Actinomyces sp. Presence in the Bone Specimens of Patients with Osteonecrosis of the Jaw: The Histopathological Analysis and Clinical Implication.

Medication-related osteonecrosis of the jaw (MRONJ) and osteoradionecrosis (ORN) are two similar bone pathologies in the jaw with different aetiologies. Actinomycosis is a relatively rare oral infection caused by the Gram-positive anaerobe Actinomyces sp. that normally colonizes the oral cavity. Actinomycosis is associated with the pathogenesis of both the MRONJ and ORN, as evident in our cases, and not just as a superficial contaminant. The clinical and histopathological aspects of the cases treated in our centre were also reported with a review of the literature. Clinical implication on the treatment of the cases was highlighted in view of the presence of this microorganism.