| case report Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 7: Pre-operative situation. Figs. 8 & 9: Control radiographs of two implants placed in regions #35 and 36 on the day of implantation. Fig. 10: Situation in regions #34 to 36: seven days after endodontic treatment. The patient was free of complaints. (iatrogenic reasons, poor planning), they should be treated immediately. Thus, some studies have reported cases in which no bacteria were found on the surface of the explanted implant after occurrence of RPI.2, 4 Stage 2 If the lesion persists, established empirically from the oral surgery, the apex should be exposed. If the lesion is of Class 1 or 2 and the implant is stable, loaded or not, it should not be removed immediately. Surgical intervention from the lateral side should be performed if osseointe- gration has already occurred. Resection of the implant apex, depending on the extent of the lesion, can reduce the survival rate of the implant. The surgical procedure can be standard, rinsing with an antibacterial solution, application of local anaesthetic, curettage, administra- tion of anti-inflammatory medicaments, drainage, etc. At the same time, we provide the patient with systemic an- tibiotic treatment accompanied by low-dose glycocorti- costeroids or mefenamic acid. Some authors advise aug- mentation of the defect and flap closure; we believe this decision is not mandatory, but depends on the findings at the implant apex. Stage 3 If clinical symptoms and patient complaints disappear, we advise augmentation of the surgical access and cov- erage with a membrane. At this point, Mohamed et al. report expecting a higher success rate when resection of the implant apex is performed; however, in their study, they evaluated only loaded implants and the augmenta- tion was performed with xenografts.5 Resection of the implant apex can be an assistive step for Class 3 le- sions to reduce the lesion when the thread design is not favourable for decontamination. Nevertheless, this pro- cedure is of high risk for implant stability and removal of debris from the cavity. If at this stage of the therapy, the patient still has complaints, the implant should be removed. Stage 4 As long as the apical translucency is no longer evident and the patient has no complaints, implantation can be performed. If primary stability cannot be achieved, guided bone regeneration should be performed. If symptoms or complaints cannot be controlled or the risk is high, one should wait for full bone healing, approximately six months, and plan for late implant placement. Delayed immediate implant placement seems to make no sense at this stage. A treatment protocol is provided by Kishnani et al.6 In general, the treatment of RPI or PIL relies on our experience and depends on the radiographic and clin- ical findings. Evident perforation of the buccal plate, compromised blood perfusion at the implant site and reduced primary stability describe a totally different sit- uation with a different treatment protocol. Also, an as- sociation with the Epstein-Barr virus is a matter of cur- rent discussion. Treatment success rate Studies report success rates of 46 per cent over four years.7 Resection of the apex in cases of high primary sta- bility and a lack of complaints seems to improve the suc- cess rate. The existing data is not sufficient to draw specific conclusions or evaluate treatment therapies. The reported success rates have also not been confirmed and do not differentiate between classification, symptoms or findings for the treatment applied. All data at this time is very limited. Case presentation The cases in this article concern both PIL and RPI le- sions. In the first case, the diagnosis was RPI due to in- flammation of the adjacent tooth. The second case was diagnosed as PIL without evident cause, but contamina- tion via the adjacent tooth was suspected. Both cases were late implantations without the need for bone aug- mentation, had entailed submerged healing, re-entry after four months and fixed prostheses. Both sites had been edentulous for nine to 15 months. At the time of implant placement, no pathological findings were made. Both cases were guided; the planning was assisted with cone beam computed tomography (CBCT). All prelimi- nary and intraoperative planning and control aim at pre- 18 3 2018