The document provides a comprehensive overview of endodontic and periodontal interactions, focusing on the classification, diagnosis, and treatment of lesions involving pulpal and periodontal origins. It discusses various types of lesions that require endodontic, periodontal, or combined treatments, along with diagnostic challenges and treatment alternatives. Additionally, it addresses the effects of both pulp treatment on periodontal health and vice versa, including the influence of anatomical and pathological factors.