The classic children’s book about two little tooth trolls with pickaxes may be charming—but from a medical perspective, the image is outdated. Tooth decay is not the destructive work of tiny monsters; it is a biochemical process..
Why does this distinction matter to you? Quite simply: once you understand that cavities are a metabolic disease of dental plaque, you also understand how to stop the process before a drill becomes necessary. Let’s take a look under the microscope.
The development process
1. The crime scene: Biofilm, not just “plaque”
Billions of bacteria live on your teeth. This is completely normal—and healthy. These microorganisms organize themselves into a complex network known as a biofilm (formerly called plaque). As long as this ecosystem remains balanced, your teeth stay healthy. Problems arise only when we “feed” the wrong bacteria.
2. The fuel: Sugar is the engine
Certain bacteria within the biofilm (e.g., streptococci and lactobacilli) thrive on fermentable carbohydrates. This includes not only obvious table sugar but also fructose, starch (chips, crackers), and hidden sugars in processed foods.
The chemical process:
- The bacteria metabolize sugar extremely quickly.
- As a waste product, they produce organic acids (such as lactic acid).
- These acids rapidly lower the pH level in the mouth.
3. The attack: Demineralization
Tooth enamel is the hardest substance in the human body—but it has one weakness: acid. When the pH level drops below a critical threshold (approximately 5.5 to 5.7), minerals such as calcium and phosphate dissolve out of the enamel structure. The tooth becomes porous. This is the beginning of tooth decay—long before a visible cavity appears. We call this early stage initial caries (often visible as a chalky white spot).
4. The rescue: Your saliva as the repair team
Under normal circumstances, the body has its own repair system: saliva.
- Buffering: It neutralizes acids and raises the pH level again.
- Remineralisation: It is saturated with calcium and phosphate and redeposits these building blocks into the enamel.
The frequency problem: This repair process takes about 30 to 60 minutes. If you snack constantly or sip sugary drinks (including diluted juices) throughout the day, saliva cannot keep up with the repairs. The balance tips permanently in favor of destruction.
Anatomical risk factors: Where the brush
Not every tooth is equally at risk. Cavities almost always begin in so-called predilection sites (niches):
- Fissures: The deep grooves on the chewing surfaces of molars are often narrower than a single toothbrush bristle. Bacteria can “work” there undisturbed for months.
- Crowding: Overlapping or tightly spaced teeth prevent effective cleaning.
A word about “contagion” (transmission)
For years, parents were told: “Never lick your baby’s spoon!” It is true that cavity-causing bacteria can be transmitted through saliva. However, modern studies show that transmission alone does not cause tooth decay. The environment is what matters most. If your child has a low-sugar diet and good oral hygiene, cavity bacteria cannot multiply explosively—even if they have been transmitted. Our recommendations: Hygiene is important, but panic is unnecessary. Focus primarily on healthy dietary habits.
Conclusion: Cavities are not fate. They are the result of an imbalance between acid attacks and the repairing power of your saliva. With proper fluoride use and sufficient breaks between meals, you can maintain this balance. That is how you prevent tooth decay—long before treatment becomes necessary.