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How Well Do You Know the Oral Pathogens?

Updated: Jan 12, 2022

Over 700 bacteria live in your mouth. Most of these oral bacteria are harmless and some are even beneficial. But certain bacterial strains lead to tooth decay, gum disease, and a host of other diseases affecting all parts of the body, not just the mouth.

These detrimental, high-risk oral bacteria can elevate your risk of diabetes, cardiovascular disease, cancer, Alzheimer's disease, pregnancy complications, just to name a few.

Periodontal bacteria can invade the walls of your arteries, eventually resulting in a thickening of the artery wall, and if left untreated, leads to a 3x greater risk of dying from a stroke and a 2x greater risk of dying of a heart attack. 50% of heart attacks and strokes are triggered by oral bacteria that live in your mouth. These sobering statistics are proof of the oral systemic connection. And these are only concerning the heart! The extent of the damage that these pathogenic bacteria cause to the rest of the body is just as significant. With more than 700 bacteria in your mouth, it’s no wonder that some of these bacteria can cause issues beyond oral health.

Fortunately, Dr. Tom Nabors is at the helm of Direct Diagnostics, leading the way in pathogen bacteria research. Dr. Nabors is a pioneer of the oral systemic health movement and has more than 45 years of this experience under his belt. He has dedicated his career to examining the role of oral pathogenic bacteria and their destructive effects. He is the first recipient of The American Academy for Oral Systemic Health’s lifetime achievement award for his contributions to the field. He is the founder and former Chief Dental Officer of Oral DNA Laboratories and also the founder of the first CLIA & CAP certified laboratory that uses DNA-PCR testing for both general and oral medicine.

Why do we need to focus on oral pathogens?

Numerous studies have been published by the scientific community that exhibit the damaging outcomes associated with high levels of specific bacteria in the mouth that affect the whole body as well as oral health. This is now recognized as the oral systemic connection.

The current standard of care determines a patient’s level of health by assessing obvious symptoms. In other words, it waits until an issue exists before it seeks to help. The goal of conventional dentistry and medicine is to treat the sick and offer surgery and drugs as the solution. The oral systemic approach goes deeper, searching for the root causes of disease. Rather than adopting the traditional wait-and-see approach, oral systemic methodology starts with diagnostics. Advanced testing provides a solid first step in creating an effective preventative care plan.

The oral systemic movement is backed by substantial and growing scientific data. The oral systemic approach reduces and eliminates oral inflammation, which is one of the most significant root causes of heart disease, stroke, diabetes, and other diseases. Supplying diagnostics directly to dental professionals makes Direct Diagnostics an important place to start in the oral systemic health care process.

The mouth is the gateway to the rest of your body

The mouth is the gateway to the rest of the body. What is happening in your mouth is a precursor for the condition of other systems in your body. Direct Diagnostics provides tests that can be used by both dental and medical practitioners to create an accurate diagnosis and personalized treatment plan for each patient. Early detection of pathogenic oral bacteria, identification, and successful treatment of specific pathogens will lead to improved oral health and the health of the whole body. By providing oral systemic care to your patients, you have the opportunity to grow your practice and deliver optimal results.

But first, we need to understand the oral pathogens.

The importance of bacterial balance in oral systemic health

Imagine a drone’s view of New York City streets during rush hour. Now transfer this image to a microscopic scale. This should provide a good visualization of the microbial community within our bodies. With so many facets working together, it’s easy to realize the importance of such a network. Because it performs so many important roles in enabling the smooth daily operations of the human body, the microbiome is even categorized as a supporting organ.

Each person has a microbiota network that is completely unique to them, as specified by their DNA. And when we talk about bacteria, we need to recognize the dual nature of bacteria. The microbiome in our bodies is made up of both beneficial and potentially dangerous bacteria. The majority have a symbiotic relationship, while some are harmful. Balance is essential for the microbiome and the presence of pathogenic bacteria upsets this balance, to say the least. A disturbance in the balance of the microbiome creates dysbiosis and makes the body more susceptible to disease. The majority of us live in a world where this balance is constantly threatened. Diets lacking adequate nutrition, use of antibiotics, poor sleep, stress are just a few of these threats. These types of threats open the door for oral pathogenic bacteria.

It's no surprise that the mouth is a breeding ground of information and possible risk, with the amount of microorganisms dwelling there. Most oral bacteria are innocuous, and some are even useful, but other bacteria cause tooth decay, gum disease, and a variety of other disorders that affect both the mouth and the rest of the body. Periodontal disease is caused by pathogenic oral bacteria. This harmful bacteria travels through the bloodstream, reaching the entire body. Below are just a few of the examples of the serious complications associated with pathogenic bacteria traveling throughout the body:

Cancer: Bacteria in the mouth are associated with oral, esophageal, lung, colorectal, pancreatic, and breast cancers.

Neurodegenerative disorders: Pathogenic oral bacteria negatively affects the brain and has been linked to Alzheimer’s Disease.

Adverse pregnancy outcomes: Women with severe periodontal disease were found to have seven times the risk of giving birth early, than women with healthy gums. Low birth weight and pre-eclampsia have also been associated with severe periodontal disease.

Cardiovascular disease: Periodontal Disease is directly linked to arterial inflammation which in turn is responsible for strokes, heart attacks, and atrial fibrillation. Up to 50% of heart attacks and strokes are triggered by pathogenic oral bacteria.

A key first step in the oral systemic healing process is to get a comprehensive picture of a patient's microbiome and identify any imbalances as well as the existence of any high-risk pathogenic microorganisms. This is when diagnostics come into play.

What are the High Risk Five?

We now have scientific data that connects these five bacteria with an extensive list of serious health issues. These bacteria can be found and identified in the mouth and travel throughout the body. This phenomenon directly demonstrates the oral systemic connection.

Aggregatibacter actinomycetemcomitans (Aa)

This bacteria is a main culprit for rapid alveolar bone loss in both adults and children, severe periodontitis, and dental implant failure. And to go beyond the mouth and bones, this pathogen also increases risk for cardiovascular disease, ischemic stroke, brain abscesses, and heart infections. In addition, it is linked to rheumatoid arthritis, Alzheimer’s Disease, cancer, high blood pressure, and adverse pregnancy outcomes.

Porphyromonas gingivalis (Pg)

Porphyromonas gingivalis is a primary cause of alveolar bone loss, periodontitis and implant failure. Research studies have shown this pathogen also contributes to artery plaque, rheumatoid arthritis, diabetes, cancer, high blood pressure, adverse pregnancy outcomes, Alzheimer's Disease, and other inflammatory diseases.

Treponema denticola (Td)

This pathogen is a major contributor of periodontitis and implant failure (peri-implantitis). It feeds off of stress and has demonstrated its association with diabetes, kidney disease, adverse pregnancy outcomes, artery plaque, high blood pressure, dementia, and Alzheimer's Disease.

Tannerella forsythia (Tf)

Tannerella forsythia is a primary cause of periodontitis and implant failure (peri-implantitis). Other health issues it causes are artery plaque, Alzheimer’s Disease, heart attack, cancer, adverse pregnancy outcomes, diabetes, high blood pressure, atherosclerosis, and kidney disease.

Fusobacterium nucleatum (Fn)

This pathogen tends to facilitate the movement of other oral pathogens into the circulatory system. It is associated with periodontitis, implant failure, preterm birth, pre-eclampsia, low birth weight, artery plaque, atherosclerosis, cancer, and gut dysbiosis. It also adheres to and invades endothelial cells.

Oral pathogens travel to all parts of the body

Bacteria in your mouth travels through your bloodstream, and brings disease risk to the rest of the body. This is the oral systemic connection in action! If you’ve ever doubted the power of proactive dental care, we’d like to eliminate that doubt. These harmful bacteria spread through the body with such simple acts as brushing your teeth and chewing! Pathogenic oral bacteria can be passed from one person to the next through common, everyday actions such as sharing food and drinks, and even kissing.

The most significant pathogenic bacteria for chronic periodontitis is P. gingivalis. When Pg is left unchecked and allowed to colonize, it promotes inflammation and weakens the host defense. These changes in turn cause alterations in the subgingival microbiota, which creates dysbiosis.1

Pg and the mouth-brain connection

“Oral bacteria have been implicated in the development of Alzheimer's disease and dementia.” - The American Academy for Oral Systemic Health

Porphyromonas gingivalis (Pg) is associated with:

  • alveolar bone loss

  • periodontitis and implant failure

  • artery plaque

  • rheumatoid arthritis

  • diabetes

  • cancer

  • high blood pressure

  • adverse pregnancy outcomes

  • Alzheimer's Disease

  • other inflammatory diseases

To expand upon the causations listed above, it’s important to point out that periodontal disease is a greatly important risk component for Alzheimer’s disease. The pathogenic bacteria, Porphyromonas gingivalis (Pg), breaks through the blood-brain barrier, a network of dense cells that protects the brain from dangerous elements. Once Pg breaches this barrier, it can cause pathological changes.

Heavy colonization of Pg in the brain has been observed in deceased people with Alzheimer’s disease.2

Aa is connected to pancreatic cancer and rheumatoid arthritis

Almost half of people suffering from rheumatoid arthritis have evidence of infection by Aggregatibacter actinomycetemcomitans (Aa), compared to 11% in healthy individuals.3

People with Aa oral infection are at least 50% more likely overall to develop pancreatic cancer.4

Periodontal disease and COVID complications

COVID-19 patients with periodontal disease have:

  • 8.8 x higher chance of death

  • 3.54 x higher chance of ending up in the ICU

  • 4.57 x higher chance of ending up on a ventilator

Direct Diagnostics is your destination for identifying oral pathogens

We have scientific proof that strokes and heart attacks are avoidable through targeted, preventative care. And the benefit of testing goes beyond heart health. This process begins with diagnostics. Identifying the bacterial culprits is the crucial first step in creating a tailored treatment plan.

Saliva testing is effective in assessing your bone and gum health. Salivary diagnostics provides definitive data about the presence of any pathogenic bacteria. This data is used to create tailored treatment plans for each patient.

It is not only the general presence of oral pathogenic bacteria in the mouth, but even more so, the precise identification of which bacteria are present in the mouth. Specific strains of pathogenic bacteria have been shown to be directly responsible for specific diseases.

Not only is testing step one, but continued testing throughout treatment shows the process of healing. Each step of the way improvement can be tracked through repeated diagnostics.

Our HR5 saliva test was created to bolster the scientific foundation of oral systemic protocols. It can empower your practice to join the movement and provide powerful diagnostics that yield conclusive answers.

Here are 10 Reasons to use our HR5 test:​

  • Focused

  • Affordable

  • Accurate

  • Quantitative

  • Patient Friendly

  • Provider Friendly

  • Easy to Read

  • Fast Turnaround

  • User-friendly Software

  • Saliva (just saliva)

We now know that inflammation is the most common pathway that drives the disease process. Pathogenic oral bacteria triggers the inflammatory process and inflammation, in turn, creates disease. There are many root causes of inflammation, three of which must be treated by a dentist, and specifically a dentist that understands and practices an oral-systemic approach. This demonstrates the importance of a medical and dental collaboration to address these root causes of inflammation.

We offer tools that conventional medicine does not! Direct Diagnostics is a clinical laboratory and biotechnology company that is advancing the field of molecular testing and transforming salivary diagnostics. We are developing the next generation of saliva tests for infectious disease and pathogens found in the mouth and periodontia.


1. Hajishengallis et al., 2011; Maekawa et al., 2014


3. Darrah, E. (2017, January 23). Gum disease linked to rheumatoid arthritis. John Hopkins Rheumatology. gum-disease-linked-to-rheumatoid-arthritis/

4. Karpiński T. M. (2019). Role of Oral Microbiota in Cancer Development. Microorganisms, 7(1), 20.

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