关键词: 骨性Ⅲ类错牙合, 拔牙, 多曲唇弓

Abstract:

Objective    To  study  the clinical application of lower  second  molars  extraction and treatment using  MEAW in non-surgical patients  with skeletal Class Ⅲ malocclusion.  Methods    Seven non-surgical patients of skeletal Class Ⅲ malocculsion（ male 3， female 4，  age ranging 13 ～16 years old，  mean age 14.3）were included in the study. They were treated by MEAW technique after extraction of lower second molars；cephalometric films at the beginning and end of treatment were analyzed using cephalometric analysis. Results    After treatment，all the patients reached normal occlusion relationship， the cross bite of anterior tooth was corrected，and reached the normal overbite and overjet. The lower first molars was moved  3.1 mm posteriorly ，the lower incisors were moved 2.8 mm lingually，and the angle of ANB were increased 1.2 degree.  The difference was of statistical significance.  Conclusions    The treatment of MEAW technique after extraction of lower second molars is suitable for the non-surgical patients of skeletal Class Ⅲ malocclusion in the period of permanent teeth， whose dental germs of  lower third molar are normal，and whose dentition is crowded in the mandible，and has a tendency of openbite.

Key words: skeletal , Class Ⅲ malocclusion ；tooth extraction ；MEAW