The Microbiome of the Mouth

Written by Ethan Prabhu

Bacteria’s role in the mouth is much bigger than you can imagine. It plays a role in many aspects, including teeth and gum health, the smell of your breath, and oral diseases. But how do bacteria impact our mouth in so many different ways?

Plaque is one of the biggest examples of bacteria’s effect on the mouth, as bacteria are actually a direct cause of it. Plaque is formed when food particles are broken down by bacteria on teeth to form a film known as dental plaque. The bacteria actually feed on sugars and starches found in foods like milk, candy, or pasta. (Cleveland Clinic, 2023). Although plaque can be cleaned by normal dental hygiene, it can cause problems if left untreated. Dental calculus or tartar is hardened plaque, and it can only be cleaned by a dental professional. Plaque can cause a multitude of problems, like halitosis (chronic bad breath) and gingivitis (irritation of the gums). (Abebe, 2021)

But what is the actual microbial aspect of plaque, and what is the specific pathway of bacteria forming plaque? Right after you brush, your saliva forms a layer of proteins on the teeth, known as acquired pellicle formation. (Chawhuaveang et al., 2021). This provides a perfect home for bacteria to stick to. Bacteria then colonize the teeth, binding to the protein layer, and start to digest sugars and starches. These bacteria then form a biofilm, which is a structure of bacteria covered in a slimy, protective layer that provides protection for your teeth against treatments. (Saini et. al., 2011). It’s almost like an apartment complex on your teeth! These bacteria continue to proliferate, eventually leading to the production of acids from food particulates, causing tooth decay. Many different bacteria partake in the biofilm. An example is Streptococcus, which acts as an early colonizer of the teeth. Other bacteria that colonize the mouth include P. gingivalis and Lactobacillus (Lu et al., 2019)

This plaque can then cause oral health issues. One of the exemplars of this is Gingivitis. As bacteria in plaque continue to sit on the teeth, they release toxins. These toxins cause a response in the gums, leading to the typical symptoms of Gingivitis, like gum recession, puffiness, redness, and overall irritation. As plaque hardens into dental calculus, it creates a permanent cycle of irritation, causing problems for people (Mayo Clinic Staff, 2023). Gingivitis can then progress into Periodontitis, which is especially severe and can cause permanent bone deterioration.

Overall, bacteria in the mouth are truly the main determiner of every oral issue you face. Regular cleanings with the dentist keep these bacteria at bay and preserve your oral health. However, societal issues like poverty can cause regular dental cleanings to be missed, so daily at-home oral hygiene becomes more important than ever. It’s important to know how things like bacteria can affect our oral health to help preserve our teeth for our full lifetime!

Works Cited

1. Chawhuaveang, D. D. (2021). Acquired salivary pellicle and oral diseases: A literature review. Journal of Dental Sciences, 16(1), 523–529. https://doi.org/10.1016/j.jds.2020.10.007
2. Cleveland Clinic. (2020, October 14). Dental Plaque: What Is It, Causes, How to Remove, Prevent & Treat. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/10953-plaque
3. Facts About Gingivitis: Symptoms, Prevention and Treatment. (2026). Baystate Dental. https://baystate-dental.com/blog/gingivitis-symptoms-and-causes-in-western-massachusetts
4. Gedif Meseret, A. (2021). Oral Biofilm and Its Impact on Oral Health, Psychological and Social Interaction. International Journal of Oral and Dental Health, 7(1). https://doi.org/10.23937/2469-5734/1510127
5. Huang, R., Li, M., & Gregory, R. L. (2011). Bacterial interactions in dental biofilm. Virulence, 2(5), 435–444. https://doi.org/10.4161/viru.2.5.16140
6. Lu, M., Xuan, S., & Wang, Z. (2019). Oral microbiota: A new view of body health. Food Science and Human Wellness, 8(1), 8–15. https://doi.org/10.1016/j.fshw.2018.12.001
7. Mayo Clinic. (2023, November 16). Gingivitis — symptoms and causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/gingivitis/symptoms-causes/syc-20354453
8. Saini, R., Saini, S., & Sharma, S. (2011). Biofilm: A dental microbial infection. Journal of Natural Science, Biology, and Medicine, 2(1), 71–75. https://doi.org/10.4103/0976-9668.82317