As long as the prognosis of teeth remains a matter of concern, the endodontic-periodontal relationship will be considered a challenge for the clinician. Many etiologic factors, including bacteria, fungi, and viruses, plus other contributing factors, such as trauma, root resorptions/perforations, and dental malformations, play a role in the co-occurrence of endodontic and periodontal lesions. Whatever the cause, a correct diagnosis on which to base the treatment plan is the key to successful maintenance of the tooth. This article reports the successful endodontic management of a furcation lesion in a mandibular molar that was nonresponsive to a previous periodontal surgical graft. The case had presented a diagnostic challenge for the clinicians, and this article reviews the key points that can lead to a correct diagnosis and treatment planning.

A tooth with primary endodontic disease that demonstrates a periodontal defect might be extracted because of misdiagnosis as severe periodontal disease or a vertical root fracture. The aim of this case report was to demonstrate the long-term survival of endodontically treated teeth, which had been initially considered unsavable. With meticulous evaluation including the patient's dental history, clinical and radiographic examinations, teeth with primary endodontic lesions could be differentiated and saved after proper root canal treatment. Pain history, vitality test, and radiographic examinations, as well as a general periodontal condition check with periodontal probing on an affected tooth, might be the key methods to differentiate endodontic pathosis from that of periodontal disease.