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The Oral Microbiome is Critical in Understanding Health and Disease – Part 2

Dental care and the oral microbiome

Last week’s blog gave an overview of the oral microbiome. In part two, the focus is on dysbiosis and associated illness.

Poor oral hygiene, immunological disorders, and certain genetic predispositions are major factors that contribute to the initiation of the disease cycle.

These risk factors may cause microbes to either grow abnormally or acquire virulence factors, leading to dysbiosis and disease. The key to oral health is maintaining balance within the diverse microbes of the oral microbiome, which may interact both positively and negatively with the host. However, cause and effect relative to these ecological shifts in oral microbiome composition are still not entirely understood as of yet.(1)

Decay is a polymicrobial disease, influenced by many factors

In dental decay, carbohydrates are fermented to organic acids (shown in red below). These organic acids lower local pH, resulting in net demineralisation of the tooth surface and driving dysbiosis in which both acid-producing and acid-tolerating microbiota are present.

In contrast, in health, (shown in blue below) a more complex and balanced pattern of metabolism involves the catabolism of salivary proteins and glycoproteins, with the generation of alkali to neutralise any acid products.

Upon low salivary clearance, overly frequent snacking, smoking, and presence of other risk factors, demineralisation outweighs remineralisation and results in a net mineral loss, which eventually presents itself in the form of tooth decay.

Traditional caries-associated species include Streptococci mutans and Lactobacillus species. Increasing evidence now points to the roles of Actinomyces, Bifidobacterium, and other Gram-positive rod species play important roles in the community.(2)


Kilian et al. (adapted from de Soet, Zaura and Takahashi),
British Dental Journal, licensed under CC BY 4.0

Polymicrobial Synergy and Dsybiosis in Periodontitis

Recent advances in metagenomic, metatranscriptomic, and mechanistic studies suggest a new model of periodontal disease. In this model, disease results from polymicrobial synergy and dysbiosis, which perturbs the balance from homeostasis to disease in oral and extraoral sites.(3)

Recent research suggests that Potassium may be a key signal in host-microbiome dysbiosis in periodontitis, and may also point to the role of changing diet to prevent periodontal disease progression.(4)

Autoimmune Disease and the Oral Microbiome

New published data indicates that changes in the symbiotic and dysbiotic interactions of the core and variable microbiome are associated with a number of autoimmune diseases, as shown below.

Changes in the oral microbiome due to the host’s environment, genetic susceptibility, diet, and smoking may contribute to the pathogenesis of Sjogren’s syndrome, rheumatoid arthritis, systemic lupus, erythematosus, and Crohn’s disease. There is a delicate balance between the immune system and the composition of microbiota leading to dysbiosis, or microbial imbalance, and autoimmune progression.(5)

Bonnie Feldman


Bonnie Feldman is the Digital Health Analyst and Chief Growth Officer at DrBonnie360 – Your Autoimmunity Connection.

If you enjoyed this, you may also like ‘Streptococcus salivarius K12 BLIS in the treatment of oral cavities and otitis media’.

  1. Zarco, Vess et al. “The Oral Microbiome in Health and Disease and the Potential Impact on Personalized Dental Medicine.” Oral Diseases 18.2 (2012): 109–120.
  2. Dewhirst, Floyd E. “The Oral Microbiome: Critical for Understanding Oral Health and Disease.” Journal of the California Dental Association 44.7 (2016): 409–10.
  3. Hajishengallis, George. “Periodontitis: from microbial immune subversion to systemic inflammation,” Nature Reviews Immunology (2015): 30–44.
  4. Yost, Susan et al. “Potassium is a key signal in host-microbiome dysbiosis in periodontitis,” PLOS Pathogens (2017): e1006457.
  5. Nikitakis, N. G., et al. “The autoimmunity–oral microbiome connection.” Oral diseases (2016).

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