Oral Microbiota: Findings, Classification, Clinical Significance, and Therapeutic Interventions for Human Systemic Diseases

ABSTRACT The oral microbiota is an ecological community of commensal, symbiotic, and pathogenic microorganisms that colonizes the oral cavity. It usually exists as a biofilm and to date, more than 700 species have been isolated, including bacteria, fungi, viruses, and so on. The oral microbiota is highly diverse and plays an important role in the human microbiome. However, an imbalance between the oral microbiota and the host can affect oral health and even lead to the development and progression of systemic diseases. Such imbalances are associated with many pathologic and physiologic processes, including dental caries, periodontitis, oral cancer, cardiovascular disease, neurologic conditions, gut disorders, respiratory diseases, metabolic disorders, and cancers, but the exact mechanisms underlying most of these diseases remain unknown. Here, we look back at the origins of the oral microbiota, describing its species and functions. We summarize how oral microbiota are involved in oral and systemic diseases. Importantly, we also describe advances in drug development, and present therapeutic interventions for diseases associated with the oral microbiota.