Human oral microflora

Oral cavity is the first and foremost part of the gastrointestinal tract. The process of digestion starts from the oral cavity. Our food is metabolized initially in the oral cavity. Metabolism of the food substances in the oral cavity is brought about by the microflora present in different sites in the oral cavity. The oral cavity has a colony of microorganisms present even in healthy state, which when altered can lead to pathogenesis. Microbial flora is present at different sites in the oral cavity providing them habitats. This flora is classified into various categories of different species comprising of viruses, bacteria, yeasts and even on occasions, protozoa. The presence of flora is basically due to the specificity of organisms to each site which is termed as tissue specificity. The microflora exhibits tissue tropism and specific adherence responsible for the tissue specificity. The microflora present on the hard and soft surfaces exhibits biofilm formation wherein the pioneer species attach to the surface and form a network on which bacterial colonization occurs. The composition of microflora is affected by various factors such as temperature, redox potential, pH, endogenous and exogenous nutrients, innate and acquired host defence, host genetics and antimicrobial agents. Not all of the species in microflora are significant, however few species are important as they have significant role in both healthy as well as in disease state. Oral microbial species also form dental plaque, which can lead to dental caries on the tooth surface and periodontal diseases on the soft tissues of periodontium. Oral microbial species have been suggested in affecting cardiac health as bacterial endocarditis is caused by the streptococcus from the oral microflora.