Periapical actinomycosis of the mandible: A diagnostic challenge mimicking conventional apical periodontitis- A case report.

Actinomycosis is a rare, chronic suppurative infection caused by filamentous, Gram-positive anaerobic bacteria, primarily Actinomyces israelii, with cervicofacial involvement being the most common presentation. Periapical actinomycosis, a rare central subtype of cervicofacial actinomycosis accounting for approximately 1-2% of central cases, is characterized by an indolent, less invasive course. This case report describes an unusual presentation of mandibular periapical actinomycosis in a 26-year-old immunocompetent female with no history of trauma or predisposing comorbidities. The patient presented with mobility in the lower right anterior region. Clinical and radiographic examination revealed a non-vital tooth #41 with associated lateral radiolucency and significant alveolar bone loss, initially suggestive of conventional apical periodontitis. Following endodontic treatment, surgical debridement uncovered a yellowish exudate, prompting a biopsy. Histopathological examination was pivotal, revealing chronically inflamed granulation tissue with characteristic colonies of filamentous, branching bacteria consistent with Actinomyces species, confirming the diagnosis. The lesion was successfully managed with a combination of thorough surgical debridement, bone grafting (β-TCP), placement of an amniotic membrane (AM) barrier and a prolonged course of antibiotic therapy with amoxicillin. At a 6-month follow-up, there was no evidence of recurrence. This case highlights the diagnostic challenge posed by periapical actinomycosis, which can closely mimic common endodontic diseases and neoplasms. It underscores the indispensable role of histopathological evaluation in reaching a definitive diagnosis and the importance of considering this infection in the differential diagnosis of refractory periapical lesions.