Systemic inflammatory host response to periodontopathogenic bacteria in the oral cavity: from experimental to clinical studies

Periodontal diseases are one of the most common complex infections in humans and many other mammals. Infectious agents causing periodontitis are primarily periodontopathogenic bacteria, but disease pathogenesis and progression are immune-mediated. Local inflammation is well characterized, and experimental animal models of periodontitis have also provided mostly consistent data on systemic inflammatory host response. However, the data from the clinical studies are more variable, especially when obtained from patients post treatment. The variation observed may be a result of the model employed or bacterial species tested with a particular emphasis on monoinfections as compared to coinfections and periodontitis, and individual host response. Experimental animal models also mostly lack the variable extent, severity of periodontitis, and the truly chronic nature of the naturally occurring chronic periodontitis. These shortcomings can at least in part explain some of the discrepancy between experimental and clinical data.