Craniofacial hard tissue changes with the modified Twin-Block appliance for treating the children with Angle Class II division 1 malocclusions

AIM: To evaluate the craniofacial hard tissue changes with the modified Twin-Block functional appliance in the treatment of Angle ClassⅡdivision 1 malocclusions in children. METHODS: Nineteen patients in growth with Angle Class Ⅱ division 1 malocclusion presenting mainly with mandibular retrognathia were treated with the modified Twin-Block appliance. Lateral cephalometric radiographs were taken before and after treatment for observing hard tissues. RESULTS: After the treatment with modified Twin-Block functional appliance, SNB angle, Co-Pg were increased significantly (P0.01). The mandible development was boosted, while the effect of restraining the maxilla was not in evidence. The change in SNA angle was not significant. There were no changes in A point. The upper first molar was displaced distally(P0.05)and the lower first molar was displaced medially(P0.01). The labial inclination was found in lower incisors (P0.01).The vertical distance, ANS-Me and Ar-Go were increased significantly (P0.01). CONCLUSION: The modified Twin-Block functional appliance can accelerate the mandible development efficiently. It can improve the lateral retrognathic profile and rectify the mandibular retrusion.