Tooth decay is one of the most common diseases in the world, and it is almost entirely preventable. Knowing how it forms is the first step in preventing it.
How does tooth decay form?
The bacteria that live naturally in our mouths form a sticky layer on the teeth called plaque. These bacteria use the sugars and carbohydrates we eat to produce acid. The acid dissolves minerals in the enamel, the outermost layer of the tooth. When this happens often, the enamel weakens: first a chalky white spot appears, then a cavity.
The foods that cause decay are mainly sugary, carbohydrate-rich ones. What matters here is frequency rather than quantity: sugary snacks nibbled throughout the day and sugary drinks sipped slowly keep the teeth under constant acid attack.
What makes decay more likely?
- Frequent sugar: Sweets, biscuits, fizzy and fruit drinks, sweetened tea
- Poor oral care: Plaque not being removed regularly
- Lack of fluoride: One of the important causes of decay is a lack of fluoride in water. Fluoride makes enamel more resistant to acid.
- Dry mouth: Saliva neutralises acid and repairs the tooth; when there is less of it, the risk of decay rises.
- Deeply grooved back teeth: Plaque collects in grooves the brush cannot reach.
- Bottle feeding at night: The main cause of early childhood decay in babies.
Symptoms of decay
At first decay causes no symptoms. As it progresses, these may appear:
- Brief twinges with sweet, cold or hot things
- Brown, black or chalky white marks on the tooth
- A hole or rough spot you can feel with your tongue
- Food constantly catching between the teeth, floss snagging or tearing
- Pain that starts by itself or wakes you at night
By the time pain starts, decay has usually come close to the nerve. So rather than waiting for pain, the best approach is a check-up every six months.
How is decay treated?
Treatment depends on how far the decay has progressed:
- Early spotIf no cavity has formed yet, fluoride and good oral care can stop the decay and even reverse it.
- Enamel and dentine decayThe decayed tissue is removed and the tooth is repaired with a tooth-coloured composite filling.
- Decay reaching the nerveIf the nerve is inflamed, root canal treatment is needed, followed by a filling or crown.
- A tooth that cannot be savedIf the tooth is too badly damaged it is extracted and an implant or bridge is planned in its place.
How to prevent decay
- Brush twice a day for two minutes with fluoride toothpaste.
- Use floss or an interdental brush every day; most decay starts between the teeth.
- Have sugary foods with main meals rather than spreading them between meals.
- Quench your thirst with water and cut down on sugary drinks.
- Have fissure sealants applied to children's back teeth.
- See a dentist every six months.
Frequently asked questions
Does tooth decay go away by itself?
Once a cavity has formed, decay does not heal by itself and will progress if untreated. Only early spots that have not yet become cavities can be stopped with fluoride and good care.
Is decay contagious?
The bacteria that cause decay can pass from person to person through saliva. Cleaning a baby's spoon or dummy in your own mouth can pass these bacteria on.
Should decay that does not hurt be treated?
Yes. Pain is a late sign of decay. Painless decay can be treated with a small filling, whereas once pain starts root canal treatment is usually needed.
This article is for general information and is not a substitute for diagnosis or treatment. If you have a complaint, please see your dentist.