The oral cavity houses a complex community of microorganisms known as oral microbiota, which plays a crucial role in human health and disease. This paper provides a comprehensive analysis of its composition, functions, and impact on systemic health and its association with various diseases.

Introduction

The human oral cavity is one of the most densely populated regions in terms of microbial communities, containing over 700 species, primarily bacteria, but also fungi, viruses, and archaea [9]. The oral microbiome contributes significantly to various physiological processes, including digestion, metabolism, and immunity.

By comparing the healthy states with pathological conditions, we underscore the significance of maintaining a balanced oral microbiome for overall health.

Composition of oral microbiota

The oral microbiota is dynamic and influenced by various factors, including age, diet, oral hygiene, and environmental influences. The primary genera found in the oral cavity include Streptococcus, Actinomyces, Porphyromonas, Fusobacterium, and Veillonella [2].

Healthy oral microbiota

In a healthy state, the oral microbiome is characterised by a diverse microbial community that maintains homeostasis and prevents the overgrowth of pathogenic organisms. Key functions of a balanced oral microbiota include:

1. Protection against pathogens: Healthy microbiota compete for resources and space, preventing pathogenic bacteria from establishing.
2. Metabolism of nutrients: Microbiota aids in the breakdown of complex carbohydrates and the production of short-chain fatty acids, which have anti-inflammatory properties [10].
3. Immune modulation: Oral microbiota interacts with the immune system to promote tolerance and prevent excessive inflammatory responses.

Dysbiosis and disease

Dysbiosis refers to an imbalance in the microbial community that can lead to unfavourable health outcomes. Factors contributing to dysbiosis include antibiotic use, poor diet, smoking, and underlying health conditions [7].

Oral microbiota and oral diseases

Dental caries

Dental caries is a result of the accumulation of specific acidogenic bacteria, notably Streptococcus mutans, which ferment sugars and produce acids that demineralise tooth enamel [6]. The presence of certain bacteria associated with caries, such as Lactobacillus spp., indicates a shift from a healthy microbiota to a caries-prone microbiota.

Periodontitis

Periodontitis is a chronic inflammatory disease characterised by the destruction of the supporting structures of the teeth. It is associated with specific pathogenic bacteria, notably Porphyromonas gingivalis, which can invade host tissues and trigger inflammatory pathways [5]. The relationship between periodontitis and systemic diseases underscores the importance of oral health.

Oral microbiota and systemic diseases

Emerging evidence suggests that oral microbiota can influence systemic health and disease processes. Some notable examples include:

1. Cardiovascular disease: There is significant evidence linking periodontal disease with cardiovascular disease. Porphyromonas gingivalis and other periodontopathic bacteria have been detected in atherosclerotic plaques, suggesting a possible role in atherogenesis through inflammation and the infiltration of bacteria into the bloodstream [8].
2. Diabetes: Diabetes mellitus is associated with changes in the oral microbiota, and periodontal disease is often seen in patients with diabetes. The interplay between glucotoxicity and the oral microbiome can exacerbate periodontal inflammation, creating a cycle of worsening glycemic control [3].
3. Other diseases: Recent studies have also suggested associations between oral microbiota and diseases such as Alzheimer's disease, respiratory infections, and even certain cancers. The mechanisms are not fully understood but may involve systemic inflammation and dysregulated immune responses.

Comparative analysis of oral microbiota in health and disease

The comparative analysis of oral microbiota between health and disease states illustrates the profound impact of microbial communities on health outcomes. The following key differences have been observed:

1. Diversity: A healthy oral microbiota is generally more diverse than that found in diseased states. Reduced diversity often correlates with disease severity [1].
2. Pathogen prevalence: Specific pathogens are more prevalent in diseased states. The presence of these pathogens is often accompanied by a decrease in beneficial microorganisms.
3. Metabolic functions: Dysbiotic communities exhibit altered metabolic profiles, leading to the production of harmful metabolites that contribute to disease progression [4].

Disclaimer- The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of M3 India.

About the author of this article: Dr Partha Ghosh, BNYS, MD(YS), is a general physician and a medical writer from Siliguri, Darjeeling.