There are morphological, functional, and developmental roots to the link between the periodontium and pulp. The growth of ectomesenchymal cells produces the dental papilla and follicle. The importance of this communication and its implications for the onset of the disease and subsequent treatment must be understood by clinicians. Therefore, in this study, we will evaluate the appropriate literature discussing periodontal-endodontic lesions. From 1990 to 2021, the PubMed database was searched for relevant articles using the following keywords: “combined periodontal-endodontic lesion”, “periodontal treatment”, “root canal therapy”, “combined lesions”, and “perio-endo lesion”. Several etiologic factors have played a role in the development of endodontic and periodontal diseases. However, it has been suggested that the most plausible cause is the idea of microbial participation. After periodontal disease causes various pathological abnormalities in the pulp, which are aided by lateral or auxiliary canals, bacteria develop plaque on the denuded root surfaces. Finally, physicians must understand that endodontic treatment is more predictable than the two diseases in periodontal–endodontic lesions. However, the successful completion of periodontal therapy is a prerequisite for the success of endodontic treatment. For successful long-term results, both viewpoints of periodontal and endodontic disorders must be treated comprehensively.
