A 64-year-old male patient seeking to have his missing posterior teeth restored with dental implants came to the Department of Periodontics, Gangneung-Wonju National University Dental Hospital. The patient had arrhythmia, hypertension, rheumatoid arthritis, and blood coagulopathy and described that he lost the posterior teeth seven years ago by accident. Four cylindrical endosseous implants were placed by two staged approach on left and right mandibular second premolar and first molar areas (Fig. 1). Healing was uneventful and second stage surgery was done 3 months later. At the time of second stage surgery, periapical radiographs revealed a radiolucency at the apex of the implant of the mandibular right first molar area (Fig. 2). Although there was neither clinical symptom nor functional problem, the radiolucency has continued to exist up to the most recent twelve year-follow up (Fig. 3 - 5). No treatment was done in this case.

A 53-year-old male patient presented with a tooth having severe dental caries which was not restorable in the area of right mandibular first molar. The tooth had previous endodontic treatment and right mandibular second molar was missing. It was planned to extract the tooth and to place two implants in the mandibular right first molar and second molar area. Extraction was accomplished and healing occurred without incident. About three months after the extraction, two implants were placed by two staged approach (Fig. 6). Two weeks after the first stage surgery, the patient presented with a complaint of pain. Clinical examination revealed no tenderness to palpation, no fistula, no significant probing depth, and an apparently stable implants on both sites. However, a periapical radiograph revealed a radiolucency at the implant of mandibular right first molar site (Fig. 7). The patient had been under the systemic antibiotic therapy for three weeks until the clinical symptom disappeared. Four weeks after the surgery, pain subsided in spite of the size of radiolucent lesion increased (Fig. 8). It was planned to be checked up regularly because there was no symptom. Second stage surgery was done 4 months after the first stage surgery and the stability of involved implant was identified (Fig. 9). Though the periapical radiolucency still existed at the time of the placement of implant prosthesis (Fig. 10), the five-year follow up radiograph demonstrated its complete disappearance (Fig. 11).

A 45-year-old female patient was seen with a fractured tooth due to severe dental caries in the area of left mandibular first molar. Four months after the extraction, implant was placed by two staged approach showing good initial stability at the time of surgery (Fig. 12). Three weeks later, the patient complained of pain on surgical area. Clinical examination revealed that adjacent second premolar was positive to percussion with no other clinical findings specifically. However, periapical radiographs showed a radiolucent lesion around the apex of the implant and the periodontal ligament widening of the adjacent mandibular left second premolar (Fig. 13). The patient had systemic antibiotic therapy for two weeks, which leaded to decreasing of pain five weeks after the surgery. Considering the size of IPL had increased on a radiograph and still remaining discomfort, however, surgical approach was chosen (Fig. 14). The surgical protocol comprised total debridement with the additional removal of the possibly infected apical portion of bone. During the surgery, implant stability test by resonance frequency analysis was performed and indicated significant mobility of implant fixture. Thereafter, a decision was made to remove the implant (Fig. 15). The specimen from the lesion was fixed in 10% buffered formalin, processed to obtain thin ground sections and stained. The histological examination showed the infiltration of chronic inflammatory cells without any signs of bacterial invasion. Three months after the explantation, implant was replaced by one stage surgery showing to maintain good stability without any complication (Fig. 16) by the time of the six-year follow up (Fig. 17).