caries

Caries is not an infection you catch, and not a matter of fate. It is the result of an imbalance that persists over months and years: more minerals leave the tooth than return to it.

The process

Bacteria in the plaque process sugar and give off acid in doing so. The pH value at the tooth surface falls. Below a value of about 5.5 the enamel begins to give up calcium and phosphate — it is decalcified.

Then the counter-movement begins: saliva neutralises the acid and returns minerals, which are deposited again. This to and fro takes place every day, several times. As long as the two directions balance, nothing happens.

If the balance tips lastingly towards breakdown, caries arises. A single piece of cake is not enough for that. What is needed is the frequency: anyone who eats something sweet ten times across the day keeps the tooth in the acidic range ten times for half an hour — that is five hours of breakdown a day.

The stages

1. Initial caries. A chalky-white, matt spot. The enamel is decalcified but still intact. This stage is reversible — with fluoride, good cleaning and less frequent sugar, the enamel can fill up again.
2. Enamel caries. The surface breaks in and a small hole forms. From here on it is filled; it no longer closes by itself.
3. Dentine caries. The caries reaches the softer tooth tissue beneath the enamel and spreads there faster — often wider than the hole at the surface suggests. Sensitivity to sweet and cold things begins.
4. Close to the nerve. Persistent pain, pain on warmth, sensitivity to tapping. Now it is about saving the tooth nerve, often about a root canal treatment.

What is remarkable about this sequence is how late the pain comes. The first two stages are completely free of complaints. Anyone who waits until something hurts skips exactly the part in which a simple solution would have been possible — and that is the real reason for regular check-up appointments.

Where it arises most often

• In the fissures, the grooves of the chewing surfaces. Above all in children and adolescents shortly after the tooth comes through.
• Between the teeth. The most common place in adults. Not recognisable with the eye — an X-ray image is needed for that.
• At the tooth neck, once the gum has receded. The exposed root surface has no enamel and is attacked at a higher pH than the tooth above it.
• At the margins of fillings, crowns and bridges.

What really protects

• Fluoride. The best-established single measure. It makes the enamel more resistant to acid and promotes the re-deposition of minerals.
• Limit the number of contacts with sugar. More effective than reducing the amount. Better to have sweet things with a meal than spread across the day.
• Remove plaque daily, including the interdental spaces.
• Sealing of the chewing surfaces in children and adolescents.
• Sugar-free chewing gum after eating. It stimulates the flow of saliva, and saliva is the body's own buffer. Xylitol additionally has a slightly inhibiting effect on the bacteria.
• Enough saliva. Anyone suffering from dry mouth has a markedly increased risk and should raise the subject.

What does not protect: mouthwashes as a replacement for brushing, whitening toothpastes and going without fluoride.