关键词: 口外弓, 安氏Ⅱ1类错畸形, 非拔牙矫治, face bow, Angle classⅡ1 malocclusion, non-extraction correction

Abstract: Objective To analyze clinical effect of extraoral appliance in nonextraction treatment of cases of Angle classⅡ1 malocclusion in different maxillary second molar eruption statuses.Methods 36 cases of Angle classⅡ1 malocclusion,who were treated with extraoral appliance in permanent dentition without extraction were chosen,aged 1015 years old with an average age of 12.5 years old.They were divided into four groups according to different maxillary second molar eruption statuses.Pretreatment and posttreatment lateral cephalometrics were analyzed by ANOVA to compare treatment effects.Results Maxilla had a very significant change before and after treatment.The group in which maxillary second molar germs were below maxillary first molar necks had the most indexes which were statistically significant (SNA,ANB,Wits distance,U6Ptv,overjet)， which were obviously better than those in the other three groups.Conclusions Traction with face bows can improve deep overjet in permanent dentition and correct molar relationship.It′s the best choice when the second permanent teeth haven′t erupted,especially when tooth germ is below first molar neck.