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Tooth Decay and Cavities: How They Start and How to Prevent Them
Tooth decay is the most common health condition worldwide. Learn how cavities form, the early signs, how fillings work and the daily habits that prevent decay.
Quick answer
Tooth decay happens when bacteria in plaque turn sugar into acid that slowly dissolves tooth enamel, creating a cavity. Early decay often has no symptoms, so regular check-ups matter. Brushing twice a day with fluoride toothpaste, cleaning between teeth, limiting sugary food and drinks to mealtimes and regular dental visits prevent most decay. Small cavities are repaired with a filling.
According to the World Health Organization, untreated tooth decay in permanent teeth is the single most common health condition in the world. Almost all of it can be prevented.
How a cavity forms
- Plaque, a sticky film of bacteria, builds up on teeth.
- When you eat or drink sugar, the bacteria produce acid.
- Repeated acid attacks dissolve minerals from the enamel.
- Over time, a hole (cavity) forms and can spread into the softer dentine and the nerve.
Signs of decay
Early decay often has no symptoms. Later signs include:
- Sensitivity to sweet, hot or cold food and drink
- Toothache
- Visible holes, pits or brown and black spots
- Pain when biting
Treatment
- Very early decay can sometimes be reversed with fluoride and better cleaning.
- Cavities are cleaned and filled. Tooth-coloured fillings are common.
- Deep decay reaching the nerve may need root canal treatment or, if the tooth cannot be saved, an extraction.
Prevention: daily habits
- Brush twice a day for two minutes with fluoride toothpaste.
- Spit, don't rinse, after brushing.
- Clean between teeth daily with floss or interdental brushes.
- Keep sugar to mealtimes. How often you have sugar matters more than how much.
- Choose water over juice, fizzy and energy drinks.
- Chew sugar-free gum after meals to boost saliva.
- Have regular check-ups, as recommended by your dentist.
Frequently asked questions
Do dates and honey cause cavities?
Yes, they contain sugars and can stick to teeth. Enjoy them with meals rather than as frequent snacks, and drink water afterwards.
Can a cavity heal on its own?
Once a hole has formed, it cannot heal. Only the earliest stage, before a cavity forms, can sometimes be reversed.
