Osteonecrosis of the posterior mandible after implant insertion: a clinical and histological case report.

Background: In the past few years, the occurrence of an oral lesion, called osteonecrosis of the jaw (ONJ), has been increasingly reported in patients undergoing treatment with bisphosphonates (BPs); however, few published histological studies of ONJ can be found in the literature. Purpose: The aim of the present case was to report an occurrence of ONJ after implant insertion. Materials and Methods: Multiple myeloma was diagnosed to a 65-year-old female. After 5 years of treatment with intravenous clodronate, two dental implants were inserted in the mandibular molar region. No preexisting bone lesions were present at a preoperative panoramic radiography. Before implant insertion, the patient had suspended the treatment with clodronate for 3 months. Four months after the implant insertion, a breakdown of the oral mucosa covering the implants occurred with a purulent discharge; periapical radiolucency was present around both implants. An en-block resection on the alveolar bone including the two implants was performed. No signs of recurrence of the lesion were observed after a follow-up of 20 months. Results: At the interface of one of the implants, a gap was observed between bone and implant. This bone was nonvital, and many osteocyte lacunae were empty. Moreover, this bone appeared to be partially demineralised. No newly formed bone or osteoblasts were present. Bone trabeculae were observed, on the other hand, within the apical implant threads of the other implant. A close connection was observed between this bone and the implant surface. Discussion: The histological findings showed some areas with osseointegration in patients undergoing BP treatment for malignant disease; however, any invasive procedure can determine the onset of osteonecrosis. Conclusion: In conclusion, there is certainly a temporal association between BP use and development of ONJ, but a correlation does not necessarily mean causation. Moreover, generalizations about this complex relationship cannot be made on the basis of a single case report. In patients undergoing intravenous treatment, clinicians must be aware of the increased risk of implant failure and, probably, implant insertion should be avoided at all until more conclusive data are available.