均采用直丝弓矫治器矫治，应用螺旋推簧扩展间隙及上颌前方牵引。

They were all treated with straight wire appliance and helical spring to expand clearance.

youdao

均采用直丝弓矫治器矫治，应用螺旋推簧扩展间隙及上颌前方牵引。

They were all treated with straight wire appliance and helical spring to expand clearance.

youdao