What makes teeth ill
Almost everything begins in the same place: with a layer of bacteria.
Several hundred species of bacteria live in the mouth. That is not a lack of hygiene but the normal state: the oral flora belongs to the body just as the gut flora does, it occupies niches that pathogens would otherwise take, and most of its inhabitants do no harm. Problems do not arise because bacteria are there, but because some of them are given too much peace.
How a biofilm arises
A few minutes after brushing, a wafer-thin film of saliva components settles on the tooth surface. It is unavoidable and harmless in itself. The first bacteria settle on it; they form sticky sugar compounds with which they hold on and to which further species dock.
What develops from this is not an accumulation but a structure. The bacteria build a shared protective layer, arrange themselves in strata according to their oxygen requirements and exchange substances with one another. After about two to three days the community is mature and, on the inside, largely insensitive to rinses.
That is the reason why no mouthwash removes plaque. It reaches the outer layer; the interior remains untouched. A biofilm is destroyed mechanically — with a brush, an interdental brush or dental floss — or not at all.
From soft to hard
If the plaque stays where it is, it takes up minerals from the saliva and hardens. The process begins after one to two days; after a few weeks the layer is solid. Tartar is not itself a cause of disease, but its rough surface is an ideal base for new soft plaque, and that then lies in direct contact with the gums.
Most tartar forms where the salivary glands open: on the inner surfaces of the lower incisors and the outer surfaces of the upper molars. How quickly someone forms tartar is to a considerable extent a matter of predisposition — the composition of saliva is individual.
Two paths, one origin
Two different diseases arise from the same biofilm, depending on which bacteria prevail and where the plaque lies:
- caries arises on the tooth surface. Bacteria turn sugar into acid, which dissolves minerals out of the enamel.
- Gum inflammation and periodontitis arise at and below the gum line. Here different species of bacteria are involved, and the damage is caused not by acid but by the body's defensive reaction to the bacteria.
That is why the same measure — removing plaque regularly — protects against both, and why it is not enough to brush only the surfaces you can see.
What shifts the balance
- Frequent intake of sugar. It is not the amount that decides but how often. Every contact starts an acid attack of about 30 minutes.
- Little saliva. Saliva rinses, neutralises acid and returns minerals. Medication, mouth breathing and some illnesses reduce it.
- Smoking. Impairs the blood supply to the gums and shifts the composition of the bacteria unfavourably.
- Niches. Protruding filling margins, crowded teeth, braces and the margins of dentures offer shelter from the brush.
- A weakened defence through diabetes, stress or medication that suppresses the immune system.
The essentials at a glance
- Dental plaque is a biofilm: an ordered community of bacteria in a protective layer they build themselves. It cannot be rinsed away, only removed mechanically.
- After about 24 to 48 hours the soft plaque begins to harden. Once it is tartar, no brush removes it any more.
- Caries and gum inflammation have the same cause, but different bacteria and different locations.
- A mouth is never free of germs, and it is not supposed to be. It is not about eradication but about a balance.
Answered briefly