The embryonic root groove is an anatomical abnormality that starts in the cingulum and extends longitudinally down the long axis root towards the apex. This developmental anomaly is more frequently reported in maxillary lateral incisors. Gu YC in 2011 established three types of radicular grooves depending on its severity. According to this classification, type III presents a greater diagnostic and therapeutic complexity. The prevalence of palatogingival grooves in maxillary lateral incisors ranges from 1.9 to 14%. This case report provides valuable information about the diagnosis and treatment plan of palatogingival grooves with Cone-beam computed tomography (CBCT) scan. The patient was referred to the University Dental Clinic of European University of Valencia, with recurrent abscesses at the upper right lateral incisor region for the last two years. Palpation and percussion tests were positive for tooth 1.2. There was no clinical history of caries or previous trauma. Periapical radiography showed periapical radiolucent lesions located, not only in the apical area of tooth 1.2, but also in tooth 1.3. Both teeth had previously been endodontically treated. Periodontal probing showed normal values. CBCT scan was perfomed in order to establish a definitive diagnosis and appropriate treatment plan. The complex anatomy of the palatal root groove requires detailed knowledge of the internal root morphology for endodontic treatment success. This complementary tool allows a more accurate image of hard tissue structures, such as palatal grooves and/or accessory roots, in comparison to conventional periapical radiography. The treatment plan of this primary periodontal lesion with secondary endodontic involvement was as follows: periapical surgery combined with root amputation and sealing with MTA, and guided bone regeneration.