This paper presents a case of purulent peri-implantitis at an implant in the maxillary right lateral incisor position. The lesion was unresponsive to close debridement and, thus, open flap surgery was performed. Profound bone loss was evident around the implant and a retained retraction cord at the cervical portion of the implant was observed. Treatment included a sequence of decontamination steps and guided bone regeneration with the aim of eliminating the etiology and enhancing implant survival. In the presented case, it can be speculated that the retraction cord served as a plaque retentive factor which ultimately led to bacterial accumulation and periimplant disease. Thus, it is crucial to ensure that no plaque retentive factors (cement remnants, retraction cord, ill-fitting margins of crowns, etc.) are present when restoring an implant. Plaque retentive factors might result in a destructive effect on the peri-implant tissues and bone. Schlagwörter: bone loss, dental implants, iatrogenic damage, plaque retentive factors, regeneration, suppuration