Gram-Positive Anaerobes in Periodontal Pathogenesis:

Advances in molecular research and the oral microbiome [3] study have depicted the number of oral bacteria (cultivable and not) to a mind-boggling 700 species! The subgingival biofilm is the primary etiology of periodontal disease initiation and progression and for this reason periodontal microbiology has been the focus of research over centuries. It has gone through paradigm shifts of ideologies over the past century such as the non-specific/specific plaque hypotheses, the ecological plaque hypothesis and recently the PSD model. The “Non-Specific Plaque Hypothesis” proposed by Black and Miller in the late 1800s, believed that the total microflora could lead to disease. The “Specific Plaque Hypothesis”, which followed in 1976 concluded that only a few species of the total microflora are actively involved in disease taking into account differences in virulence among bacteria. The “Ecological Plaque Hypothesis” put forward by Marsh [4] in 1994, emphasized that periodontal disease is the result of an imbalance in the microflora by ecological stress resulting in an enrichment of certain diseaserelated micro-organisms. “Keystone-Pathogen Hypothesis” in 2012 [5] proposes that certain low-abundance microbial pathogens can cause inflammatory disease by interfering with the host immune system and remodeling the microbiota.