The clinical spectrum of Actinomyces-associated lesions of the oral mucosa and jawbones: correlations with histomorphometric analysis

Objectives: To characterize the clinical manifestations of Actinomyces-associated lesions of the oral mucosa and jawbones, and to correlate the clinical course and treatment requirements with the findings of histomorphometric analysis. Study design: The study was a 10-year retrospective analysis of archived cases with microscopic identification of Actinomyces infection. Actinomyces colonies were identified, using hematoxylin-eosin, Gram, and periodic acid-Schiff stains, exhibiting filamentous morphology with color variation between center and periphery. Only colonies with adjacent tissue reaction (inflammation, fibrosis) were analyzed. Actinomyces density (AD) was calculated by dividing total number of colonies by tissue surface, Actinomyces relative surface (ARS) was calculated by dividing total bacterial surface by tissue surface. Results: The study included 106 cases (48 male, 58 female; aged 13-84 years, mean 50.5 years). Cases presented a wide clinical spectrum, involving jawbone and/or oral soft tissues. Cases included osteomyelitis associated with bisphosphonates, osteoradionecrosis, osteomyelitis unrelated to radiation or bisphosphonates, periapical lesions, odontogenic cysts, periimplantitis, and lesion mimicking periodontal disease. The AD correlated with median length of antibiotic treatment (R = 0.284; P = .028). Conclusions: Because we were able to identify 106 such cases, the results indicate that Actinomyces-associated lesions may not be as rare as would be expected from the relatively low number of cases in the literature. Actinomyces-associated lesions presented in a wide spectrum of clinical settings and a variety of contributing factors. Quantitative analysis of the number of bacterial colonies (representing bacterial load) could help in evaluating the aggressive potential of the lesion and help in treatment planning.