Actinomycosis is an infiltrative disease caused by Actinomyces species that frequently has chronic granulomatous and suppurative lesions. The present case reports an adult female patient with a diffuse and atypical actinomycotic lesion which had a large desquamation and subsequent exposure of the alveolar bone in the region of the maxillary left first and second molars. Diagnosis was based on histopatholigical examination. Due to the opportunistic characteristics of the actinomycotic infection, early diagnosis of the lesion, together with the adequate therapy and management are of great importance to prevent the spread of the disease. Proper knowledge of the different types of periodontitis is essential to distinguish any atypical presentation of tissue destruction.