A case of extensive crown fracture associated with intrusion of the permanent maxillary central incisors in an 8-year-old boy is reported. The treatment of both injured teeth included attempts of apexification and arrest of root resorption with calcium hydroxide. After 8 months of the trauma, there was no calcified barrier formation in the apex. Mineral trioxide aggregate (MTA) was then used as a filling material. At 15-month follow up, the teeth were asymptomatic and correctly sealed, the external inflammatory root resorption had stopped, and the radiolucent image had disappeared, which meant the initial healing of the periapical lesion. MTA may be considered as an alternative option for the treatment of traumatized and immature permanent teeth.