Endodontic implant pathology (EIP) refers to cases in which endodontic infections cause infections in adjacent implants, and vice versa. This case report demonstrates the successful resolution of two types of EIPs, implant endodontitis and endodontic implantitis, by endodontic intervention with surgical treatment. In case 1, the patient complained of tooth discomfort after implant placement in the adjacent tooth. The tooth was sensitive to percussion and showed slight mobility with a negative reaction to an electric pulp test. The symptoms persisted despite conventional root canal treatment, and surgical treatment of the symptomatic tooth and implant lesion was performed. In case 2, the patient suffered from repeated infection around a newly installed implant. The adjacent devitalized tooth exhibited a periapical lesion that was contiguous with the implant. Conventional root canal treatment and retreatment did not successfully resolve the symptoms. Surgical root canal therapy was then performed with regenerative biomaterials as needed. Neither case showed radiographic or clinical evidence of failure after 4 and 5 years of follow-up, respectively, after the surgery and the adjacent implants were successfully osseointegrated. Endodontic intervention combined with surgical treatment resolved both types of EIPs and led to tooth preservation and successful osseointegration of adjacent implants.