The educational content in this post, elaborated in collaboration with Bromatech, was independently developed and approved by the GMFH publishing team and editorial board.
Why oral microbiome matters?
When we think about the vast community of bacteria living in our mouths, it’s fascinating to realize that at least 1,000 different species, organized into nine groups, have been identified. Most of these bacteria are harmless and do not typically cause diseases in healthy individuals, but can cause problems in circumstances like illness, medical treatments like chemotherapy, and when the body’s immune system is compromised (what we know as pathobionts)1.
In healthy conditions, the strict pathogen species have the least representation in the mouth and are often under the control of the entire bacterial community. In fact, under normal health conditions, oral microbes and the host’s cells communicate in different ways and are in perfect dynamic balance, creating an environment that supports overall health.
Several studies have shown that a balanced oral microbiota helps prevent inflammation not just in the mouth, but in other parts of the body, like the lungs and the intestines. For instance, changes to the oral microbiota, such as those occurring during gum disease, have been recently linked to inflammatory conditions, such as inflammatory bowel disease and bowel cancer.
What happens in your oral microbiome does not stay in your oral microbiome
Teeth, saliva, buccal mucosa, soft and hard palate, gingival sulcus, tonsils, throat, and lips are among the microbial habitats found in the oral cavity. However, the majority of these bacteria live on the tongue, especially the back part. This is an important spot in relation to oral health because it can e.g. also harbor the periodontal pathogen bacteria that cause gum disease.
This anatomical site has unique physical-chemical conditions that modulate the bacterial composition; for example, this area shows the lowest amount of oxygen, which is similar to the colorectal tract. Saliva carries food nutrients to nourish these bacteria and helps maintain stable levels of bacteria involved in health. Several studies suggest that oral dysbiosis may mostly come from the assemblage of associated microbial cells (biofilm) on the dorsum of the tongue, where the number of potential pathogens often exceeds the physiological limit because of the host’s bad eating habits. Clinical observational studies have also shown that the coating on the tongue is related to dysbiosis status. In fact, changes in the coating are directly linked to changes in the structure and composition of the bacterial biofilm. This coating can vary in appearance and thickness and serves as a good indicator of oral and overall health2.
And how can oral dysbiosis be detected in practice? A breath test for bacterial products, such as volatile sulfur compounds (VSC), especially hydrogen sulfide and methyl sulfide, is commonly used for diagnosing bad breath and oral dysbiosis in a lab3. This test complements studies that examine the tongue coating.
When there is dysbiosis, the oral microbiome produces more compounds, such as proteases and molecules like endotoxin and leukotoxins, which can alter the immune system and inflammatory response4. At the same time, saliva from the tongue releases different bacteria that spread to other parts of the mouth, such as the periodontal area, or other organs. Thus, maintaining a balance between the beneficial and harmful effects of these bacteria is crucial for oral and overall health.
Oral bacteria travel to other body sites through these ways
Oral pathogens and commensal bacteria can move to other parts of the body in several ways, with the oral-gut axis being the most common5. The oral microbiome and the gut microbiome are interconnected, and this connection is crucial for understanding how oral health impacts overall health. The gut may also facilitate the spread of oral pathogens throughout the body. Another pathway is the transient presence of bacteria in your blood (bacteremia)6, which is a silent process where oral bacteria temporarily enter the bloodstream. This can occur after certain dental hygiene activities or medical procedures that disturb the oral mucosa, allowing bacteria or their toxins to enter the bloodstream.
The mouth serves as the origin of bacteria associated with numerous systemic diseases. Among these pathogens are Porphyromonas gingivalis, Fusobacterium nucleatum, and other oral periodontal pathogens. These bacteria can migrate from the tongue to the saliva and bloodstream through inflamed oral tissues, thereby exacerbating the onset of various degenerative conditions such as chronic periodontitis, atherosclerosis, heart disease, rheumatoid arthritis, Alzheimer’s disease, and colorectal cancer7,8.
How to balance your oral microbiome?
Science-informed ways to prevent and manage oral dysbiosis include9,10:
- Maintaining good oral hygiene practices: Regular brushing, flossing, monitoring the tongue’s coating, and dental check-ups are essential. Professional dental cleanings and treatments for periodontal disease are also crucial in managing oral and systemic health.
- Lifestyle changes: quitting smoking, managing stress, and following a healthy diet can help maintain a balanced oral microbiome.
- Probiotics: In cases of dysbiosis signals, such as halitosis, specific oral probiotics might provide some benefits alongside tongue brushing. For instance, some probiotics might help prevent halitosis, maintain a healthy balance of the oral microbiome, and keep at bay dangerous bacteria involved in gum disease.
Overall, the connection between oral bacteria and systemic diseases underscores the importance of comprehensive oral care as part of overall health management. By addressing oral diseases and maintaining good oral hygiene practices, individuals can potentially reduce their risk of developing various systemic degenerative conditions11.
References
1) Li X, Liu Y, Yang X, Li C, Song Z. The Oral Microbiota: Community Composition, Influencing Factors, Pathogenesis, and Interventions. Front Microbiol. 2022; 13: 895537. doi: 10.3389/fmicb.2022.895537.
2) Xiao P, Hua Z, Kang X, Lu B, Li M, Wu J, Dong W, Zhang J, Cheng C. Influence of Oral Intaking Habit on Tongue Coating Microbiota in Patients with Esophageal Precancerous Lesions. J Cancer. 2022; 13(4): 1168-1180. doi: 10.7150/jca.67068.
3) Li Z, Li J, Fu R, Liu J, Wen X, Zhang L. Halitosis: etiology, prevention, and the role of microbiota. Clin Oral Investig. 2023; 27(11): 6383-6393. doi: 10.1007/s00784-023-05292-9.
4) Chimenos-Kustner E, Giovannoni ML, Schemel-Suarez M. Dysbiosis as a determinant factor of systemic and oral pathology: importance of microbiome. Med Clin (Barc). 2017; 149(7): 305-309. doi: 10.1016/j.medcli.2017.05.036.
5) Abdelbary MMH, Hatting M, Bott A, Dahlhausen A, Keller D, Trautwein C, Conrads G. The oral-gut axis: Salivary and fecal microbiome dysbiosis in patients with inflammatory bowel disease. Front Cell Infect Microbiol. 2022; 12: 1010853. doi: 10.3389/fcimb.2022.1010853.
6) Dubey R, Jalili VP, Jain S, Dubey A. Transient bacteremia consequent to tooth brushing in orthodontic patients. Prog Orthod. 2012; 13(3): 237-245. doi: 10.1016/j.pio.2012.02.004.
7) Asili P, Mirahmad M, Rezaei P, Mahdavi M, Larijani B, Tavangar SM. The Association of Oral Microbiome Dysbiosis with Gastrointestinal Cancers and Its Diagnostic Efficacy. J Gastrointest Cancer. 2023; 54(4): 1082-1101. doi: 10.1007/s12029-022-00901-4.
8) Thomas C, Minty M, Vinel A, Canceill T, Loubieres P, Burcelin R, Kaddech M, Blasco-Baque V, Laurencin-Dalicieux S. Oral Microbiota: A Major Player in the Diagnosis of Systemic Diseases. Diagnostics (Basel). 2021; 11(8):1376. doi: 10.3390/diagnostics11081376.
9) Cugini C, Ramasubbu N, Tsiagbe VK, Fine DH. Dysbiosis From a Microbial and Host Perspective Relative to Oral Health and Disease. Front Microbiol. 2021; 12: 617485. doi: 10.3389/fmicb.2021.617485.
10) National Institute of Dental and Craniofacial Research. Oral hygiene. October 2023. Available: https://www.nidcr.nih.gov/health-info/oral-hygiene (accessed on 28th May 2024)
11) Inchingolo F, Inchingolo AM, Malcangi G, et al. The benefits of probiotics on oral health: systematic review of the literature. Pharmaceuticals. 2023; 16(9):1313. doi: 10.10.3390/ph16091313.