Insights Into the Oral Microbiome

When you think about oral health, regular brushing or reducing your sweets may be front of mind. But there’s another factor that is critical when it comes to oral health: the oral microbiome. Inside each of our mouths is a diverse community of bacteria, viruses, fungi and other microbes that, together with the genes they encode, make up the oral microbiome. The more we learn about this bustling ecosystem, the clearer it becomes that it plays a vital role in our overall health.

What is the oral microbiome, and what does it do?

Nearly every surface of the human body is covered in microbes, but your mouth is one of the most densely populated sites (second only to the human gut). Millions of microbial cells live on your teeth, gums, tongue, and other surfaces in your mouth, and they interact with each other and your own cells to help keep you healthy. Scientists have identified nearly 800 different species of bacteria that are found in the human oral microbiome¹, but each individual will host a microbial community that is unique to them.  Some of the most common members of the oral microbiome are species of Streptococcus, including Streptococcus mitis, S. sanguinis, S. gordonii, and S. salivarius.

One of the primary jobs of the oral microbiome is to support a healthy barrier that prevents pathogens and other potentially harmful substances from entering your body. Beneficial bacteria occupy spaces on oral surfaces, helping prevent harmful pathogens from making themselves at home. Additionally, members of a healthy oral microbiome work alongside the immune system to stimulate the production of antimicrobial peptides in saliva and to promote the tolerance of beneficial microbes, which prevents unnecessary inflammation^2,3. As the first point of contact between what goes in your body and the outside world, oral microbes play a critical role in protecting the oral cavity from infections and regulating inflammation, supporting both oral and overall health.

The microbiome and oral health

The oral microenvironment consists of a delicate balance between beneficial microbes and those that are potentially harmful but are generally found in low numbers in healthy individuals. However, when this balance is disrupted (known as dysbiosis) and harmful bacteria become dominant, it can lead to several oral health problems, including:

• Tooth decay: Tooth decay (also called dental caries) occurs when bacteria in the oral cavity produce acids that break down tooth enamel⁴. Certain bacteria thrive on sugars from food and beverages, producing acid as a byproduct of their metabolism. This acid gradually wears away the enamel and can eventually lead to cavities. mutans is one of the key contributors to tooth decay given its high acid-producing capabilities.
• Gum disease: Gingivitis is a common, mild form of gum inflammation caused by the build-up of plaque; a thin film made up mostly of bacteria that can be found on tooth surfaces. The acid and other waste products bacteria produce when they break down sugars can cause the gums to become red, swollen and sometimes painful. While some gingivitis is considered normal, failure to remove the plaque can lead to periodontitis, a chronic inflammatory disease that damages the gum tissue². This can cause gums to pull away from teeth, creating pockets where more bacteria can thrive and potentially leading to tooth loss.
• Bad breath: Also known as halitosis, bad breath is often caused by the overgrowth of certain types of bacteria that produce sulphur compounds, which are responsible for the unpleasant smell. In most cases, halitosis can be prevented or treated with good oral hygiene practices.

Systemic effects: how your oral microbiome influences your overall health

It makes sense that the overgrowth of harmful bacteria can wreak havoc on your oral health, but increasing research is revealing that the oral microbiome can influence your entire body. While we still don’t know all the ways that oral microbes influence different diseases, it is thought that the migration of infectious microbes to distant organs or tissues in the body, either through the digestive tract or the blood, can disrupt the local microbiome and promote inflammation. Alterations in the oral microbiome have now been observed in patients with inflammatory conditions such as inflammatory bowel disease⁵, certain types of cancer⁶, metabolic diseases^7,8 and Alzheimer’s disease⁹, among others. However, more research is needed for us to better understand how oral microbes interact with an individual’s genetics, immune system and lifestyle habits to influence these and other diseases.

Maintaining a healthy oral microbiome

There are several things you can do to promote a balanced oral microbiome. Try to maintain a healthy diet low in sugary foods and beverages, which can promote the growth of bacteria associated with tooth decay. Avoid smoking, as this is known to disrupt the oral microbiome and increase the risk of oral diseases. Finally, practice good dental hygiene by brushing and flossing daily to remove the plague and having regular dental visits.

The take-away

The importance of the oral microbiome extends beyond maintaining oral health. By understanding and caring for your oral microbiome, you can promote the health of your whole body.

 

References

1. Dewhirst, F. E. et al. The human oral microbiome. J Bacteriol 192, 5002-5017, doi:10.1128/jb.00542-10 (2010).
2. Lamont, R. J., Koo, H. & Hajishengallis, G. The oral microbiota: dynamic communities and host interactions. Nat Rev Microbiol 16, 745-759, doi:10.1038/s41579-018-0089-x (2018).
3. Liu, Y. et al. The interplay between oral microbes and immune responses. Frontiers in Microbiology 13, doi:10.3389/fmicb.2022.1009018 (2022).
4. Spatafora, G., Li, Y., He, X., Cowan, A. & Tanner, A. C. R. The Evolving Microbiome of Dental Caries. Microorganisms 12, doi:10.3390/microorganisms12010121 (2024).
5. Read, E., Curtis, M. A. & Neves, J. F. The role of oral bacteria in inflammatory bowel disease. Nat Rev Gastroenterol Hepatol 18, 731-742, doi:10.1038/s41575-021-00488-4 (2021).
6. Tuominen, H. & Rautava, J. Oral Microbiota and Cancer Development. Pathobiology 88, 116-126, doi:10.1159/000510979 (2021).
7. Li, Y. et al. Oral, Tongue-Coating Microbiota, and Metabolic Disorders: A Novel Area of Interactive Research. Front Cardiovasc Med 8, 730203, doi:10.3389/fcvm.2021.730203 (2021).
8. Matsha, T. E. et al. Oral Microbiome Signatures in Diabetes Mellitus and Periodontal Disease. J Dent Res 99, 658-665, doi:10.1177/0022034520913818 (2020).
9. Wan, J. & Fan, H. Oral Microbiome and Alzheimer’s Disease. Microorganisms 11, doi:10.3390/microorganisms11102550 (2023).

 

The information on this website is not intended to diagnose, treat, or prevent any medical condition. See a full disclaimer here.