Cracked Tooth or Cavity? How the Pain Differs

One tooth has started to misbehave. Maybe it zaps you when you bite into toast, then leaves you alone for days. Maybe it aches after a sweet coffee and slowly settles. You want to know what is going on, and whether it can wait.

The two most common reasons for pain in a single tooth are a crack and a cavity. They often feel quite different, and the pattern of your pain is one of the most useful clues a dentist has. They also overlap more than people expect, and only an exam can confirm which one you have, or whether you have both.

First, the Signs That Mean Today

Some symptoms mean the nerve inside the tooth is in trouble or an infection has taken hold, whatever started it. Call a dentist today if you have:

Throbbing pain that starts on its own, keeps you awake, or barely responds to ordinary painkillers
A pimple-like bump on the gum near the tooth, a bad taste, or pus
Swelling of the gum, cheek, or jaw
Pain when you only lightly touch or tap the tooth

Go to a hospital emergency department instead if swelling is spreading into your face, under your jaw, or toward your eye, or if you have a fever, trouble swallowing, or trouble breathing. A spreading dental infection is a medical emergency, and both a crack and a cavity can lead there if left long enough. Our guide to tooth abscess warning signs explains those signs in more depth.

For a structured way to sort out how urgent your symptoms are, our free tooth pain checker screens for emergency signs first and then suggests likely causes. Everything below assumes none of the emergency signs apply.

How Cavity Pain Usually Behaves

A cavity is an area of tooth softened and hollowed out by acid, made by plaque bacteria as they feed on sugar. Early decay usually does not hurt at all. By the time a cavity makes itself felt, it has generally worked through the enamel, the hard outer shell of the tooth, into the dentin, the softer and more sensitive layer underneath.

From there, the typical pattern looks like this:

Sweet things set it off. A twinge or ache shortly after chocolate, soda, or sweetened coffee is one of the more characteristic cavity signs.
Cold, and sometimes heat, trigger it too, usually as a dull ache that fades once the trigger has gone.
It builds gradually. Cavity pain tends to get steadily worse over weeks or months rather than flaring and vanishing.
You can sometimes see or feel it. A dark spot, a chalky white patch, a hole your tongue keeps finding, or a rough edge that shreds floss.
Food packs into the same spot. Decay between two teeth can leave a small ledge where food wedges in at every meal.

If decay reaches the pulp, the nerve and blood vessels in the center of the tooth, the pain changes character. It lingers after hot or cold, begins on its own, and throbs at night. That is usually the point where a filling alone is no longer enough. Our guide to how cavities form and how to stop them covers the earlier, painless stages.

How Crack Pain Usually Behaves

Crack pain is mechanical. The tooth hurts because its pieces flex very slightly when you chew, and that movement irritates the nerve.

A sharp, brief jolt on biting, or on letting go. The classic crack symptom is a quick, electric pain when you bite on something firm, and quite often it comes as you release the bite rather than as you close.
It comes and goes. Days or weeks with no trouble, then a jolt on one particular mouthful. It is hard to reproduce on demand.
It depends on the food and the angle. Seeds, nuts, grainy bread, and chewy foods are common triggers, often only when they land on one exact spot.
It is hard to pin to one tooth. Many people cannot say which tooth it is, or even whether it is upper or lower.
Cold sensitivity with nothing to see. One tooth may react to cold even though it looks perfectly healthy.

Cracks are more common in back teeth, in teeth with large old fillings, in teeth that have had a root canal without a crown, and in people who clench or grind. If a crack reaches the pulp, the pain can become constant like any other inflamed nerve, which is one reason the two problems can end up feeling alike.

Side by Side: Which Symptom Points Where

No single symptom proves anything, but patterns help. Treat this as a guide to what to mention, not a diagnosis.

What you notice	More likely cause	Also worth considering
Sharp jolt when biting something hard or grainy	Crack	A filling that sits too high, an inflamed nerve
Sharp jolt the moment you let go of a bite	Crack	Few other causes produce this so specifically
Ache shortly after something sweet	Cavity	Exposed root surface from gum recession
Brief twinge with cold that fades in seconds	Either, or simple sensitivity	Worn enamel, gum recession
Pain with cold that lingers after the cold is gone	Deep cavity, or a crack reaching the nerve	Irritated nerve after recent dental work
Good days and bad days over several weeks	Crack	Early nerve irritation from decay
Pain that builds steadily week by week	Cavity	A crack that is spreading
Visible hole, dark spot, or rough edge	Cavity	A chipped or broken filling
Food catching in the same place at every meal	Cavity between teeth	Broken filling, gum pocket
You cannot tell which tooth hurts	Crack	Sinus trouble in upper back teeth
Constant throbbing, worse lying down	Advanced nerve problem from either	Abscess

Why Cracks Are So Much Harder to Find

Cavities are comparatively easy to diagnose. A dentist looks, feels the surface with a fine instrument, and takes bitewing x-rays, small side-on images taken while you bite on a tab, which are good at showing decay between teeth.

Cracks are another matter. Fine cracks often do not show on an x-ray at all, either because they are too thin or because they run in the same direction as the beam. A clean x-ray does not rule out a crack. So dentists use other tests:

Bite tests. You bite on a small tool placed on one cusp at a time. The spot that reproduces your jolt points to the tooth, sometimes to the exact corner.
Light. Shining a bright light through the tooth, called transillumination, shows a crack as a line where the light stops.
Dye. A harmless stain brushed onto the tooth soaks into a crack and makes it visible.
Gum measurements. One deep, narrow pocket beside an otherwise healthy tooth can mean a crack runs down the root.
Looking under an old filling, which often reveals a crack across the floor of the tooth.

It can genuinely take more than one visit to find a crack.

The Range of Cracks, From Craze Lines to a Split Tooth

"Cracked tooth" covers several different things:

Craze lines are tiny lines in the enamel only. Most adults have some. They are painless and need no treatment.
A fractured cusp is a corner of a back tooth breaking away, often beside a large filling.
A cracked tooth has a crack running from the chewing surface down toward the root. This is the one with the classic come-and-go bite pain, and catching it early matters because it can spread.
A split tooth has cracked all the way through into separate pieces. It usually cannot be saved whole.
A vertical root fracture starts in the root and works upward, often showing only as a gum infection, most commonly in a tooth that has had a root canal.

If a piece has actually broken off, our guide on a cracked or chipped tooth covers what to do before your appointment.

Can You Have Both?

Yes, and it is common. A crack gives bacteria a route into the tooth, so decay can start along the crack line. A large filling placed years ago for decay leaves thin walls that are prone to cracking. And once either problem reaches the pulp, the pain looks much the same: lingering, spontaneous, and worse at night.

Why the Difference Matters for Treatment

A cavity caught while it is still in the enamel or dentin is usually fixed with a filling, where the decay is removed and the space rebuilt with tooth-colored material. A small filling typically runs about $150 to $400, and a larger one on a molar about $250 to $600. Decay that has undermined the tooth may need a crown, and decay that reaches the nerve needs a root canal.

A crack is different, because a filling does not hold a cracked tooth together. The usual aim is to brace the tooth so the pieces can no longer flex, which means a crown, roughly $1,000 to $2,500 depending on the material, or sometimes an onlay, a partial crown covering only the cusps. If the crack has inflamed the pulp, a root canal comes first, typically $700 to $1,300 for a front tooth, $800 to $1,500 for a premolar, and $1,000 to $2,000 for a molar. A split tooth or a root fracture usually means removal.

These are ranges, not quotes. Where you live, the material chosen, and how complicated your tooth is all move the price, and insurance changes what you actually pay.

The practical point: an early crown on a cracked tooth often saves a tooth that would be lost if the crack were left to grow.

How to Describe Your Pain at the Appointment

The detail you bring can shorten the search. Notice whether the pain comes as you bite down or as you release, which foods set it off, whether sweets trigger it, whether cold pain fades or lingers, and whether it ever hurts with no trigger at all.

Frequently Asked Questions

Can a cavity feel like a cracked tooth?

Yes. A deep cavity can weaken a cusp so that it flexes when you bite, and a cavity that has reached the nerve can make the tooth tender to chew on. The difference is usually in the background pattern: cavity pain tends to build steadily and react to sweets, while crack pain comes and goes and depends on how you bite.

Why didn't my crack show up on the x-ray?

Fine cracks are often invisible on standard dental x-rays, especially when they run in the same direction as the beam. That is why dentists use bite tests, light, and dye as well. A normal x-ray means no obvious decay or infection was seen, not that the tooth is definitely uncracked.

My tooth only hurts once in a while. Can it wait?

It can usually wait days rather than hours if you have none of the urgent signs listed near the top. It should not wait months. An intermittent crack can quietly spread, and a cavity keeps growing whether or not it hurts today.

Does a cracked tooth always need a crown?

No. Craze lines need nothing, and a small fractured cusp can sometimes be repaired with a filling or an onlay. A true crack running toward the root usually does need a crown to stop it spreading. Your dentist will decide based on where the crack is and how much healthy tooth is left.

Can a cavity or a crack go away on its own?

A crack never heals, because enamel has no living cells to knit it back together. Very early decay, still only in the enamel, can sometimes be halted with fluoride and better habits, but a cavity that has formed a hole cannot. If the pain stops by itself, that can mean the nerve has died, which is not good news.

What to Do Next

Check the urgent list first. Swelling, fever, trouble swallowing, or constant throbbing pain means you should be seen today, or at a hospital if the swelling is spreading.

If none of that applies, book an exam within the next week or two. Keep a short note of what triggers the pain and whether it comes on biting, on release, or after sweets, and take it with you. In the meantime, chew on the other side, and do not wait for it to go away by itself, because neither a crack nor a cavity will.