Effect of improved Twin-Block appliances on the treatment of class II division 2 malocclusion

Objective To evaluate the dento-alveolar,skeletal and soft tissue changes caused by Class Ⅱ division 2 malocclusion correction in the patients treated with improved Twin -Block appliance. Methods Nine patients in growth with Angle class Ⅱ division 2 malocclusion and mainly with mandibular retrognathia were investigated.Lateral cephalometric film indicated the growth accelerated phase,Lateral cephalometric film and skeletal,dento-alveolar and soft tissure measurements were carried out before and after treatment for each patient.Two time-points of results were compared and submitted to statistical analysis. Results All patients proved to be co-operative and treatment pro- gressed well.Overall a satisfactory occlusal result and appearance have been achieved. SNB,mandibular plane angle were increased by 4.2°and 3.0°,respectively(P0.05).The interincisal angle was decreased by 15.5°(P0.05),ANB was decreased by 3.4°(P0.01). 1/NA,1/SN were increased by 15.5°and 17.9°,respectively (P0.01). Conclusion Im- proved Twin-Block functional appliance possesses theorthopedic effect on Angle class II division 2 malocclusion.When repositioning the mandible forward.All the aspects contribute to a harmonious relationship of upper and lower jaws and a better profile.