How to Tell if You Have a Cavity

What are the early signs of a cavity?

Usually the first sign is a chalky white patch on the enamel, with no pain. Next, the patch may darken to brown or black. A short twinge with sweet or cold food often follows. Food that catches in the same gap after every meal is another common clue.

Why early decay rarely hurts

Enamel has no nerves, so early decay sends no warning. Pain starts only once acid reaches the softer dentine, which connects to the nerve. By then the damage has often become a true hole.

Which teeth are most at risk?

Back teeth top the list, because their deep grooves trap plaque. Contact points between teeth come next, since a brush cannot reach them. In older adults, exposed roots are vulnerable too. Old fillings with worn edges can also hide fresh decay.

Enamel

The hard outer layer of the tooth, where decay begins as a loss of minerals.

Dentine

The softer layer beneath the enamel; decay at this depth brings sensitivity.

Pulp

The nerve and blood vessels at the centre of the tooth.

White spot lesion

The earliest visible stage of decay, which can still remineralise.

Bitewing X-ray

A small X-ray that shows decay between the back teeth.

How to tell if you have a cavity at home

If you are wondering how to tell if you have a cavity, start with a mirror, bright daylight and dry teeth. Look for chalky, brown or dark areas in back-tooth grooves and along the gumline. Then pay attention to which tooth reacts to sweet food. The checklist below keeps the routine simple.

1. Dry your teeth first, because wet enamel hides white spots.
2. Check back-tooth grooves for dark lines.
3. Run your tongue along each tooth for rough edges.
4. Floss and note any gap where it shreds or catches.
5. Write down which tooth twinges with sweet or cold food.
6. Book a check-up if any clue persists.

What a self-check cannot show

A mirror cannot see between teeth or under old fillings, where many cavities grow unnoticed. So a clear result at home is reassuring, but it is not a diagnosis. Our sensitive teeth page covers other causes of twinges.

Cavities between teeth

Decay at a contact point spreads sideways inside the tooth, often unnoticed until a corner chips. So how can you tell if you have a cavity there? Usually you cannot; instead, a bitewing X-ray finds it early.

What happens as decay gets deeper?

Decay moves inward in recognisable stages, and the symptoms change at each one. It starts as a white spot and darkens. Then it breaks into the dentine, and sensitivity begins. Finally it reaches the pulp, where the pain becomes constant. The table below sums up each stage.

Can a white spot heal?

It can, if you catch it early. While the surface is intact, fluoride toothpaste, a professional fluoride application and less frequent sugar help the enamel harden again. Once the surface collapses into a hole, however, enamel cannot rebuild itself.

What will your dentist do to confirm it?

A dentist dries each tooth and examines it under a bright light. Next, they gently check how firm the surface feels. Bitewing X-rays then show the hidden areas between back teeth. For most people, a check-up is the most reliable answer to how to tell if you have a cavity. It catches decay long before pain does.

Do you need an X-ray?

Not always, but often. Your dentist decides based on your risk and your history of fillings. Bitewings use a low radiation dose and take only seconds.

When does tooth pain mean the decay is deep?

Spontaneous pain, or pain that wakes you at night, suggests decay has reached the pulp. A lingering ache after a cold drink points the same way. At that stage a filling alone is rarely enough. Instead, your dentist will check whether root canal treatment can save the tooth. Swelling or fever, meanwhile, signals an infection that needs prompt care.

Signs that need same-day care

Call a dentist the same day if your face swells or you run a fever. Severe pain that painkillers cannot control needs urgent care too. Go straight to an emergency department if swelling spreads towards your eye or neck. Difficulty swallowing or breathing is an emergency as well.

Can you get rid of a cavity without a dentist?

No. Once a hole forms, only a dentist can remove the softened tissue. Brushing, oil pulling, charcoal or baking soda cannot reach decay inside the tooth. Worse, picking at it with a sharp object can crack enamel and injure the gum. So, until your appointment, the realistic aim is to slow the process down.

What usually fixes a cavity

A small cavity usually needs a simple tooth-coloured filling, often in one visit. Deeper decay may call for an inlay or a crown. If infection has reached the pulp, root canal treatment can often save the tooth; extraction is the last resort. Visitors to Istanbul can have this assessed at our Şişli clinic.

Why does sugar timing matter for your teeth?

Frequency matters as much as quantity when it comes to sugar. Each sugary snack or drink starts an acid attack that lasts a while. Grazing all day keeps teeth under near-constant attack. As a result, saliva never gets time to repair the enamel. Keeping sweet things to mealtimes is a simple fix.

WHO advises keeping free sugars below 10% of total energy intake, and ideally below 5%, to minimise the risk of tooth decay throughout life.

World Health Organization, Sugars and dental caries fact sheet, 2025.

WHO’s 2022 Global Oral Health Status Report named untreated decay the most common health condition worldwide. By its estimate, it affects around 2.5 billion people.

Tooth-friendly food and drink choices

Water is the best everyday drink. Cheese and plain yoghurt encourage saliva and may help neutralise acid. Walnuts and raw vegetables need plenty of chewing, which boosts saliva too. Whole fruit such as apple slices is not free sugar under WHO’s definition, but fruit juice, honey and syrups are. Sugar-free gum after eating helps, but it never replaces brushing.

A routine that keeps cavities away

Brush twice a day with fluoride toothpaste, then spit rather than rinse. Clean between your teeth once a day. After brushing at night, drink only water. For children, fissure sealants protect the back teeth, and our advice on protecting children’s teeth from decay goes into more detail. Finally, keep up regular check-ups.