Endoperiodontal injury is a common condition in dental offices that, due to the complexity of clinical aspects, can induce simulations of one disease and not another, making diagnosis difficult. Faced with changes that simultaneously affect endo and periodontal tissues, the dentist must have knowledge about etiological factors, dental and orofacial anatomy, pulp and periodontal diseases, predominant pathogens, communication routes, classifications of primary diseases, primary with secondary involvement or combined, assessment techniques to -through anamnesis and intraoral and complementary exams -reach the correct diagnosis that facilitates the best outcome for the patient, whether through a therapeutic or surgical approach. The apical foramen, lateral or accessory canals, dentinal tubules devoid of cementum (due to scaling or root planning or due to congenital absence) are pathways for fluid communication to occur between the pulp and periodontium, which may contribute, for example, to the development of dental diseases. primary origin. The endodontic and periodontal relationships discussed, since 1948, by Johnson and Orban were later proven by research carried out by Seltzer and his team, when changes in periodontal tissues were found after induction of a certain endodontic condition. The present study aims to review the literature regarding the polymicrobial origin of these lesions, considering that the lack of knowledge about the respective agents contributes to mistaken diagnoses and decision-making that can lead the dentist to respond legally, even if their responsibility as an endodontist or periodontist is half. This literature review examined articles published in Portuguese and English on the platforms PubMed, SciELO, ResearchGate, Google Scholar and LILACS, between 2000 and 2023, using the DeCS descriptors in Portuguese and English "regenerative endodontics", "periapical tissue", "dental pulp diseases", "dental pulp necrosis", "regenerative endodontics", "periapical tissue", "dental pulp diseases", "dental pulp necrosis" articulated with the Boolean operators "AND", "OR" and "NOT ". Exclusion criteria include articles published outside the established period, theses, dissertations, monographs and animal studies.