The Good, The Bad, and the Unknown: A Closer Look at What’s Happening Beneath the Gums
For decades, periodontal disease was framed as a straightforward behavioral issue: if patients brushed and flossed more consistently, inflammation would resolve and tissues would “tighten back up.”
But as microbiome science evolves, that explanation feels outdated — and honestly, incomplete.
A 2021 review titled “The Good, the Bad, and the Unknown: Microbial Roles in Oral Health and Disease” by Sedghi and colleagues (2021) reframes periodontal disease as a dynamic interaction between oral microbes, the host immune system, and environmental influences rather than a simple accumulation of plaque.
🔗 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8348764/
The review highlights a growing paradigm shift: periodontal disease isn’t caused by bacteria alone — it’s driven by dysbiosis and the host inflammatory response.
🌿 The Good: Beneficial Microbes Aren’t Just Passive
One of the most important takeaways from Sedghi et al. is that many oral bacterial species actively contribute to health. These “commensal” and “mutualistic” microbes:
Help regulate pH and nutrient metabolism
Compete with pathogens for adhesion sites
Interact with host epithelial cells
Contribute to immune tolerance and mucosal stability
These organisms form a balanced ecosystem — and when that ecosystem is stable, periodontal tissues remain healthy even in the presence of plaque.
In other words: biofilm in itself isn’t always harmful — imbalance is.
🔥The Bad: When Microbiome Shifts From Protective to Pathogenic
Dysbiosis usually isn’t a sudden microbial takeover — it’s a gradual shift influenced by:
Host immune response
Genetics
Diet
Hormonal changes
Salivary composition
Smoking
Systemic disease
Local microbial competition
Pathogens such as Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia don’t just increase in number — they change the rules of the environment.
Sedghi et al. describe how pathogenic species can:
Alter local oxygen levels
Release virulence factors
Suppress immune detection
Recruit other harmful organisms
Trigger chronic low-grade inflammation
So the problem isn’t merely “bacteria present” — it’s bacterial behavior and immune dysregulation.
❓The Unknown: The Transitional Phase Before Disease
One of the most clinically relevant points from the paper is this:
👉 Dysbiosis develops long before we see bleeding, radiographic change, or probing depth increases.
This early transitional stage is rarely visible clinically — but it’s detectable through:
Phase-contrast microscopy
Salivary diagnostics
Microbial sequencing
Behavioral and medical risk analysis
This reinforces what modern periodontal protocols already recognize: visual, mechanical, and tactile assessments alone are not enough.
🧠The Host Response: The Real Driver of Destruction
Instead of thinking, “bacteria destroy tissue,” Sedghi encourages a more accurate statement:
➡️ The host inflammatory response to dysbiosis destroys tissue.
Once triggered, this response can:
Break down collagen
Increase vascular permeability
Alter osteoclast activity
Contribute to systemic immune burden
Which brings us to the next point.
🌎Beyond the Mouth: Systemic Implications
Sedghi et al. reinforce what multiple large-scale reviews now support: inflammatory mediators and microbial byproducts can travel beyond the gingival sulcus.
This contributes to overlapping risk in:
Cardiovascular disease
Alzheimer’s and cognitive decline
Autoimmune disorders
Adverse pregnancy outcomes
Diabetes and metabolic dysfunction
This aligns with a growing body of evidence — including papers identifying 57 systemic diseases linked to periodontal infection — reminding us that gum health is a medical issue, not just a dental one.
🧩Clinical implications: Where This Research Point Us
✔ Periodontal care should focus on microbial balance, not just mechanical removal.
✔ “Healthy gums” cannot be defined by the absence of bleeding alone.
✔ Early microbial detection tools should be part of standard periodontal evaluation.
✔ Personalized therapy, including antimicrobials, pH modification, probiotics, home-care targeting, and lifestyle factors, improves outcomes.
Final Thought
When we support the oral microbiome rather than simply attacking plaque, we shift from reaction to prevention, and from maintenance to true healing.
Dysbiosis is reversible.
Chronic inflammation is modifiable.
And periodontal care is evolving.
We’re not just treating gums — we’re supporting whole-body health.
Stay Awesome!
Tosha Kozloski, RDH
Reference:
Sedghi, L., DiMassa, V., Harrington, A., Lynch, S., & Martel, J. (2021). The Good, the Bad, and the Unknown: Microbial Roles in Oral Health and Disease. Journal of Molecular Biology. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8348764/
