700 species, systemic consequences, and a diagnostic signal hiding in saliva
Diverse and stable: most species are harmless or helpful.
Diversity falls and pathogenic species take over. This shift, not bacteria themselves, drives disease.
For most of its history dentistry treated bacteria as the enemy: scrape, sterilize, repeat. Part III replaces that idea with ecology, and asks what an oral community can reveal about the rest of the body.
A healthy mouth is not a sterile one. It is a stable, diverse community of roughly 700 species3. Dysbiosis, a shift in that balance, is what drives disease, and salivary testing can now turn an invisible ecosystem into a clinical measurement.
The most newsworthy material in the book sits here. Fusobacterium nucleatum, an oral organism, is enriched in colorectal tumors6 and appears to promote cancer growth through a specific adhesin7. A prospective study found that carriage of two oral pathogens was associated with meaningfully higher later risk of pancreatic cancer, a cancer usually found too late8. Part III is careful about what these signals mean, what they do not mean, and how a clinician should put a risk finding in front of a patient without frightening or falsely reassuring them.
It ends with restoration: why the eliminative approach has a ceiling, what the evidence shows for specific oral probiotics, how to read a probiotic label, and how antiseptics deplete the nitrate-reducing species described in Part II15.
700 Species and Counting
What a healthy oral community looks like, what dysbiosis is, and how salivary testing measures it. Includes a reference guide to the major oral pathogens.
When Bacteria Become a Cancer Warning
F. nucleatum and colorectal cancer, the pancreatic cancer data, and what an elevated salivary result does and does not mean.
Rebuilding the Ecosystem
Cultivation instead of sterilization: probiotics, diet, label literacy, and protecting the species that make nitric oxide possible.
The pathogen map
Three oral pathogens, six conditions, and the evidence connecting them. Select an organism or a condition.
Select an organism or a condition.
Each line is a published finding, labeled by the strength of its evidence. Association is not causation; the label tells you what kind of evidence stands behind each line.
Porphyromonas gingivalis
A principal periodontal pathogen. It produces gingipains, protein-cutting enzymes, and an enzyme (PPAD) that citrullinates human proteins.
- Cardiovascular diseaseAssociation
DNA of P. gingivalis detected inside human atheromatous plaque.4
- Alzheimer's diseaseAssociation + animal
Gingipains found in Alzheimer's brain tissue, tracking with tau; oral infection in mice reached the brain.5
- Pancreatic cancerProspective
Oral carriage associated with higher later risk of pancreatic cancer.8
- Rheumatoid arthritisMechanistic
Its PPAD enzyme citrullinates human proteins, the targets of rheumatoid autoantibodies.10
Fusobacterium nucleatum
A common oral anaerobe that bridges other species in dental plaque. Its FadA adhesin binds E-cadherin on human cells.
Aggregatibacter actinomycetemcomitans
Associated with aggressive forms of periodontitis. It produces leukotoxin A, which damages white blood cells.
Cardiovascular disease
Atherosclerosis and blood-vessel function.
- P. gingivalisAssociation
DNA of P. gingivalis detected inside human atheromatous plaque.4
Alzheimer's disease
Progressive neurodegeneration with amyloid and tau pathology.
- P. gingivalisAssociation + animal
Gingipains found in Alzheimer's brain tissue, tracking with tau; oral infection in mice reached the brain.5
Colorectal cancer
Cancer of the colon and rectum.
Pancreatic cancer
Usually diagnosed late, when treatment options are limited.
Rheumatoid arthritis
Autoimmune joint disease marked by antibodies to citrullinated proteins.
Adverse pregnancy outcomes
Including preterm birth and stillbirth.
- F. nucleatumCase report
One documented case traced an oral strain to a term stillbirth.12
What the evidence supports
Where the book draws the line
- A positive salivary result is a risk signal, not a diagnosis.
- Probiotic evidence is strain-specific; the book reads the trials rather than the marketing.
- Association is reported as association.
Be the first to know.
Hear when Oral Intelligence is available, and receive early excerpts before launch. Nothing else.
Published by Keystone & Arch, New York.