[Bisphosphonate related osteonecrosis of the jaw and infection with Actinomyces].

Background And Objective: Bisphosphonate related osteonecrosis of the jaw (BRONJ) has raised considerable interest since its recent description. Its pathogenesis is not yet clarified; formerly it has been considered a non-infectious complication, but recent studies seem to implicate bacteria of the genus Actinomyces. The objective of this study is to analyze the cases of BRONJ in our institution.

Patients And Methods: Review of medical records of patients diagnosed of BRONJ in the Maxillofacial Surgery Unit of our hospital.

Results: We have found 11 cases of BRONJ in our hospital: 4 women taking oral alendronate or risendronate for osteoporosis and 7 cancer patients treated with intravenous zolendronic acid. All of them showed bone invasion by bacteria of the genus Actinomyces. Nine patients underwent prolonged treatment with amoxicillin with favourable clinical outcome in all of them, but 3 died of their malignancy. By contrast, one patient with beta-lactamic allergy and irregular treatment with erythromycin and tetracycline had a chronic evolution of the lesions. There was no information for other patient.

Conclusions: Actinomyces play an important role in the development of BRONJ and specific antibiotic treatment improves the prognosis of this process.