Clinical effects about the therapy of patients with Class II~1 maloocclusion by Twinblock appliance

Objective To evaluate the effects of skeletal and dental changes of Angle's Class Ⅱ~1 malocclusion patients with retrusive mandible treated by Twinblock appliance.Methods Twenty patients with Class Ⅱ~1 malocclusion(age from 10 to 13 years) were treated by Twinblock appliance in puberal growth spurt.Lateral Cephalometric films were taken at the beginning and the end of the treatment.Cephalometric analysis were used to evaluate the effects of treatment.Results ①After 6～12 months(average 8 months) treatment,Class Ⅱ~1 malocclusion relationships were corrected to Class Ⅰ in all patients.Overjet decreased from 6.8 mm to(2.0) mm and overbite decreased from 6.0 mm to 1.2 mm,and the profile of patients was improved.②The skeletal changes were increased significantly in Pg.And the present of skeletal changes were 47.9% in the total changes of overjet and 48.9% in the total changes of molar's relationship.The change of mandibular plane angle was not significant.But the mandible and maxilar biteplanes were clockwise rotation and the change of lower facial height was significant.Conclusion Twinblock appliance is effective to correct Class Ⅱ~1 malocclusion in growth modification.