The actual relationship between periodontal and pulpal disease was first described by Simring and Goldberg in 1964. Since then, the term "perio-endo" lesion has been used to describe lesions due to inflammatory products found in varying degrees in both the periodontium and the pulpal tissues.Endodontic-periodontal lesions present challenges to the clinician as far as diagnosis and prognosis of the involved teeth are concerned.Treatment and prognosis of endodontic-periodontal diseases vary and depend on the cause and the correct diagnosis of each specific condition. This book presents a review on pathogenesis of endo-perio lesions and their differential diagnosis. It also presents a study on role of non-surgical endodontic treatment as a sole treatment in management of endo-perio lesions. It also emphasizes on importance of long term follow-up in managing of such cases.