切牙和右上颌第一磨牙牙根长度增长量对照组大于试验组。左上颌第一磨牙近中根试验组（0.59±0.79） mm，对照组（0.28±0.68） mm；左上颌第一磨牙远中根试验组（0.43±0.70） mm，对照组（0.40±1.06） mm；左上颌第一磨牙腭根试验组（0.62±0.84），对照组（0.61±0.97） mm；左上颌第一磨牙的牙根长度增长量试验组大于对照组。以根尖孔闭合情况分组的牙根长度：右上颌第一磨牙腭根闭合组（0.40±0.97） mm，未闭合组（-0.06±0.72） mm，牙根长度增长量闭合组大于未闭合组。左上颌第一磨牙腭根闭合组（0.20±0.59） mm，未闭合组（0.78±0.91） mm，牙根长度增长量未闭合组大于闭合组。 结论 替牙期使用活动扩弓改善上颌横向发育不足不会对恒牙牙根发育和牙根吸收造成明显影响。提示正畸医生对于上颌横向发育不足的儿童可以酌情采用活动扩弓进行改善。

Objective Removable expanders have been a typical treatment option for children with transverse maxillary deficiency in the mixed dentition period，but they may affect dental root development and cause root resorption. We aimed to use cone-beam computed tomography（CBCT） and Exam Vision to preliminarily assess the effects on the root development and root resorption of permanent teeth caused by maxillary expansion with removable appliances in the mixed dentition period. Methods We enrolled 17 patients treated with removable maxillary expansion during mixed dentition（experimental group；mean age，10 years） and 20 patients treated with functional correction without maxillary expansion（control group；mean age：10 years） in the Department of Orthodontics of Stomatological Hospital of Chongqing Medical University. CBCT was taken for all the subjects before and after treatment. We used Exam Vision to measure the length of the root and the width of the apical foramen of the maxillary central incisors and maxillary first molars before and after treatment. SPSS 26.0 was used for statistical comparisons. Results The width of the apical foramen：The root of right maxillary central incisor was （0.52±0.35） mm in experimental group and （0.98±0.78） mm in control group；The root of left maxillary central incisor was （0.47±0.39） mm in experimental group and （1.09±0.93） mm in control group；The palate root of the right maxillary first molar was （0.43±0.28） mm in experimental group and （0.61±0.34） mm in control group；The palate root of the left maxillary first molar was （0.59±0.24） mm in experimental group and （0.59±0.40） mm in control group；The degree of apical foramen closure was lower in experimental group than in control group. The length of the root： The root of right maxillary central incisor was （0.48±0.77） mm in experimental group and （0.83±1.35） mm in control group；The root of left maxillary central incisor was （0.31±0.84） mm in experimental group and （0.78±1.16） mm in control group；The mesial root of the right maxillary first molar was （0.37±0.72） mm in experimental group and （0.42±0.79）mm in control group；The distal root of right maxillary first molar was （0.10±0.92） mm in experimental group and （0.70±1.09） mm in control group；The palate root of the right maxillary first molar was （0.43±0.96） mm in experimental group and （0.70±1.12） mm in control group；The control group showed greater increases in the length of the root of the maxillary central incisors on both sides and the maxillary first molar on the right side. The mesial root of the left maxillary first molar was （0.59±0.79） mm in experimental group and （0.28±0.68） mm in control group. The distal root of the left maxillary first molar was （0.43±0.70） mm in experimental group and （0.40±1.06） mm in control group；The palate root of left maxillary first molar was （0.62±0.84） mm in experimental group and （0.61±0.97） mm in control group；The experimental group had an insignificantly greater increase in the length of the root of the maxillary first molar on the left side. The length of root divided by the closure status of apical foramina：The palate root of the right maxillary first molar was （0.40±0.97） mm in the closed group and （-0.06±0.72） mm in the unclosed group. The increasing amount of root length in the closed group was greater than in the unclosed group. The palate root of the left maxillary first molar was （0.20±0.59） mm in the closed group and （0.78±0.91） mm in the unclosed group. The increasing amount of root length in the unclosed group was greater than in the closed group. Conclusion For treating transverse maxillary deficiency during mixed dentition，removable expansion has no significant effects on the root development and root resorption of permanent teeth，suggesting that orthodontists can use removable appliances for treating children with transverse maxillary deficiency as appropriate. The optimal age for maxillary expansion should be further studied.