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The Oral Microbiome is Critical in Understanding Health and Disease

New understanding of the microbiome is changing ideas about health and is pertinent to our thinking about the role of the oral microbiome in systemic disease. This article gives an overview of the oral microbiome, while next week’s will focus on dysbiosis and associated illness.

Contrary to what I was taught as a dentist training in the 1980s, the goal of good oral hygiene is not simply aimed towards killing the “bad” bacteria, but more reflective of balancing the ecology of the oral microbiome. On a recent trip to NYC I met with Dr. Gerry Curatola, who seems to agree with this in his recent book, The Mouth-Body Connection.(1)

Dr. Curatola explains, “Not only do we know that human health depends on maintaining a balanced relationship with and within complex communities of microorganisms, but microbes are recognised to contribute to disease in previously unexpected ways… overzealous oral hygiene is being recognised as a cause of disease.” (Curatola, 2017).

The mouth as a gateway

While the mouth is one of the body parts most vital to our health, its significance is often overlooked. In fact, even as I delved into my research on the oral microbiome I was surprised by numerous facts about oral health, despite my background as a clinical dentist.

I was startled to find that nearly half of American adults have periodontitis, the most severe form of gum disease, with gum disease increasing one’s likelihood of meeting ADA guidelines for diabetes screening by an average of 30%.(2) Additional statistics are cited below.


What is the oral microbiome?

Over the past 15 years, microbiologists contributing to the Human Oral Microbiome Database (HOMD) have cultured 68% of an estimated 700 different species of oral bacteria.

The microbiome is highly variable both between and within individuals. Various sectors of an individual’s microbiome show great diversity between compartments in the body; species of bacteria present differ by location (e.g., hair, skin, stomach, and oral cavity, as shown below).

In contrast to the GI tract, in which high level of species diversity is correlated with better health, oral disease is actually associated with an increased diversity and richness of the oral microbiome. The oral cavity, as shown below, varies in species diversity, with additional influence from biofilms and environmental conditions that may hinder or enhance disease.


Belizário and Napolitano, Frontiers in Microbiology, licensed under CC BY 4.0

Why should we care?

New understanding of the oral microbiome is shaping how we think about caries, periodontal and systemic diseases. While the traditional view held that these diseases may be caused by a limited number of causal pathogens, we now think of the oral microbiome as a finely tuned community that determines the balance not only between oral health and disease, but also some systemic diseases.(3)

What happens when the oral microbiome is out of balance?

The mouth is positioned as the initial meeting place between the immune system, the gut, the outside environment, microbes, pathogens, toxins and food nutrients. As this first point of contact, the oral microbiome seeds the rest of the GI tract, with a 45% overlap between the microbes found in the mouth and in the colon.

The oral microbial ecosystem is vital to maintaining oral and systemic health. Salivary flow and biofilms on the teeth and soft tissue maintain microbial equilibrium within the oral cavity and protect against manifestation of pathogens. In contrast, disturbing homeostasis of the oral cavity can stir pathogen activity and lead to oral disease.

A healthy oral microbiome can only be maintained with good oral hygiene and a well functioning immune system.

Bonnie Feldman


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

Read part 2.

  1. Curatola, Gerald P. et al., “The Mouth-Body Connection: a 28-Day Program to Create a Healthy Mouth, Reduce Inflammation, and Prevent Disease throughout the Body,” Center Street, (2017).
  2. Strauss, S. M., et al., “The dental office visit as a potential opportunity for diabetes screening: an analysis using NHANES 2003-2004 data.” Journal of Public Health Dentistry (2010): 70: 156–162.
  3. Zhang, Xuan et al. “The Oral and Gut Microbiomes Are Perturbed in Rheumatoid Arthritis and Partly Normalized after Treatment.” Nature Medicine 21.8 (2015): 895–905.

2 Responses to “The Oral Microbiome is Critical in Understanding Health and Disease”

  1. What about oral dysbiosis that involves volatile sulfur compounds and halitosis? What theoretical ways are available to control oral bacteria that are not necessarily infections or infectious, but merely imbalanced?

    Research and organizations regarding this subject would be very helpful.

    Thank you.


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