This report describes the 24-month clinical and radiographic outcome of an unintentionally extruded mineral trioxide aggregate (MTA) apical plug. A 9 year old boy presented with a previously traumatized, immature central incisor; associated with a large periradicular lesion. During placement of MTA in the treatment of wide open apex, the material was inadvertently extruded into the periapical region upon a sudden movement of the child. No intervention was made, except for obturation of the remaining root canal two weeks later. The radiographic follow up at 12 and 24 months confirmed successful management through the non surgical approach, as evidenced by advanced healing of the periapical lesion and regeneration of the periradicular tissue in the absence of clinical symptoms.