Oral Microbiome - Oral Diseases Axis

Two extremely common chronic diseases are dental caries (cavities) and periodontal disease (gum disease). Both of these conditions are considered multi-factorial. Yet, there are many common factors in their development. A central one is the microbial communities living in the mouth.
The total species of bacteria, viruses, fungi living together in a complex ecosystem is called the microbiota. Their genetic information is the microbiome.

Dental plaque is an example of a microbial biofilm with a diverse composition. It’s found naturally on teeth and advantageous to the host in certain compositions. The benefits include protection against pathogenic (potentially harmful) microorganisms and tooth wear. There are about 700-1000 species in the oral microbiota. In balance, these provides an optimal environment for health.
Negative shifts in the oral microbiome are called dysbiosis.

Dysbiosis potentially correlated with many diseases, such as cavities, periodontal disease, oral cancer, and some systemic diseases. I wrote more about it in a previous post.

Dental caries is the most common chronic disease in the oral cavity. Bacteria are the main pathogens, and symptoms include hard tissue destruction of the teeth.

Gum disease and at a later stage periodontal disease is a microbial infection resulting from the overgrowth of pathogenic species within the microbial community.

  plaque on teeth

Dental caries can be defined as a localized chemical loss of the tooth structure caused by the metabolic activity of dysbiotic dental biofilm that covers hard surfaces. This loss is reversible in its early stage. The final outcome of dental caries is determined by multiple factors such as saliva, exposure to fluoride, and sugar consumptions.

These influence the dynamic balance between the de- and remineralization processes, where building-block minerals can move in and out of the tooth structures.
The microbial factors are known as indispensable causes of the onset and progress of dental caries. The members of the oral microbiome in health or disease appear to select depending on the availability of nutrients.

A diet high in sugar and carbs paired with bad oral hygiene promotes changes in the healthy ecosystem where acid producing and acid preferring species e.g. Streptococcus mutans increase in biomass.
Periodontal disease:
Periodontal disease affects the soft tissues and the bone that support teeth. It was ranked the 31st among the leading causes of years lived with disability worldwide.
In periodontitis, imbalanced microbiota and keystone pathogens such as Porphyromonas gingivalis and Fusobacterium nucleatum appear in greater proportion than in health.
Disruptions in the healthy, natural balance make the microbiota less robust where opportunist pathogens can out-compete other species. The transition from periodontal health to disease is accompanied by a shift from a health-compatible microbiota to a pathogen-enriched community. This initiates and maintains the clinical signs of periodontal inflammation and destruction.

These microbes then can enter the circulation and linked to several systemic conditions.
Keeping the oral flora in a healthy balance is important to prevent oral and systemic conditions.

21st century daily habits are often working against us, but with good oral hygiene and diet practices, the natural desirable state can be maintained.
References, further readings:
https://pubmed.ncbi.nlm.nih.gov/10553246/ https://www.amhsr.org/articles/microbiology-of-dental-caries-a-literature-review-5239.html https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5940813/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4346134/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5141605/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278837/

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