目的 研究不同垂直骨面型安氏Ⅱ类1分类(Class II division 1，CⅡ1)牙弓变化，分析变化部位和程度，以及该变化与矢状向、垂直向异常的相关性，探讨CⅡ1牙弓横向变化的特点。方法 选患者80名，男39例，女41例，平均年龄22.6±5.5岁。实验、组：CⅡ1共60名,依据下颌平面角（FMA）分为高角组、均角组和低角组；对照组：安氏I类骨性I类(Class Ⅰ，CⅠ)均角。每组20例。使用Minics18.0对上下颌尖牙至第二磨牙的牙弓相关指标进行测量，统计及分析。结果 1.与对照组相比，高角组上下颌牙弓宽度狭窄(上颌第二磨牙：U7FA=61.45±3.47mm ,P=0.0076；上颌第一磨牙：U6FA=56.65±4.61mm，P=0.0371；上颌第二前磨牙：U5FA=50.28±3.18mm，P=0.0044；上颌第一前磨牙：U4FA=43.4±4.44mm，P=0.0059；下颌第二磨牙：L7FA=58.7±3.4mm，P=0.0029；下颌第一磨牙：L6FA=53.32±2.47mm，P=0.0001；下颌第二前磨牙：L5FA=45.21±2.83mm，P=0.0077；下颌第一前磨牙：L4FA=37.71±2.19mm，P=0.0008),均角组上颌牙弓宽度狭窄（上颌第一磨牙：U6FA=56.31±2.39mm，P=0.0005；上颌第二前磨牙：U5FA=51.66±2.17mm，P=0.043）；随着面高的增加，牙弓宽度越狭窄（上颌第二磨牙：U7FA，P=0.031;上颌第一磨牙：U6FA，P=0.016;上颌第二前磨牙：U5FA，P=0.003;上颌第一前磨牙：U4FA，P=0.001;下颌第二磨牙：L7FA，P=0.002;下颌第一磨牙：L6FA，P=0.000;下颌第二前磨牙：L5FA：P=0.006;下颌第一磨牙：L4FA，P=0.002）。2.牙弓宽度与ANB角、FMA角呈负相关，其中与FMA角负相关更明显(上颌第二磨牙：U7FA r=-.460，P=0.0492；上颌第一磨牙：U6FA r=-.447，P=0.0483；上颌第二前磨牙：U5FA r=-.473，P=0.0354；上颌第一前磨牙：U4FA r=-.493，P=0.0271;下颌第二磨牙：L7FA r=-.504，P=0.0234;下颌第一磨牙：L6FA r=-.447，P=0.0478;下颌第二前磨牙：L5FA r=-0.682，P=0.0009;下颌第一前磨牙：L4FA r=-.448，P=0.0286)。结论 1.与CⅠ相比，CⅡ1低角上下颌、均角下颌无牙弓宽度的改变，CⅡ1均角上颌、CⅡ1高角上下颌均出现明显狭窄，随着面高的增加，狭窄的程度越大。2.CⅡ1牙弓宽度可能与垂直骨面型呈负相关，与矢状骨面型呈弱的相关性，垂直向异常对横向宽度的影响要大于矢状向，垂直向是优先考虑的因素。3.CⅡ1牙弓宽度变化可能与功能状态。

Objective The purpose of this study was to investigate the changes of the dental arch width, the location and degree of the changes, and the correlation among the changes, the sagittal anomalies and the vertical anomalies in different vertical skeletal types of Class II division 1（CⅡ1). Methods The sample consisted of 80 adults. There were 39 males and 41 females with an average age of 22.6±5.5years. In the experimental group, there were 60 patients of CⅡ1. According to the FMA angle,60 patients were divided into high angle group, mean angle group and low angle group. The control group was the normal group of Class I（CⅠ）mean angle patients. Each group was 20 cases. Through Minics18.0, the relative indexes of dental arch  width of maxillary and mandibular canines to second molars were measured. The data has been statistically analyzed. Results  1.Dental arch width was more stenotic in maxillary and mandible of high angle group(U7FA:61.45±3.47mm,P=0.0076;U6FA:56.65±4.61mm,P=0.0371;U5FA:50.28±3.18mm,P=0.0044;U4FA:43.4±4.44mm,P=0.0059;L7FA:58.7±3.4mm,P=0.0029;L6FA:53.32±2.47mm,P=0.0001:L5 FA:45.21±2.83mm,P=0.0077;L4FA:37.71±2.19mm,P=0.0008) and maxillary of the average angle group（U6FA:56.31±2.39mm,P=0.0005;U5FA:51.66±2.17mm,P=0.043）than the normal group. With the increase of the facial height, the dental arch width was more stenotic.（U7FA:P=0.031;U6FA:P=0.016;U5FA:P=0.003;U4FA:P=0.001;L7FA:P=0.002;L6FA:P=0.000;L5FA:P=0.006;L4FA:P=0.002).2.Dental arch width was negatively correlated with ANB angle and FMA angle.The negative correlation with FMA angle is more obvious(U7FA: r=-.460,P=0.0492;U6FA:r=-.447,P=0.0483;U5FA:r=-.473, P=0.0354; U4FA:r=-.493,P=0.0271;L7FA:r=-.504,P=0.0234;L6FA:r=-.517,P= 0.0478;L5FA:r=-0.6 82,P=0.0009;L4FA:r=-.448,P=0.0286).Conclusion 1.Compared with CⅠ, CⅡ1 mandibular and maxillary with low angle,CⅡ1 mandibular with average angle have no changes in arch width,but the dental arch in the maxilla and mandible of CⅡ1 with high angle and the maxilla of CⅡ1 with average angle are stenotic. With the increase of the facial height the degree of stenosis is greater.2.CⅡ1may have a negative correlation with vertical skeletal types, and a weak correlation with the sagittal skeletal pattern. The vertical discrepancies have a greater influence on the transverse width than the sagittal discrepancies. The vertical direction is a priority factor. 3.Changes in CⅡ1 arch width may be related to functional status.