Chapter 9 - Metagenomics: Implications in Oral Health and Disease

Abstract

In their mouths, humans contain millions of microbes and their genes, which together constitute the oral microbiome. Oral microbes appear to be one of the important determining factors of human health. Although, most of them perform essential biological functions that impede colonization by pathogens or correlate with our physiological needs, their dysbiosis leads to oral diseases. Recent studies have disclosed that oral bacteria can trigger a progression of systemic diseases like cardiovascular disease, stroke, rheumatoid arthritis, respiratory tract infection, colorectal cancer, inflammatory bowel disease, diabetes, etc. Therefore, a thorough understanding of the oral microbiome is necessary to gain insights into probiotics and develop therapeutics to extinguish oral pathogens. Until recently, the functions of oral microbiota remained largely out of sight because microbiota assessments were based on in vitro cultivation. The practice of cultivating and isolating microorganisms remains unsatisfactory, as most of the microbial communities cannot be grown under laboratory conditions. However, the recent burgeoning field of metagenomics has transfigured the realm of classical microbiology and has succeeded in unraveling the overwhelming diversity of oral inhabitants, their tremendous genetic and metabolic repository with unprecedented speed and accuracy. This chapter provides a robust introduction to oral specific commensals and pathogens, composition of the oral microbiome, and their implications in enhancing health and developing various diseases.