The Comparison Of Changes Of Dental Arch Width With Patients Of Class â…¡ Division 1 Malocclusion Treated By Two Different Extraction Modalities

Objective:To study the difference of changes of arch width between patients of class â…¡ division 1 malocclusions treated by two extraction mode to provide reference for clinic treatment.Methods:60 patients of class â…¡ division 1 were selected from the treated patients which were divided into two groups,30 patients treated by fixed appliance and extraction of four first premolar as group one ,the left were treated by fixed appliance and extraction of two upper first premolar and two lower second premolars as group two . Dental casts were taken at three time points during study: before treatment , after treatment and one year after treatment. Width between canines, premolars, and molars were measured by digital vernier caliper for all dental casts and changes of arch width of the three stages,during treatment,during follow-up and before treatment to the end of follow-up were compared between the two groups.Original data were analysised by spss 11.0.Result: 1.In group one,the intercanine width of of upper and lower arch increased after treatment,and then decreased slightly after follow-up,so the increasement kept mostly. The width between second premolar and molar of both arch decrease after treatment,and then increase slightly ,so the decreasement remained mostly.2.In group two, similar change showed in upper arch width and the width between the lower molars,but the intercanine and...