The objective of this clinical case report is to demonstrate the importance of the origin of an endodontic lesion, to know how to diagnose it correctly, as well as to work in a multidisciplinary way to arrive at a correct treatment plan. In this case, guided tissue regeneration is an excellent treatment option for intrabony defects. Case Report: 42-year-old female patient, healthy, attends the clinic of the Master of Periodontology of the Faculty of Dentistry of the Autonomous University of Coahuila, being referred from the endodontics department, since she presented injury to the dental organ left upper lateral incisor which had previously been treated endodontically, with a diagnosis of pulp necrosis, medicating intra canal with pure calcium hydroxide on two occasions, without presenting improvement, for which a computed tomography scan of the involved dental organ was requested, since the lesion did not subside and presented signs of inflammation, pain on percussion, with a periodontal probing greater than 8 mm and grade II mobility, for which it was decided to perform exploratory surgery, debriding the surrounding region of dental organ left upper lateral incisor, presenting a palatal groove that extended towards the cervical third of the root, it was decided to perform guided tissue regeneration, since the defect was contained, using autologous and alloplastic bone graft, as well as or platelet rich fibrin membrane, temporarily placing a dental splint to keep the teeth fixed. Result: A monthly radiographic study (periapical radiographs) was performed to assess the previously treated endodontic lesion and assess the greater amount of hard tissue formed in the periapical area of dental organ left upper lateral incisor and eliminating dental mobility, as well as pocket depth, taking the tooth to periodontal health.