Class Ⅱ, Division 2 Malocclusion Pre-And Post-Treatment Of Cephalometric Study Of Early Permanent Dentition

Objective:The aim of this study was to compare the mandibular position, mandibular rotation ,facial height and shape of chin during orthodontic treatment of adolescent patients of Class II division 2 malocclussion with individual normal occlussion by cephalometric measurements,and to observe the difference of mandibular position, mandibular rotation ,facial height and shape of chin betweed using upper removable plate + Class II elastics and using reverse curve of Spee arch wires+Class II elastics,and to analyze the mechanism of changes in miandibular development and facial height ratio by using these two treatment methods.Methods:60 subjects (30 boys and 30 girls) with individual normal occlussion who were obtained in the groups aged 11 to 15 years were selected as control group. 26 Class II division 2 patients (13 boys and 13 girls, mean age 12.13 years) were selected as treatment group.Pre-treatment and post-treatment lateral cephalographs of 26 children and lateral cephalographs of control group were scanned.Data were obtained from lateral cephalograms by computer measurement andanalysis software.All patients had nonextraction treatment with Straight Wire Appliance and were divided into group A using upper removable plate + Class II elastics to correcte deep bite and group B using reverse curve of Spee arch wires+ Class II elastics to correcte deep bite.Results:Results show that anterior face height, the ratio of anterior facial height, chin height increased significantly after treatment in group A and B, but the change were more obviously in group A. There were some difference betweet group A and B after treatment, mandibular clockwise rotation and chin protrusion reduced after treatment in group A.Conclusion:This study shows that upper removable plate+Class II elastics and reverse curve of Spee arch wires+Class II elastics have the ability to correcte sagittal discrepancies of Class II division 2 patients in the early permanent dentition. Two methods corrected deep bite by extrusion of posterior teeth and tilt libially incisor, but upper removable plate + Class II elastics laid particular emphasis on posterior teeth extrusion. Reverse curve of Spee arch wires+ Class II elastics laid particular emphasis on tilt libially incisor. Comparing reverse curve of Spee arch wires+ Class II elastics, upper removable plate+Class II elastics could improve face aesthetics more effective , but emphasized much more on the cooperation of patients.