A Comparative Study Of The Efficacy Of Single-and Bi-maxillary Extraction Treatment Of Adult Class â…¡ Division1Classification

Objective: The effects of two alternative treatment modalities for Class II division I inadult were compared so as to investigate the better treatment for Class II division Imalocllusion.Methods: thirty-six adults withAngle class Ⅱdivision1were treated and divided intotwo groups, group Awas treated with extraction of two maxillary first bicuspids, group Bwas treated with extraction of two maxillary first bicuspids and two mandibularposterior teeth. Pre-treatment and post-treatment lateral cephalograms were analyzedusing cephalometric analysis and the data was analyzed by spss13.0.Results: In group A, the length of UL-E,LL-E,U1-AP,UL-Pn,LL-Pn,and the angle of∠U1-FH,H decreased significantly, the angle of∠L1-MP,∠OP-SN,∠U1-LI,Z,increasedsignificantly. In group B the length of UL-E,LL-E,UL-Pn,LL-Pn,U1-AP,U1-NA,U1-NBand the angle of∠U1-FH,∠L1-MP,H decreased significantly, the angle of∠U1-L1,OP-SN，Z increased significantly. Those mean that upper and lower lip retrudedsignificantly in both groups. The length of U1-AP,LL-E,UL-Pn,LL-Pn in group B weredecreased larger significantly than in group A. And the Z angle increment in group B waslarger than group AConclusion:1, Both methods could achieve the goal of retruding upper incisors, improving the profiles;while both maxillary and mandibular extraction could achieve more significantly change.2, The effect of bimaxillary extraction is more significantly; yield more retrusion in theincisors, easier access to coordinated, beautiful profile. Single maxillary extraction ismore suitable for patients with shallow trench lip chin, and lower lip eversion slightly.Clinical applications should be selected based on the chief complaint and a goodindication of specific circumstances.3,As the soft tissue profile measurement reference plane, Pn plane (also called Dreyfusline) is more objective than the E-plane.