Class II Division I Treated with Twin Block Appliance: A Case Report.

A 10-yearfemale presented a skeletal Class II relation with 7mm of overet, 40% overbite, and bilateral posterior lingual crossbite. Two phase therapy was planned to correct Class II skeletal relation, overjet, overbite, and achieve lip competency. Phase I therapy was done with Twin Block appliance to advance the retrognathic mandible. Phase II therapy was accomplished with fixed appliance for arch coordination, to correct minor displacement, and to finalize occlusion. Post treatment skeletal Class I relation was achieved. Incisors inclination was improved, ideal overjet and overbite with bilateral class I molar relationship was achieved. As the mandible advanced, lip competency, facial convexity, and mentolabial sulcus improved.