Internal root resorption is not a common condition, especially in permanent teeth. It is characterized radiographically by a disruption of the canal space, typically ovoid in appearance. This article describes a unique case in which an internal resorptive defect was developed in a maxillary premolar, which had previously been endodontically treated. The use of advanced modalities such as the cone beam computed tomography (CBCT) has an important contribution in the diagnosis and hence, the clinical treatment protocol in this case. After completing non-surgical endodontic retreatment, the canals were sealed with thermoplasticized gutta percha, which remains the most favorable treatment in such cases.