A cracked tooth allows bacteria to seep into the inner layers of the tooth, triggering pain, sensitivity, and potentially serious infection if left untreated. What happens next depends entirely on how deep the crack goes and how quickly you get treatment. Some cracks are harmless surface lines that never cause problems. Others can progress to the point where the tooth splits apart or develops an abscess within weeks to months.
Not All Cracks Are the Same
Tooth cracks fall along a spectrum from cosmetically minor to structurally devastating, and the type you have determines everything about your prognosis.
Craze lines are the most common and least concerning. These tiny surface cracks affect only the outer enamel, cause no pain, and don’t need treatment. Nearly every adult has them.
Fractured cusps happen when a piece of the chewing surface breaks off, often around an existing filling. Because the break rarely reaches the inner pulp of the tooth, pain is usually minimal and the fix is straightforward.
A true cracked tooth is more serious. The crack runs vertically from the chewing surface down toward the root. The tooth hasn’t separated into pieces yet, but the crack can gradually deepen over time. This is the type most people are dealing with when they search for answers.
Split teeth represent the end stage of a cracked tooth that was never treated. The crack has progressed until the tooth separates into distinct segments. A split tooth cannot be saved intact.
Vertical root fractures start at the root and work upward. They’re sneaky because they often produce minimal symptoms and go unnoticed until the surrounding bone and gum tissue become infected. These fractures frequently require extraction.
What You’ll Feel
The hallmark symptom of a cracked tooth is sharp, erratic pain when biting down, especially when you release the bite. Unlike a cavity, which tends to produce a constant ache, cracked tooth pain comes and goes unpredictably. You might chew on one side for days without a problem, then hit the tooth at just the wrong angle and feel a jolt.
Sensitivity to hot and cold is common, particularly to cold drinks or air. Sweet foods can also trigger discomfort. The pain often makes it hard to pinpoint which tooth is the problem because it can radiate along the jaw. Some people go weeks assuming they have a sinus issue or a different tooth entirely before the crack is identified.
How a Crack Damages the Tooth From Inside
The outer enamel of your tooth is a sealed barrier. Once a crack breaches it, bacteria from your mouth gain a direct path to the soft tissue inside the tooth, called the pulp. The pulp contains nerves and blood vessels, which is why a cracked tooth hurts in ways a surface chip doesn’t.
Initially, the pulp becomes inflamed but can still recover if the tooth is treated. This reversible stage doesn’t last long. In a study tracking 127 patients with early-stage pulp inflammation from cracked teeth, about one in five progressed to irreversible damage in roughly two months. Some developed a completely dead (necrotic) pulp within five months. Once the pulp dies, the tooth becomes a harbor for bacterial growth, setting the stage for infection.
What Happens if You Don’t Treat It
Ignoring a cracked tooth doesn’t just risk losing the tooth. Bacteria that reach the root tip can form an abscess, a pocket of infection that causes swelling, throbbing pain, and sometimes fever. From there, the infection can spread into the jawbone and surrounding tissues.
For upper teeth located near the sinus cavities, an abscess can create an opening between the tooth and the sinus, leading to a sinus infection. In rare but serious cases, an untreated dental abscess can spread to the head and neck or enter the bloodstream, causing sepsis. These outcomes are uncommon with modern dental care, but they illustrate why a cracked tooth isn’t something to put off indefinitely.
Why Cracks Are Hard to Diagnose
One of the most frustrating aspects of a cracked tooth is that standard dental X-rays often can’t detect the crack. Cracks run vertically, while X-ray beams pass through the tooth horizontally, making fine fracture lines essentially invisible on film.
Dentists rely on a combination of hands-on tests instead. A bite test, where you bite down on a small stick or cushion placed on individual cusps, reproduces the sharp pain when pressure hits the cracked segment. Transillumination, which involves shining a bright light through the tooth, reveals cracks because light scatters at the fracture line instead of passing through evenly. Both methods are effective. In clinical evaluations, all teeth with cracked tooth symptoms tested positive on both the bite test and transillumination.
Your dentist may also use a dental explorer to feel for the crack line or apply dye that seeps into and highlights the fracture. Sometimes a crack only becomes visible after an old filling is removed.
Treatment Options and What to Expect
Treatment depends on how far the crack extends and whether the pulp is involved.
- Crown: If the crack hasn’t reached the pulp, placing a crown over the tooth can hold it together and prevent the crack from spreading. This is the most common treatment for a cracked tooth caught early.
- Root canal plus crown: If bacteria have already damaged the pulp, the infected tissue needs to be removed through a root canal before a crown is placed. This combination is the standard approach for cracked teeth with significant symptoms.
- Extraction: If the crack extends below the gum line or the tooth has split into segments, saving it usually isn’t possible. The tooth is removed and can be replaced with an implant or bridge.
Long-Term Survival Rates
Even with root canal treatment and a crown, a cracked tooth has a limited lifespan compared to an intact tooth. A retrospective study following cracked teeth for up to 15 years found a 66% survival rate at 10 years and 55% at 15 years. That means roughly one in three treated teeth will eventually be lost within a decade.
The single biggest predictor of whether a cracked tooth will last is the health of the gum and bone around it at the time of treatment. Teeth with healthy gum pockets (less than 4 millimeters deep) had a much better outlook: 76% survival at 10 years and 64% at 15 years. Teeth with deeper gum pockets, a sign that the crack or infection had already affected surrounding structures, faced two to three times the risk of failure. This is one of the clearest arguments for treating a cracked tooth sooner rather than later.
Common Causes and Prevention
Teeth crack for a handful of predictable reasons. Biting down on something unexpectedly hard, like an unpopped popcorn kernel, olive pit, or ice cube, is a classic trigger. Large existing fillings weaken the surrounding tooth structure and make cracks more likely. Age plays a role too, with most cracked teeth occurring in people over 40 as enamel gradually becomes more brittle.
Grinding or clenching your teeth, especially during sleep, is one of the most significant risk factors. The repeated lateral forces placed on teeth during bruxism far exceed normal chewing pressure and can initiate or worsen cracks over time. If you grind, a custom night guard from your dentist creates a buffer that absorbs and distributes those forces. Over-the-counter versions offer some protection but fit less precisely.
For athletes, a sports mouthguard significantly reduces the risk of chipped, cracked, and knocked-out teeth during contact sports and high-fall-risk activities like biking or gymnastics. Avoiding chewing on ice, pen caps, and other hard objects removes another common source of fracture force.