Boring bacteria: a morphological research on bone diagenesis.

Post mortem interval (PMI) estimation is a crucial issue in forensic medicine. To date, little is known about factors affecting post-mortem changes in hard tissues and it is still unclear who between exogenous bacteria from the environment and endogenous microbiota is the cause of microscopical alterations observed in human bone after death. Recent research highlighted an important role of endogenous bacteria in the earlier stages of the process. The aim of this study was to probe a potential endogenous model of human bone biodeterioration, based on the action of oral cavity endogenous microorganisms. A total of seventy-four fragments of human bone samples were incubated with six bacterial strains, isolated from human tartar specimens. In a forty-eight months long prospective study, the onset and development of bone tissue alterations were serially analysed by scanning electron microscope. The research furnished evidence that endogenous bacteria are able to bore into human dead bone, giving rise to microstructural changes morphologically indistinguishable from those observed in archaeological and forensic bones