Extraction treatment of Class Ⅱ~1 cases: What can we change the patient's hard tissue profile?
WT5”BX]XU Tianmin, WANG Li, ZENG Jinling, et al Department of Orthodontics, School of Stomatology, Beijing Medical University, Beijing 100081 [WT5”HZ]
Objective [WT5”BZ]To evaluate hard tissue profile changes and stability in the Class Ⅱ 1 cases after extraction treatment with conventional fixed appliance.[WT5”HZ]Methods [WT5”BZ]Thirty Class Ⅱ 1 extraction cases were chosen as study sample. Computerized cephalometrics on X ray films before treatment, after treatment and after 4 year following up were performed repeatedly by three authors. The changes were compared by paired t test.[WT5”HZ]Results [WT5”BZ]After treatment: SNA reduced 1.0° (p 0.05 ),U 1 PP reduced 14.9° (p 0.001 ),U 1 FHV reduced 3.1mm (p 0.001 ), SNPg increased 0.04° (p 0.05 ). After following up: SNA increased 0.05° (p 0.05 ),U 1 PP increased 3.9° (p 0.05 ),U 1 FHV increased 0.9mm (p 0.05 ),SNPg increased 0.6° (p 0.05 ).[WT5”HZ]Conclusion [WT5”BZ]The main changes of extraction treatment in the Class Ⅱ 1 cases were the reduction of maxillary prominence, especially the prominence and the proclination of upper anterior teeth, which even after small relapse, still showed significantly statistical and clinical differences compared with pre treatment measures. [WT5”HZ]