Regenerative Endodontic Procedure (REP) of a Previously Treated, Infected, Immature Permanent Incisor.

The management of immature permanent teeth with pulpal necrosis and prior endodontic failure remains clinically challenging due to incomplete root development, persistent infection, and reduced structural integrity. Regenerative endodontic procedures (REPs) offer a biologically driven alternative to apexification; however, their use in retreatment scenarios is not well documented. This report describes the successful treatment of a previously treated immature maxillary central incisor in a 7-year-old patient presenting with a chronic apical abscess and a longstanding sinus tract. Prior endodontic therapy was inadequate, with insufficient obturation and a poorly adapted full-coverage restoration contributing to coronal leakage and reinfection. Management involved removal of the existing root filling material, limited mechanical instrumentation, chemical disinfection with low-concentration sodium hypochlorite, placement of a triple-antibiotic paste, and subsequent induction of intracanal bleeding. Mineral trioxide aggregate was placed over the resulting scaffold, followed by definitive coronal restoration. Clinical and radiographic evaluations at 3, 12, and 34 months demonstrated complete resolution of apical pathology, absence of clinical symptoms, increased dentinal wall thickness, and continued root maturation with apical closure. This case supports the potential application of regenerative endodontic therapy in previously treated immature teeth with persistent infection. Establishing conditions favorable to biologic healing may allow preservation of regenerative capacity even in retreatment contexts. Further investigation is needed to clarify indications, predictability, and long-term outcomes of REPs in similar cases.