The Function of the Oral Microbiome in Health and Disease

It is now well established that the oral microbiome plays a critical role in the health status of not only the oral cavity but other body sites away from the mouth. A transition from a commensal to a pathogenic oral microbiome causes an imbalance of oral homeostasis, a phenomenon called dysbiosis, which is a crucial concept to understand most oral diseases. In the present chapter, we briefly summarize the current knowledge on the function that oral microbes play in health and disease. We have divided the chapter into three major sections. In the first section, we cover the oral microbiome in health, where we describe the ecological forces that shape the microbial community as well as the composition and function of the commensal oral microbiome. In the second section, we focus on the transition from a commensal to a dysbiotic microbiome in the major oral diseases: caries and periodontal diseases. Finally, in the third section, we describe the role of members of the oral microbiome in systemic diseases, including cardiovascular disease, cancer, and adverse pregnancy outcomes.