This case report presents the outcome of atypical extraction and effect of Twin Block appliance on a growing adolescent. A 12-year-old boy who had complained about protrusive upper lips after being involved in a traffic accident. Tooth 11 was replanted at a local dental clinic, while tooth 21 was lost. In extra-oral examination, this patient had convex profile, obtuse nasolabial angle, and receded chin position. In intra-oral examination, bilateral Class II molar and canine relation were shown, the overjet was 11 mm between tooth 11 and 41; 7 mm between tooth 22 and 31; the overbite was 6 mm. Cephalometric analysis showed skeletal Class II jaw relationship with mandibular retrusion, and average mandible plane angle. The cervical vertebrae maturation stage was in late stage II to stage III. In the first stage of treatment, he received partial fixed orthodontic appliance to increase the overjet; then, Twin Block was used to facilitate mandibular growth. In the second stage, full-mouth fixed edgewise appliance was bonded and teeth 11 and 42 were extracted due to poor prognosis. After treatment, a harmonious profile was achieved. With proper case selection, good patient cooperation and appropriate appliance construction, distinct result with Twin Block appliance can be achieved. Early treatment using Twin Block appliance is effective in reduction of anterior-posterior discrepancy and severity of malocclusion.

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Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.