Internal root resorption (IRR) is a rare pulp disease. Its etiology involves late pulpal inflammations and trauma, among others. IRR may also show some symptoms, and is usually detected by X-rays. However, its diagnosis is significantly improved by the use of cone beam computed tomography (CBCT). The objective of this case report was to account for the diagnosis and management of an internal root resorption without perforation. The patient, a 26-year-old male, went to the School of Dentistry at Universidad Andres Bello, Concepcion, without having symptoms in the tooth 1.1. Anamnesis revealed the presence of previous symptoms. CBCT examination showed absence of bowl-shaped calcified dentin tissue on the inner walls of the root canal with apical lesion but without perforation of surrounding tissues. Endodontic treatment was performed using the following methods: irrigation of the root canal with 2% chlorhexidine (CHX) using a Max-i-probe cannula and simultaneous cavitation of the irrigant Then calcium hydroxide (CH) was applied as intracanal medication for a week and Schilder’s technique for vertical compaction was used. The patient was checked after one week and then after six months. He did not have any symptoms. Early diagnosis using modern imaging equipment, appropriate use of ultrasound for chemomechanical debridement and thermoplastic filling techniques contribute to a more favorable prognosis of patients with internal root resorption.