Osteopathology associated with bone resorption inhibitors - which role does Actinomyces play? A presentation of 51 cases with systematic review of the literature.

BACKGROUND: Bone resorption inhibitor-related osteopathology of the jaw (BRIOJ) is a severe complication in patients treated with bisphosphonates or denosumab. However, the precise pathogenesis of BRIOJ is not yet fully understood. Recent studies discovered the presence of Actinomyces colonies in biopsy material from BRIOJ patients. The aim of this study was to analyze current knowledge concerning the impact of Actinomyces on the pathogenesis of this condition and to present data from our own patients. METHODS: Data from 51 patients with histopathological diagnoses of BRIOJ were retrospectively analyzed. In addition, a systematic literature search for studies describing the presence of Actinomyces was performed. RESULTS: Actinomyces was present in 86% of our cases and 63.3% of 371 cases presented in the literature. All of our patients and 85% of patients described in the literature had a clearly defined local focus in association with osteopathology. A clear picture of whether Actinomyces colonizes the previously necrotic bone or contributes to inflammation causing subsequent bone necrosis is lacking in the literature. CONCLUSION: The pathogenesis of BRIOJ remains unknown; however, there seems to be a role for Actinomyces, and possibly other pathogens, in the development of osteopathology of the jaws, which is not exclusive to bisphosphonate therapy. This study supports the hypothesis that an infectious component is of utmost importance for the pathogenesis of BRIOJ.