For years we've had red wine and coffee drummed into our heads as the main culprits for yellowed teeth. And it turns out we do the greatest damage ourselves - and precisely at the moment when we think we're caring best. Brushing your teeth right after eating, as a habit, damages and darkens the enamel more than a single glass of wine.

The logic is unexpected but clear once understood. After acidic food or drink, the mouth temporarily lowers its acidity, and the enamel - the outer protective layer of the tooth - becomes more vulnerable. If you scrub with a brush at exactly that point, you create friction on a surface that hasn't yet returned to balance.

The dentist Eugenia Cervantes explains it without mincing words: after acidic things like citrus, fizzy drinks, wine or tomato, the tooth enamel becomes temporarily more sensitive because the pH in the mouth drops. Brushing immediately can trigger gradual wear of the enamel through friction on a surface that is still recovering. Her advice - wait thirty to sixty minutes before you brush.

A second expert, the dentist Antonio Longo, confirms the same from another angle. Enamel is a barrier, he says, and after acidic products that surface becomes prone to erosion and wear. Vigorous brushing at that moment causes greater damage and increased tooth sensitivity.

For coffee there's a special trick. If you drink water after it, you remove the pigments before they settle on the enamel. And don't sip coffee for hours - that's like keeping your teeth soaked in colour all morning.

The list of culprits for dark teeth is longer than we think: black tea, red wine, cola, curry, soy sauce, balsamic, berries, beetroot, even dark chocolate. But the point isn't to give up all of that. The point is simpler - sometimes the least you can do for your teeth is not to brush them at the wrong moment. That's all.