Cavities and tooth decay
A cavity is a hole in a tooth, caused by decay. Decay is slow, and often silent at first, which is why small cavities are easy to treat and large ones are not. Here is how decay works, and how to stop it early.
How a cavity forms
Your mouth is home to bacteria, including bacteria that feed on the sugars in food and drinks. As they feed, they produce acid. That acid sits on your teeth in a sticky film called plaque, and over time it softens and breaks down the enamel, the hard outer layer of the tooth. Once the enamel is breached, a cavity has formed.
How decay progresses
Left alone, decay works inward: through the enamel, into the softer dentin beneath it, and eventually toward the pulp, the living center of the tooth that contains its nerve. That is why a cavity that causes no feeling at all can become a painful toothache later. The pain usually starts when decay gets close to the nerve. In its latest stages, decay can lead to an infection at the root of the tooth, called an abscess.
Signs to watch for
- Sensitivity to sweet, hot, or cold foods and drinks
- Pain or a twinge when you bite down
- A visible hole, pit, or dark spot on a tooth
- Food catching in the same place again and again
- Bad breath that does not clear (more on that in our bad breath topic)
Early decay often has no signs at all. That is why regular checkups and X-rays matter: they catch decay while it is still small.
What raises the risk
- Frequent sugary drinks and snacks. How often you have them matters, not just how much.
- Dry mouth, since saliva helps wash and protect your teeth.
- Not cleaning between your teeth, where a brush cannot reach.
- Deep grooves in back teeth, which trap plaque.
- Older fillings and crowns with worn edges, where bacteria can collect.
How cavities are treated
The right treatment depends on how far the decay has gone, and your dentist will walk you through it. A small cavity is usually treated with a filling: the decayed part is removed, and the space is filled. A tooth weakened by a larger cavity may need a crown to protect it. If decay reaches the nerve, the choices are generally root canal treatment to save the tooth, or removing the tooth if it cannot be saved. Caught early, treatment is simpler, more comfortable, and less expensive. That is the whole argument for not waiting.
Preventing decay
- Brush twice a day with fluoride toothpaste.
- Clean between your teeth every day, with floss or interdental brushes.
- Limit how often you have sugary drinks and snacks through the day.
- Drink water. It rinses your mouth and supports saliva.
- Keep regular checkups and cleanings, so small problems are found while they are small.