Root resorption (RR) is the loss of dental hard tissues as a result of clastic activities. Internal inflammatory root resorption (IRR) is a type of RR characterized by progressive loss of tooth substance starting from the root canal wall. IRR is usually asymptomatic, slowly progressing, and detectable upon routine radiographic examination or by the clinical sign of a ‘pink spot’ when the IRR involves the crown or the coronal third of the root canal. Mineral trioxide aggregate (MTA) is a biocompatible cement that has been used successfully in pulp capping, pulpotomy, treatment of traumatized teeth with immature apices, and for treatment of root resorption. The treatment and follow-up of a maxillary central incisor with perforating IRR managed by root canal treatment and grey MTA repair is reported. IRR affected tooth 11 (FDI World Dental Federation) in a 29-year-old female patient, with a history of previous trauma. Follow-up radiographs over 24 months demonstrated the maintenance of a functional tooth. However, the tooth showed a green discoloration of the crown after MTA treatment.