Teeth rarely break without warning. A crack can produce symptoms for weeks or months that are easy to overlook, because they are brief, they seem to change location, and they disappear for days at a time. In retrospect, after a piece comes off, the pattern is often recognizable.

This is general information about a common problem. Whether your own tooth has a crack is something an examination can answer, and we’re glad to take a look.

Pain on release of a bite

One characteristic symptom is pain on release. Biting down on something firm, such as a nut or a piece of bread crust, produces nothing. Releasing the bite produces a sharp jolt that lasts a fraction of a second.

That happens because a crack lets the segments of the tooth flex apart slightly under load. Fluid moves inside the microscopic tubules of the dentin beneath the enamel, and the nerve registers that movement as a brief, sharp pain. When the pressure comes off, the segments settle back together and the fluid moves again. Other problems can cause pain on chewing as well, so this pattern on its own does not confirm a crack. It should still be reported at a visit, including the detail that the pain comes on release rather than on the bite, because that detail helps narrow the search.

Other patterns that can point toward a crack:

Sharp, short cold sensitivity on one tooth. A cold drink produces a sharp response that stops within a second or two. Sensitivity that lingers and throbs after the cold is gone is a different signal and points more toward nerve inflammation.
Pain that is difficult to localize. The pain may seem to sit somewhere on the upper left, or to come from a different tooth on different days. The nerves that supply teeth converge, and pain from a single tooth is genuinely difficult to localize.
Symptoms that come and go. Weeks without symptoms can be followed by several painful days. That intermittent pattern is common with cracks, and it is part of why a crack can go a long time before it is examined.
Pain with certain foods only. Chewy bread, popcorn, ice and granola are common triggers. A crack often requires a specific direction of force to open.

Why cracks are hard to find

An x-ray shows density. A crack is a thin gap, and unless the beam happens to pass along the plane of that gap, the image can look normal. Real cracks are often invisible on a technically good x-ray, so a normal image does not rule one out.

Finding a crack is therefore mostly a clinical process. It generally involves biting tests on one cusp at a time to see which one reproduces the pain on release, testing how the tooth responds to cold, and a close look at the tooth and at the margins of any existing filling. Sometimes the line only becomes visible once an old filling is removed and the floor underneath can be seen. A first visit does not always settle the question, and when it does not, the next step is to track which foods trigger the pain and return with that information.

Where cracks come from

Large older fillings are a common setting. A filling fills a space in a tooth rather than reinforcing it, and a tooth with a wide filling has thin walls of enamel left standing on either side. Thin walls flex more under load than thick ones do, and years of ordinary chewing on them can be enough.

Clenching and grinding, especially at night, load teeth for far longer than eating does. Waking with a tight jaw or sore temples, or having teeth with flattened, polished wear facets, can be a sign that teeth are carrying load for hours rather than minutes.

A single event can also be responsible: an olive pit, an unpopped popcorn kernel, ice, a fork, a fall. Teeth that have had root canal treatment also break more often, mostly because they usually had extensive decay or a large filling first and have less structure left, which is why a crown is often recommended after root canal therapy.

Types of cracks

The word crack covers a range of conditions, from shallow lines that need no treatment at all to fractures that mean a tooth cannot be kept.

Craze lines are shallow lines in the enamel only. They are common in adults, they cause no pain, and they require no treatment.

A fractured cusp is a piece of the chewing surface that separates, often next to a filling. The piece comes off, the pain usually stops, and the tooth is restored.

A cracked tooth runs from the chewing surface toward the root and is still in one piece. This is the type that tends to produce pain on release. Treated early, the tooth often does well; without treatment, the crack can extend.

A split tooth is a cracked tooth that has separated into segments. Whether any part of it can be kept depends on where the split runs.

A vertical root fracture starts in the root and often appears first as a gum problem near one spot on the tooth. These usually end in extraction.

There is a real limit to what can be known in advance, because no one can see how deep a crack runs before treatment starts. A tooth can be crowned and settle down completely. It can still need root canal treatment afterward because the nerve was already irritated. It can turn out to be split once the old filling is out. What you should receive is a clear explanation of the likely outcome, the alternatives, and the plan if the first treatment does not succeed.

What can happen if a crack is left alone

Cracks do not heal, and the direction a crack travels makes most of the difference. A crack that stays above the gum line usually ends with a restoration. The same crack, once it extends below the bone level, usually ends with an extraction and a discussion about replacing the tooth. There is no reliable way to predict how long that takes.

Meanwhile the flexing continues to irritate the nerve, and a tooth that was painful only on release can progress to aching on its own and need root canal therapy along with a crown.

What to do in the meantime

Chew on the other side, and avoid hard and chewy foods on that tooth. Avoid testing the tooth, since biting down repeatedly to check for pain loads the crack each time. If you clench or grind, mention it at the appointment, because a night guard can protect a repair along with the rest of your teeth.

Call sooner rather than waiting for a routine visit if you have swelling of the face or gum, a fever, pain that wakes you or does not respond to what you would normally take, a sharp edge cutting your tongue or cheek, or a piece of tooth that has come out. Our dental emergencies page covers what to do first. For anything involving difficulty breathing or swallowing, or swelling that is spreading toward the eye or down the neck, call 911 rather than the office.

If a tooth has been producing the symptoms described here, the next step is an examination. Call (559) 683-4694 or request an appointment, and bring the details with you: which tooth, which foods, and whether the pain comes on the bite or on the release. That history often narrows the search faster than anything else. You can read more about the range of repairs on our restorative dentistry page.

What a Cracked Tooth Feels Like Before It Breaks