The Study On The Changes Of The Hard Tissue Profile In Malocclusion Of Adolescence Angle Class â…¡ Division 1 After Treatment With Different Bicyspid Extraction

[Objective] The purpose of this study was to evaluate the changes of the hard tissue profile in classⅡdivision 1 malocclusion after different bicuspid Extraction treatment by cephalometrics and to demonstrate the difference of malocclusion development after extraction.[Methods] 80 adolescents with classⅡdivision 1 malocclusion were selected.20 adolescents were treated with four first bicuspid extraction(group1). 20 adolescents were treated with four second bicuspid extraction(group2). 20 adolescents were treated with first bicuspid extraction in maxillary and second bicuspid extraction in mandibular(group3). 20 adolescents were treated with non-extraction(group4). X-ray cephalometric analysis was performed with pre-treatment and post-treatment effects.[Results] After treatment U1-SN, L1-MP,U1-NA(°),Ul-NA(mm),L1-NB(°),L1-NB(mm) reduced significantly in extraction group. But no significant difference was found in each two groups in NE group U1-SN,L1-MP,U1-NA(°),Ul-NA(mm),L1-NB(°),L1-NB(mm)increased (p>0.05). significant difference was found in each two groups in Msa-OLP and Mia-OLP.[Conclusions] Extraction premolar treatment couldn't change the skeletal growth of adolescents in classⅡdivision 1 malocclusion. The changes of The incisor retraction was not found in extraction different bicuspid. First bicuspid Extraction was better in control of anchorage than second bicuspid extraction.