上颌第二恒磨牙不同发育阶段受到颊侧向后推力的临床观察

The clinical observation of buccal backward thrust in different development stages of the second permanent molar

目的探讨采用口外弓推磨牙向后结合固定矫治器治疗安氏Ⅱ类1分类错畸形对第二恒磨牙萌出产生的影响.方法选取2016年1月至2017年12月安氏II类1分类患者33例,年龄8~14周岁,采用固定矫正器结合口外弓联合头帽治疗,正畸结束时,观察第二恒磨牙是否顺利萌出,并测量其在正中矢状面牙体长轴及第二恒磨牙间宽度的变化.结果患者33例,正畸结束时,25例正常萌出;8例患者上颌第二恒磨牙尚未在口腔内萌出,此时牙发育阶段为8~9,且未观察到明显萌出阻力.在不同发育阶段,上颌第一恒磨牙的牙体长轴基本维持不变;上颌第二恒磨牙的牙体长轴轻度向远中倾斜,各发育阶段倾斜程度差异无统计学意义(P>0.05).双侧第一恒磨牙间距离平均增加2.95mm,第二恒磨牙平均增加1.63mm,各组间差异无统计学意义(P>0.05).结论青少年轻度前突或轻中度拥挤的患者,颊侧推磨牙向后的力在有效控制下,对不同发育阶段的第二恒磨牙萌出不会产生不利影响.

Objective To explore the effect on the eruption of the second permanent molar at different development stages when a fixed orthodontic appliance combined with the extraoral arch were used to treat adolescent patients with Class II division 1 malocclusion.Methods From January 2016 to December 2017,33 patients were chosen in the oral clinic of Hangzhou Yaboyi,aged from 8 to 14 years old.They were treated with a fixed orthodontic appliance combined with a extraoral arch.At the end of orthodontic treatment,it was observed that whether the second permanent molar was erupted successfully.The change of tooth length axis in the median sagittal plane and arch-width in the horizontiil plane were measured.Results Among the 33 patients in this study,at the end of the orthodontic treatment,8 patients'maxillary second pennanent molars had not erupted in the oral cavity,and the teeth were observed to be at 8?9 developmental stages with no obvious eruption resistance.In the rest 25 cases,maxillary second permanent molars were erupted normally.At different developmental stages,the long axis of the maxillary first permanent molar was basically unchanged,the m?ixillary second pennanent molars were slightly distal inclined.There was no significant difference between the groups.The average distance between the first permanent molars on both sides increased by 2.95 mm,and 1.63 mm in the second permanent molars.The difference between the groups was not statistically significant.Conclusion In adolescents with mild protmsion or mild to moderate crowding,there is no adverse effect on the second molars at different stages of development if the buccal thnist is under effective control.