If you’re feeling a sharp zing when you sip something cold, noticing a dark spot on a tooth, or dealing with pain when you bite down, there’s a good chance you’re dealing with a cavity. About 1 in 5 adults between 20 and 64 has at least one untreated cavity right now, making it one of the most common chronic health problems in the world. The tricky part is that early cavities often have zero symptoms, so by the time you notice something, decay may already be well underway.
What a Cavity Feels Like
The classic cavity sensation is pain that comes and goes, especially when the tooth is exposed to something hot, cold, or sweet. You might notice a brief, sharp twinge when you drink iced water or bite into candy that disappears after a few seconds. As the decay deepens, that sensitivity can linger longer and start showing up when you chew or put pressure on the tooth.
Early-stage cavities, though, feel like nothing at all. Decay starts as invisible mineral loss on the tooth surface before any nerve is involved. That’s why waiting for pain to tell you something is wrong means you’re catching it later than ideal.
What a Cavity Looks Like
You can sometimes spot a cavity yourself, but not always. Here’s what to look for in a mirror with good lighting:
- White spots: A chalky, opaque white patch on a tooth is often the earliest visible sign. It means minerals are leaching out of the enamel, but the surface hasn’t broken down yet. At this stage, the process can sometimes be reversed with fluoride.
- Brown, black, or dark staining: Discoloration on any surface of a tooth, particularly in grooves or between teeth, can signal active decay. Not every dark spot is a cavity (some are just staining from food or drinks), but it’s worth getting checked.
- Visible holes or pits: If you can see or feel an actual hole in a tooth with your tongue, decay has already broken through the enamel surface. This is a cavity that needs treatment.
The problem is that many cavities form between teeth or in spots you simply can’t see. These “hidden” cavities between molars are common and only show up on dental X-rays. That’s a major reason self-diagnosis has real limits: a visual check can catch obvious decay, but it will miss the cavities that are tucked out of sight.
How Cavities Progress
Cavities don’t appear overnight. They develop in stages, and knowing where you are in that progression matters because it determines what kind of treatment you’ll need.
It starts with demineralization. Bacteria in your mouth feed on sugars and produce acid. That acid pulls minerals out of your enamel, making it porous and soft. At first, there’s no hole, just weakened enamel. If the acid exposure keeps happening, a white spot appears on the surface, which is the first thing you might notice visually.
Left alone, tiny cracks (microcavities) form in the porous enamel. Eventually the surface collapses into a full hole. Once decay pushes past the enamel and into the softer layer underneath (dentin), it speeds up. If it reaches the innermost part of the tooth, where the nerve and blood supply live, the pain becomes hard to ignore. At that point, a simple filling won’t fix things anymore.
Cavity Pain vs. Other Tooth Pain
Not every toothache is a cavity. Knowing the difference can save you from panicking or, just as important, from brushing off something serious.
Cavity pain is usually tied to a specific tooth. It flares up with triggers like hot drinks, cold air, sugary foods, or biting pressure, then fades. You might also see redness or swelling in the gum right next to the tooth.
Sinus-related tooth pain affects your upper teeth, since their roots sit close to your sinus cavities. If your tooth pain gets worse when you’re congested or when you bend forward, your sinuses are likely the real issue. This type of pain tends to affect several upper teeth at once rather than just one.
Nerve-related or jaw pain (from things like clenching, grinding, or nerve conditions) tends to be more constant and throbbing. It often isn’t limited to a single tooth, and it can spread across the jaw or the side of your face. The sensation may feel sharp, burning, or electric rather than the dull, trigger-specific ache of a cavity.
Signs a Cavity Has Become Serious
An untreated cavity can eventually become an abscess, which is a pocket of infection at the root of the tooth. This is a different level of problem. Symptoms include a severe, constant, throbbing toothache that radiates into your jaw, neck, or ear. You might develop a fever, notice swelling in your face or cheek, feel tender lumps under your jaw, or taste something foul and salty if the abscess ruptures on its own.
If you have a fever combined with facial swelling, or if you’re having trouble breathing or swallowing, that’s an emergency. The infection can spread into deeper tissues of the jaw, throat, and neck, and in rare cases lead to life-threatening complications like sepsis.
What Happens at the Dentist
A dentist can confirm a cavity in minutes using a visual exam, a thin metal instrument to probe soft spots, and X-rays to reveal decay between teeth or below the surface. There’s no reliable way to get the same certainty at home, which is why a dental visit is the only real answer to “do I have a cavity.”
Treatment depends on how far the decay has gone:
- White spot/early demineralization: Fluoride treatments can help the enamel remineralize and potentially reverse the damage before a hole forms.
- Small to moderate cavity: A filling is the standard fix. The decayed portion is removed and replaced with a filling material. Without insurance, fillings typically cost $200 to $335. With insurance, plans often cover up to 80% of the cost after your deductible.
- Larger cavity with significant structural damage: If too much tooth is gone for a filling to hold but the nerve isn’t involved, an inlay, onlay, or crown may be needed to restore the tooth’s shape and strength.
- Deep decay reaching the nerve: If hot or cold triggers cause intense pain that lingers well after the trigger is gone, the nerve inside the tooth may be damaged. A root canal removes the infected tissue and saves the tooth. In some cases, extraction is the only remaining option.
Why You Can’t Always Tell on Your Own
The biggest cavities are easy to spot. The most common ones aren’t. Decay between teeth, under old fillings, or in the grooves of back molars can be invisible to the naked eye and painless until they’re well advanced. Professional diagnostic tools like X-rays catch these early, when treatment is simpler, cheaper, and less painful. About one in three Americans skip annual dental visits due to cost or anxiety, and that gap between detection and treatment is a big reason untreated decay is so widespread globally.
If you’re noticing any sensitivity, discoloration, or roughness on a tooth that wasn’t there before, those are reasonable signals to get checked. And if you haven’t been to a dentist in over a year, a cavity could be developing without giving you any clues at all.