A 66-year-old woman was referred to the Oral and Maxillofacial Surgery Clinic at Hyogo College of Medicine Hospital, Japan, in September 2011, for an extraoral fistula and refractory pain of the right mandible associated with a purulent discharge and soft tissue swelling. The patient’s osteoporosis was diagnosed in 2005 and treated with 35 mg of alendronate weekly by the family doctor. The patient had a past history of severe osteoporosis, multiple vertebral fractures, and renal failure. She had taken 20 mg of prednisone for 3 months from 2005 for the treatment of IgA nephropathy.

Dental implant treatment in the maxilla and mandible was begun in June 2009 by the family dentist. Five implants (Spline Twist implant, Zimmer Dental, Carlsbad, CA) were placed at the same time in the posterior region of the mandible. The surgical procedure was uneventful, and primary stability of the implants was achieved. In September 2010, at the time of implant reopening for the second surgery, the implants had integrated and the healing abutments were connected. Provisional maxillary and left mandibular prostheses were cemented onto the abutments.

Nine months after the second surgery in June 2011, the patient started to complain of a painful cheek swelling on the right side of the mandible, associated with gingival bleeding. She was prescribed oral antibiotics by her dentist and underwent occasional antibiotic therapy thereafter.

In September 2011, the patient was referred to our clinic because her symptoms were getting worse. Clinical examination revealed an intraoral fistula on the lingual side of the dental implant replacing the right mandibular first molar, associated with mucosal inflammation and a purulent discharge (Fig. 1a, b). She also had hypoesthesia of the right lower lip. The patient underwent panoramic radiography (Fig. 2a) and computed tomography (CT), which showed bone resorption around the dental implant in the right mandibular first molar area and severe peri-implantitis in the right mandibular molar region. There was no obvious sequestrum separation (Fig. 2b, c). Under a clinical diagnosis of perimandibular inflammation and peri-implantitis, conservative treatment consisting of local irrigation and use of antibiotics was implemented. Meropenem hydrate was given initially, then changed to ampicillin/sulbactam. The inflammatory state improved, and when the symptoms subsided, treatment with clarithromycin was continued. Debridement and removal of the dental implant in the right mandibular first molar area was performed under local anesthesia. Irrigation of the site was continued as part of the treatment regimen.