References

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Suggested reading to learn more about the oral-systemic link

Alzheimer’s Disease

“Together these results suggest a potential link with AD via the periodontal pathogen translocating from its original oral niche to the brain. ApoEnull mice induced with periodontal disease demonstrated the intracerebaral  [sic] innate immune responses were initiated by local CNS cells, which not only contributed to a higher inflammatory burden but also bystander damage of functional neurons in the hippocampus area of the brain which is associated with memory. […] Early treatment of periodontal disease in addition to greater awareness of the importance of maintaining good oral health may halt or slow down the progression of this debilitating disease.”
Poole, Sophie. Aetiological links between oral pathogens and dementia. 2014.

Autoimmune disorders and immune system

“The oral, gut, and skin microbiotas could play a key role in the pathogenesis of systemic and organ-specific autoimmune diseases. […] Moreover, changes in the oral microbiota are found to be associated with several other diseases including squamous cell carcinoma, atherosclerosis, bacteraemia, and rheumatoid arthritis.”
Øyvind Bruserud, et al. Oral microbiota in autoimmune polyendocrine syndrome type 1. J Oral Microbiol. 2018; 10(1): 1442986.

“More and more new data indicate that changes in the oral microbiome may not only affect the presence and severity of oral lesions but also the underlying imbalances in pathogenesis of systemic diseases, including autoimmune RA, SS, CD, and SLE. Factors that affect the balance between the immune system and composition of microbiota lead to dysbiosis and may lead to loss of tolerance and subsequent autoimmune disease.”
NG Nikitakis, W Papaioannou, LI Sakkas, E Kousvelari. The autoimmunity – oral microbiome connection. Oral Diseases (2017) 23, 828–839

“Several host-adapted pathogens and commensals have evolved mechanisms to evade the host innate immune system inducing a state of low-grade inflammation. Epidemiological studies have also documented the association of a subset of these microorganisms with chronic inflammatory disorders.”
Carolyn D. Kramer and Caroline Attardo Genco. Microbiota, Immune Subversion, and Chronic Inflammation. Front Immunol. 2017; 8: 255.

Cancer

“Fusobacterium nucleatum might be the cause or consequence of disease in many tissues in and outside the mouth.” Chamutal Gur, et al. An Oral Commensal Associates with Disease: Chicken, Egg, or Red Herring? Immunity, Volume 42, Issue 2, 17 February 2015, Pages 344-355.

Cardiovascular disease

Rajiv Saini, et al. Periodontal disease linked to cardiovascular disease. Journal of Cardiovascular Disease Research Vol. 1 / No 3

“Treponema denticola is a predominantly subgingival oral spirochete closely associated with periodontal disease and has been detected in atherosclerosis. […] Our results in the current study agree with previous studies by other groups studying Chlamydia pneumoniae (32) and P. gingivalis (5), which have highlighted a synergistic association between infection and hyperlipidemia, culminating in the development of atherosclerosis in mice. […] Using a combinatorial approach consisting of a natural course of infection and a long-term duration of infection within an effective mouse model for evaluating accelerated atherosclerosis, we demonstrate that chronic oral infection with T. denticola can initiate and accelerate atherosclerotic plaque progression.”
Sasanka S. Chukkapalli, et al. Invasion of Oral and Aortic Tissues by Oral Spirochete Treponema denticola in ApoE−/− Mice Causally Links Periodontal Disease and Atherosclerosis. Infect. Immun. May 2014 vol. 82 no. 5 1959-1967.

Gastrointestinal disorders

“The anaerobic, Gram-negative bacterial species Fusobacterium nucleatum is a common resident of the human mouth and gut and varies in its pathogenic potential. In this study, we demonstrate that highly invasive F. nucleatum isolates derived from the inflamed guts of Crohn’s disease patients evoked significantly greater MUC2 and tumor necrosis factor alpha (TNF-α) gene expression than minimally invasive strains isolated from the noninflamed gut in human colonic epithelial cells and in a rat ligated colonic loop model of infection.”
Poonam Dharmani, et al. Fusobacterium nucleatum Infection of Colonic Cells Stimulates MUC2 Mucin and Tumor Necrosis Factor Alpha. Infect Immun. 2011 Jul; 79(7): 2597–2607.

General

“Human oral cavity harbors the second most abundant microbiota after the gastrointestinal tract.”
Digvijay Verma, et al. Insights into the human oral microbiome Archives of Microbiology. May 2018, Volume 200, Issue 4, pp 525–540

“Now a recent paper makes a stronger case that a specific cell shape can be vital for the ability of a bacterium to cause disease.”
Kevin D. Young, 2010. The Twist in the Story.

“Yet, DNA-based identification methods such as polymerase chain reaction (PCR) suffer from high false-positive readings by the detection of DNA from dead bacterial cells.”
Dr. Andre Mickel, DDS MSD. Case Western Study Guide. 2016.

“The second ‘red-complex’ pathogen, T. denticola, belongs into the phylum Spirochaetes (Dashper et al., 2011), and can become extremely abundant in periodontitis (up to 50% of the polymicrobial plaque) while it is almost absent in health (Kilian et al., 2016).”
Zeng Z-L, Sztajer H, Jarek M, Bhuju S and Wagner-Döbler I (2018). Worlds Apart – Transcriptome Profiles of Key Oral Microbes in the Periodontal Pocket Compared to Single Laboratory Culture Reflect Synergistic Interactions. Front. Microbiol. 9:124

“The results of our previous interdisciplinary studies revealed species differences in oral microbial communities in patients with masticatory system disorders and with certain systemic diseases. In these, the immunological condition of the patients and the therapeutic procedures had different degrees of influence on the changes in oral microbiota.”
Paweł J. Zawadzki, t al. Examination of Oral Microbiota Diversity in Adults and Older Adults as an Approach to Prevent Spread of Risk Factors for Human Infections. BioMed Research International Volume 2017, Article ID 8106491.

Oral microbiota of periodontal health and disease and their changes after nonsurgical periodontal therapy. Casey Chen, et al. The ISME Journal volume 12, pages 1210–1224 (2018).