RESUMO
Introduction: Paraendodontic surgery is a safe and adequate alternative when teeth are not responding to conventional treatment and endodontic re-treatment. It must only be applied in specific situations. Endodontic treatment failures can be related to: extraradicular infections such as periapical actinomycosis; to foreign body reactions that can be caused by endodontic material extrusion; to endogenous cholesterol crystal accumulation in apical tissues; and unresolved cystic lesion. Paraendodontic surgery comprehends a set of procedures recommended in periapical diseases treatment, when traditional endodontic therapy does not obtain favorable outcomes. Objective: To report a clinical case where an apicoectomy was indicated due to failure in conventional endodontic treatment. Case report and Conclusion: Clinical case report of a tooth with unsatisfying conventional endodontic treatment history, due to lack of treatment in fourth root canal and an unsuccessful apicoectomy, since the lesion and the fistula had persisted. It was chosen to retreat tooth #26 and perform a new apicoectomy in the mesiobuccal root. The treatment was successful due to absence of fistula and painful symptoms and due to periapical bone repair.