Periodontitis
The oral microbiome is complex, and shifts in
the abundances of several types of bacteria can lead to periodontitis (Di Stefano et al., 2022). Even in low abundances, P. gingivalis
can influence the composition of the rest of the microbiome in ways that lead to inflammation and periodontal bone loss by exploiting the host immune system (Hajishengallis et al., 2011)
Mucositis/Peri-implantitis
Peri-implant mucositis, and later, peri-implantitis, can develop when a biofilm forms around the implant. Disease progression corresponds with an increased diversity of the submucosal bacterial community and higher relative abundances of several pathogenic or pathogen-associated populations (Belibasakis and Manoil, 2021; Butera et al., 2022). Fortunately, mucositis and peri-implantitis plaque microbiomes can revert to healthy baselines with antibiotic and/or mechanical intervention (Bazzani et al., 2024).
Adverse pregnancy outcomes
Pregnancy is associated with decreased markers of periodontal health and changes in the oral microbiome. Associations have been made between maternal periodontitis and preterm birth, low birth weight, and preeclampsia (Ye and Kapila, 2021) (and sources within).
Diabetes
Diabetes exacerbates the likelihood and severity of periodontal disease (Graves et al., 2020), although this bidirectional relationship may also be affected by periodontal pathogens triggering the host immune system to activate proinflammatory responses (Tang et al., 2022).
Rheumatoid Arthritis
Several studies have associated rheumatoid arthritis and periodontitis (Li et al., 2017), and P. gingivalis has been shown to produce specific peptides that trigger the host immune response in rheumatoid arthritis (Hitchon et al., 2010).
Colon Cancer
Studies investigating relationships between oral microbiota and cancer are predominantly correlative. Fusobacterium nucleatum has been associated with the progression of colorectal cancer, although somewhat inconsistently. P. gingivalis and Aggregatibacter actinomycetemcomitans are suggested to activate immune pathways that play roles in the development of pancreatic cancer, and P. gingivalis and Tannerella forsythia are associated with higher risks of esophageal cancer (Peters et al., 2017; Lee et al., 2021).
Endocarditis
The oral commensal bacterium Streptococcus sanguinis possesses virulence factors that allow it to migrate into the bloodstream, bind to the cardiac endothelium, and contribute to
infective endocarditis (Martini et al., 2020).
Chronic Obstructive Pulmonary Disease (COPD)
Several oral bacterial taxa have been detected in lung mucosa of patients with COPD, and similar immune responses between periodontal disease and COPD suggest a common pathophysiology (Hobbins et al., 2017; Bourgeois et al., 2019).
Inflammatory Bowel Disease
Oral strains of Klebsiella are able to colonize the intestine and induce TH1 cells, leading to inflammation (Atarashi et al., 2017).