Dental implants are the norm of today’s dentistry and are the answer for replacement of both missing tooth/teeth and edentulism. A factor of concern during treatment planning is the pulpal and peri – radicular condition of teeth adjacent to the implant site. Peri – radicular pathosis may initiate implant periapical lesions (IPL) which subsequently jeopardize the dental implant. IPL is the infectious – inflammatory process of the tissues surrounding the dental implant apex interface. This case report presents a case history related to IPL, which was caused by a pre-existing endodontic lesion from the adjacent tooth. Diagnosis is achieved by studying the presence of signs and symptoms such as pain, swelling, suppuration or fistula and radiographic examination. A diagnostic classification is proposed to establish the stage of the lesion, and determine the best treatment option accordingly. The aim was to report the success of treating IPL which was caused by the presence of radicular cyst from neighbouring infected tooth.