Endodontic overfills and incomplete obturation is usually associated with an array of local complications and results in persistent periapical infection and inflammation. In addition, imprecise management of immature roots also leads to treatment failure. Here, a case of open apices of maxillary central incisors with extrusion of Gutta-percha and associated large periapical lesion is presented. Mineral trioxide aggregate (MTA) was used to obturate the blunderbuss canals, and an alloplastic graft (biphasic calcium phosphate) was filled in the bony defect after surgical curettage. At the 6th month postoperatively, periapical osseous healing was satisfactory. The advantages and indications of MTA as obturation material and bone graft in periodontal regeneration are discussed. Clinically and radiographically, the case was followed for 5 years to assess the outcomes of MTA obturation.