The oldest organ in your mouth isn’t what you think (2025)

3.5 billion years of evolution gave you a built-in shield against cavities and gum disease.

Here’s why it no longer works.

Biofilms are often referred to as the “skin” of the tooth, a simple and ubiquitous layer that adheres to hard surfaces like teeth. However, this description fails to capture the true essence of biofilms as fundamental biological systems.

Biofilms are far older than the human species, originating in the earliest stages of life on Earth. They represent one of the first forms of organized life and have evolved over billions of years to serve as critical survival mechanisms for microorganisms.

Yet, in today’s world, the biofilm faces a profound mismatch with modern environmental conditions, leading to a host of oral health issues. Understanding biofilms as primordial organ systems that evolved under very different conditions can shed light on how we might better care for them in today’s world.

The Ancient Origins of Biofilms

• Biofilms are among the earliest life forms on Earth, with fossilized microbial mats found in stromatolites dating back 3.5 billion years.
• These early biofilms were built by prokaryotic organisms like cyanobacteria—life forms that thrived in low-oxygen, extreme environments.
• The formation of biofilms allowed these microorganisms to shield themselves from harmful ultraviolet radiation, prevent desiccation (drying out), and share nutrients efficiently.
• Biofilms also provided a mechanism for genetic exchange, enhancing the adaptability of these early life forms.

Magnesium (here’s the link to the one I take) played a crucial role in enabling these early biological systems to function:

• It activates enzymes, transfers energy (via ATP), and stabilizes DNA and RNA.
  
• Alongside iron and phosphorus, magnesium made life possible.

Biofilms weren’t just shields—they were thestepping stones to multicellular life. Their structure enabled cooperation, communication, and early complexity.

Biofilms and the Oral Microbiome

In humans, the oral biofilm is a vital component of our oral microbiome. It serves as a physical shield for the teeth, providing protection against harmful bacteria that could cause decay or gum disease.

This biofilm is not just a passive layer; it has active functions that promote oral health. It contains antimicrobial agents and hosts immune responses, including antibodies, to help defend against pathogens.

The biofilm also helps regulate pH levels in the mouth and assists in the remineralization of the tooth by transferring calcium from saliva to areas of the tooth that have been demineralized.

Biofilm is dynamic. Bacteria within the biofilm communicate with each other through quorum sensing, a process that allows them to coordinate their activities, adjust to changing environmental conditions, and maintain a healthy balance. The biofilm thus acts as a regulator of the oral ecosystem, ensuring that beneficial bacteria thrive while harmful ones are kept at bay.

The Mismatch with Modern Life

Despite their evolutionary success, biofilms now face challenges they were never designed for:

• Dietary Changes:Modern diets are rich in sugars and fermentable carbs. Harmful bacteria thrive and create acid, causing enamel loss.
  
• Processed Foods:High in refined sugars, these promote the overgrowth of damaging bacteria.
  
• Dry Mouth:Caused by dehydration, medications, and mouth breathing. This lowers pH and favors harmful strains.
  
• Frequent Snacking:Constant food exposure prevents biofilm recovery.
  
• Oral Care Products:
  For decades, oral care has focused on sterilization. But the oral microbiome is a living organ system—it needs balance, not eradication. This is why I co-foundedFygg (Feed Your Good Guys). Alcohol, triclosan, detergents, emulsifiers, and even “natural” essential oils disrupt the ecosystem we depend on. In trying to clean our mouths, we’ve created microbial sabotage.

This mismatch between the biofilm’s evolutionary design and modern living conditions leads to a host of oral health problems, including cavities, gum disease, and other systemic effects.

Mismatch Diseases: What Happens When the Biofilm Can’t Adapt

• Cavities (Dental Caries):Sugar feeds acid-producing bacteria that break down enamel.
  
• Gum Disease (Gingivitis and Periodontitis):Microbial imbalance causes inflammation and infection.
  
• Rebound from Harsh Products:Overuse of antibacterial mouthwash can destroy good bacteria—causing imbalance.
  
• Dry Mouth and pH Issues:A dry, acidic environment feeds pathogens.
  
• Systemic Effects:Oral pathogens may enter the bloodstream and contribute to diseases like Alzheimer’s and heart disease.

Supporting the Biofilm: The Path Forward

Instead of focusing on killing the biofilm with harsh chemicals or aggressive brushing, we should aim to support and nourish it. Biofilms are living systems that have evolved over billions of years, and with the right conditions, they can continue to protect the teeth and maintain oral health.

Here are some strategies for supporting the biofilm:

• Gentle Brushing: Brushing should not be about scrubbing away the biofilm. Instead, it should be focused on gently disorganizing the bacteria to reset the balance. Using a soft-bristled toothbrush and non-abrasive toothpaste ensures that the biofilm is not disrupted too aggressively.
• Proper Hydration: Saliva plays a critical role in maintaining the biofilm. Drinking plenty of water and avoiding dry mouth helps keep the biofilm hydrated and functioning properly.
• Healthy Diet: A diet low in processed sugars and high in nutrients and minerals (like magnesium) and electrolytes helps support the healthy bacteria in the biofilm, allowing it to thrive and protect the teeth.
• Oil Pulling: This practice involves swishing oil, often coconut or sesame, in the mouth to help cleanse and maintain the biofilm. Unlike abrasive brushing, oil pulling doesn’t scrub or remove the biofilm but helps to thin it gently. By doing so, it encourages a balance in the oral microbiome, allowing beneficial bacteria to thrive while preventing the overgrowth of harmful bacteria. It’s a simple, natural way to support oral health without disrupting the biofilm’s protective role.
• Use Nourishing Oral Care Products: It’s essential to choose products that nourish the oral microbiome. The right products, including non-abrasive toothpaste andessential oil-freetoothpaste, support the biofilm’s health by maintaining a balanced, thriving environment for the beneficial bacteria. These products help reinforce the biofilm’s protective role rather than stripping it away.

Biofilms are far more than a simple layer on the tooth—they are ancient systems that have played a critical role in the survival of life on Earth. The biofilm in our mouths is a living organ system that evolved to protect us from pathogens and maintain oral health. However, the modern environment has created a mismatch between the biofilm’s evolutionary design and the stresses it now faces.

The biofilm is there for a reason—to protect and balance your mouth. Treat it with respect, and it’ll continue to do its job.

-Dr. B

P.S. I did a brand new podcast interview last week. Give it a listen and let me know what you think!

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