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Oral Microbiome

The role of the oral microbiome on our health and function. And the impact of the gut microbiome and immune system on our oral microbiome.

Oral cancer |


Review, 2018: Cariogenic microbiome and microbiota of the early primary dentition: a contemporary overview "The review illustrates the immense complexity and the diversity of the human oral-microbiota of the cariogenic plaque microbiome in early childhood caries (ECC), and the daunting prospect of its demystification."

Review, 2017: Prebiotic compounds in food impact the oral microbiome: The role of wine and food polyphenols in oral health.

Severe form of inflammatory bowel disease linked to a strain of mouth bacteria (Campylobacter concisus) (Oct 2020) Analysis of complete Campylobacter concisus genomes identifies genomospecies features, secretion systems and novel plasmids and their association with severe ulcerative colitis.

A Common Gum Infection Bacteria (P. gingivalis) May Also be Causing Alzheimer’s. Porphyromonas gingivalis in Alzheimer’s disease brains: Evidence for disease causation and treatment with small-molecule inhibitors (Jan 2019)

Oral bacteria accelerate pancreatic cancer development in mice (Jan 2024, P. gingivalis) "our findings demonstrate a causal role for P. gingivalis in pancreatic cancer development in mice"

Poor oral health linked to a 75% increase in liver cancer risk. The association between self-reported poor oral health and gastrointestinal cancer risk in the UK Biobank: A large prospective cohort study (June 2019)

Klebsiella and Providencia emerge as lone survivors following long-term starvation of oral microbiota (Apr 2019) "Klebsiella spp. are significant human pathogens. The ability of Klebsiella to outcompete its neighbors during starvation and survive long-term in saliva is particularly noteworthy"

Periodontal disease bacteria may kick-start Alzheimer's. Chronic oral application of a periodontal pathogen results in brain inflammation, neurodegeneration and amyloid beta production in wild type mice (2018)

Dysbiosis of oral microbiota and its association with salivary immunological biomarkers in autoimmune liver disease (2018): - Dysbiosis of the oral microbiota is associated with inflammatory responses and reflects changes in the gut microbiota of patients with AILD (auto immune liver disease).

Does the oral microbiome colonize the gut?

Mixed evidence.

Oral bacteria relative abundance in faeces increases due to gut microbiota depletion and is linked with patient outcomes (May 2024)

No evidence for colonization of oral bacteria in the distal gut in healthy adults (Sep 2021)

Extensive Transmission of Microbes along the Gastrointestinal Tract (2018) "we found that transmission to, and subsequent colonization of, the large intestine by oral microbes is common and extensive among healthy individuals. This establishes the oral cavity as an endogenous reservoir for gut microbial strains, and oral-fecal transmission as an important process that shapes the gastrointestinal microbiome in health and disease"

Impact of gut microbiome on the oral microbiome:

"Our current theory is that your gut bacteria determine whether your oral bacteria cause cancer" (2017): - this is inline with my own understanding from following the literature.

"Evidence found of oral bacteria contributing to bowel disorders" - but it sounds like it's dysbiosis of the gut allowing oral bacteria to proliferate in the gut and cause problems (2017) Ectopic colonization of oral bacteria in the intestine drives TH1 cell induction and inflammation.

The stress hormone cortisol induces virulence in the oral microbiome (2018) - The effect of the stress hormone cortisol on the metatranscriptome of the oral microbiome
The gut microbiome regulates hormones:

Impact of oral microbiome on the gut microbiome:

Oral Porphyromonas gingivalis infection affects intestinal microbiota and promotes atherosclerosis (2023, mice)

Effect of Porphyromonas gingivalis infection on gut dysbiosis and resultant arthritis exacerbation in mouse model (Oct 2020) "Pg oral infection affected gut microbiota dysbiosis and joint destruction via increased CP generation."

Virginia Tech researchers discover that mouth bacterium may cause colon cancer to spread (Jul 2020, in vitro) "our findings show that F. nucleatum both directly and indirectly modulates immune and cancer cell signaling and migration" Fusobacterium nucleatum host-cell binding and invasion induces IL-8 and CXCL1 secretion that drives colorectal cancer cell migration.

Oral Administration of Porphyromonas gingivalis Alters the Gut Microbiome and Serum Metabolome (2018)

Periodontal pathogenic bacteria, Aggregatibacter actinomycetemcomitans affect non-alcoholic fatty liver disease by altering gut microbiota and glucose metabolism (2017, mice)

How to improve the oral microbiome?

Review, 2018: Periodontitis and the microbiome: a systematic review and meta-analysis "It seems that changes in the taxonomic composition of the microbiome rather than single targeted pathogens is the key determinant of periodontitis"

Antimicrobial peptide GH12 prevents dental caries by regulating dental plaque microbiota (May 2020, n=5)

Tongue cleaning more effective than mouthwash: Frequency of Tongue Cleaning Impacts the Human Tongue Microbiome Composition and Enterosalivary Circulation of Nitrate (Mar 2019) "results further support the concept of a symbiotic oral microbiome contributing to human health via the enterosalivary nitrate-nitrite-NO pathway"

Blood pressure-lowering effect of exercise is significantly reduced when people rinse their mouths with antibacterial mouthwash. (Jul 2019, 23 healthy adults) Post-exercise hypotension and skeletal muscle oxygenation is regulated by nitrate-reducing activity of oral bacteria.

The Oral Microbiota Is Modified by Systemic Diseases (Oct 2018) Successful RA treatment with anti-inflammatory drugs partially reverses the oral microbial dysbiosis. Systemic diseases characterized by enhanced inflammation disturb the oral microbiota & point to IL-17 as key mediator in this process

Effect of 12-month weekly professional oral hygiene care on the composition of the oral flora in dentate, dependent elderly residents: A prospective study. (2016) "Assisted oral hygiene care alone is not sufficient to regain an oral microbial flora associated with good oral health"

Evaluation of the Oral Microbiome before and after Treatments for Halitosis with Photodynamic Therapy and Probiotics—Pilot Study (May 2024) "Treatment with aPDT (Antimicrobial Photodynamic Therapy) or probiotics was not able to change the bacteria present in the biofilm of the tongue"

Dysbiosis of oral microbiome persists after dental treatment-induced remission of periodontal disease and dental caries (Sep 2023, n=62)

Oral Microbiota Transplant:

Safety, Feasibility, and Advantages of Oral Microbiota Transplantation: The First Clinical Case (Jun 2024) "Oral microbiota transplantation was shown to effectively prevent the development of oral mucositis after chemotherapy"