How to Know If You Have a Cavity

Sensitivity to sweets:

One of the earliest and most reliable signs of a cavity is sensitivity when eating sweet foods or drinking sugary beverages. This happens because sugar draws fluid from inside the tooth, stimulating the nerve. If one particular tooth consistently hurts when you eat candy, drink soda, or have other sweet items, that's a red flag worth investigating.

Temperature sensitivity:

Sensitivity to hot or cold that lingers is another common cavity sign. Healthy teeth may briefly feel cold when you eat ice cream, but the sensation passes quickly. If discomfort lasts more than a few seconds after the hot or cold stimulus is removed, it may indicate that decay has progressed enough to affect the dentin layer beneath the enamel, which is more connected to the nerve.

Visible changes to your teeth:

Sometimes you can actually see a cavity. Look for dark brown or black spots on the tooth surface (though not all dark spots are cavities—some are staining). Visible holes or pits in the tooth surface are more definitive signs. White spots on the enamel can indicate early demineralization—the first stage of decay—which may be reversible with good care.

Pain when biting:

If a tooth hurts specifically when you bite down on it, this could indicate decay has weakened the tooth structure, causing flexion that irritates the nerve. It could also suggest a crack or other problem.

Other clues:

Food frequently getting stuck in the same spot may indicate a cavity has created a trap for food particles. Floss that shreds or catches on a particular tooth might be snagging on a rough cavity edge. A rough spot or sharp edge you can feel with your tongue where there wasn't one before could be a cavity breaking down the tooth surface.

Cavities often start where you can't see:

Up to 40% of tooth surface area is between teeth—invisible to your eyes no matter how wide you open your mouth. Interproximal cavities (between teeth) are extremely common and can grow quite large before causing any symptoms. You could have a significant cavity that you'd never know about without an X-ray.

Pain comes late in the game:

Tooth enamel has no nerve endings, so early decay in the enamel causes no pain whatsoever. By the time a cavity hurts, it has typically progressed through the enamel, through much of the dentin, and is approaching or reaching the pulp (nerve). This is why "it doesn't hurt" is not evidence that you don't have a cavity.

Hidden decay:

Cavities can develop under existing fillings, beneath crowns, or at the margins where restorations meet natural tooth structure. These can't be seen visually and may not cause symptoms until they become advanced.

Why professional checkups matter:

Dentists have tools you don't have at home. X-rays (radiographs) reveal cavities between teeth and under fillings that are invisible to the naked eye. Explorer probes can detect soft spots in enamel that feel normal to the tongue. Some dentists use additional technology like laser cavity detectors, which can identify early decay before it's visible on X-rays.

Regular checkups—typically every six months—catch cavities when they're small. A tiny cavity caught early needs a small filling costing $150-$300. That same cavity, given another year to grow, might need a large filling, a crown, or even a root canal costing $1,000-$2,500 or more.

Schedule a dental appointment:

Don't wait. Cavities only grow larger with time, never smaller. A cavity that might need a simple filling today could need a root canal in six months. Call your dentist and explain your symptoms; many offices will work you in quickly for potential cavities.

If you don't have a regular dentist, look for one who accepts your insurance (if you have it), or search for community health centers or dental schools that offer reduced-cost care.

While you're waiting for your appointment:

Continue your normal oral hygiene routine—brush twice daily with fluoride toothpaste and floss daily. Good hygiene won't fix an existing cavity, but it prevents existing decay from progressing as quickly and prevents new cavities from developing.

If you're experiencing sensitivity, avoid very hot, very cold, or very sweet foods that trigger discomfort. This isn't treating the problem; it's just managing symptoms while you wait for professional care.

Over-the-counter pain relievers like ibuprofen or acetaminophen can help if you're having pain, but treat this as a temporary measure, not a solution. Pain that requires regular medication needs professional attention.

Don't try home treatments:

Despite what you might read online, you cannot heal a cavity at home. Oil pulling, special toothpastes, and supplements will not reverse decay once it has broken through the enamel surface. Very early demineralization (white spots before actual cavities form) can sometimes be remineralized with fluoride, but actual cavities need professional treatment.

The examination:

Your dentist will visually examine your teeth, looking for visible signs of decay. They'll use a small instrument called an explorer to probe suspicious areas—soft spots indicate decay. They'll likely take X-rays if you haven't had recent ones, which reveal cavities between teeth and under existing work.

If you have a cavity:

Your dentist will explain where the cavity is, how large it is, and what treatment they recommend. For small to moderate cavities, this is typically a filling—removing the decay and filling the space with composite resin, amalgam, or another material. Larger cavities might need a crown. Decay that reaches the nerve requires a root canal.

If you don't have a cavity:

That sensitivity might be from other causes: gum recession exposing the root surface, a cracked tooth, teeth grinding, or simple sensitivity that some people naturally have. Your dentist can help identify the cause and recommend treatment.