Infiltration anesthesia with 2% articaine (Ultracaine DS, Sanofi Aventis Drugs, Istanbul, Turkey) was applied to the premolar area for hemostasis and for post-operative pain control. A full-thickness vestibular flap was elevated gently, and surgical tooth extraction was performed using surgical burs with straight elevators. Surgical wounds were closed with 3/0 vicryl sutures and streptomycin 0.5 g/day was administered for 3 days postoperatively. After the extraction, a 3-month period was allowed for healing of the alveolar bone and soft tissue (Fig. 2).

After the 3 month healing period, a second surgery was performed for implant insertion. Pre-surgical procedures were the same as those described above. In addition, a horizontal incision was made along the edentulous premolar area. A mucoperiosteal flap was gently elevated to expose the recipient bone and the implant sockets were prepared using a commercially available surgical set (Straumann® instruments, Straumann AG, Waldenburg, Sweden) under sterile saline irrigation. All the implants had a sandblasted and acid-etched (SLA) surface and were of the same size and length (3.3 × 10 mm, tissue level). All implants were inserted to the level of the machined surface left below the bone. Non-submerged healing protocol was performed in all the groups and the flaps were closed with 3/0 vicryl sutures.

In group 1, after the insertion of the implants, 3/0 silk sutures (Doğsan, Trabzon, Turkey) were placed below the free gingival/mucosal margin around the implants and plaque control was terminated for 2 months (Fig. 3). To promote plaque retention and peri-implantitis, the animals were fed a soft diet. The implants were removed with reverse torque after the induction of peri-implantitis (Fig. 4). After the removal, all the implant surfaces were cleaned by air-flow with bi-carbonate granules for 1 min prior to the treatment with citric acid (pH: 1).