A fractured tooth is any crack or break in a tooth’s structure, ranging from a painless hairline in the enamel to a deep split that reaches the root. Not all fractures are equal: some need no treatment at all, while others can lead to infection and tooth loss if ignored. The type, depth, and location of the fracture determine how serious it is and what comes next.
Five Types of Tooth Fractures
The American Association of Endodontists classifies tooth fractures into five categories, each with a different outlook.
Craze lines are the most common and least serious. These are tiny, hairline cracks confined entirely to the outer enamel, usually appearing as faint vertical lines on the tooth surface. They don’t reach the gums or the deeper layers of the tooth, they cause no pain, and they need no treatment. Nearly every adult has them. They only become a concern if they deepen over time into the layer beneath the enamel.
Fractured cusps involve a break in one of the raised points on the chewing surface, often on a tooth that already has a large filling. You’ll typically feel a sharp pain when chewing and sensitivity to cold. The prognosis is very good: your dentist removes the broken piece and restores the tooth, often with a crown or onlay.
Cracked teeth have a fracture line that runs from the chewing surface down toward the root, sometimes reaching below the gum line. Symptoms are highly variable. Some people feel intermittent sharp pain when biting; others notice sensitivity to cold or sweet foods that comes and goes. Because the crack can allow bacteria into the tooth’s inner tissue, root canal treatment is often necessary, followed by a crown to hold the tooth together. The long-term outlook for cracked teeth is always uncertain.
Split teeth are what happens when a cracked tooth goes untreated long enough for the crack to progress all the way through. The tooth separates into distinct segments. At that point, at least one segment has to be removed. Depending on the extent of the split, the remaining portion may be restorable, or the entire tooth may need extraction.
Vertical root fractures start in the root rather than the chewing surface and work their way upward. They often produce minimal symptoms, which makes them notoriously difficult to diagnose. These fractures frequently occur in teeth that have already had root canal treatment. If left undetected, a vertical root fracture can cause extensive bone loss around the root, potentially compromising the site for a future dental implant. Most vertically fractured roots ultimately require extraction.
What Causes Teeth to Fracture
Teeth fracture when the forces acting on them exceed their structural strength. Several factors tip that balance.
Large fillings are one of the most common culprits. Once a filling becomes too wide or too deep, the remaining tooth walls thin out and lose structural integrity. The cusps become undermined, and normal biting forces from opposing teeth can crack them over time. Teeth with old, extensive amalgam fillings are especially vulnerable because the metal doesn’t bond to the tooth the way newer materials do.
Grinding and clenching (bruxism) places repetitive, excessive force on teeth, often during sleep when you can’t consciously limit the pressure. People with a heavy bite are simply harder on their teeth and more likely to develop cracks over the years. Chewing on ice, hard candy, or unpopped popcorn kernels creates sudden, concentrated force that can fracture even healthy enamel. Thermal cycling, the repeated expansion and contraction from alternating hot and cold foods, contributes to craze lines over time. Trauma from sports injuries, falls, or accidents can fracture any tooth instantly, regardless of its prior condition.
How a Fractured Tooth Feels
The hallmark symptom is sharp, brief pain when you bite down on something, particularly on the release of the bite rather than the initial contact. This happens because chewing forces momentarily open the crack, irritating the nerve-rich tissue inside, and releasing the bite lets the crack snap back together. The pain is often inconsistent: it might happen with one bite and not the next, depending on exactly where the food hits.
Sensitivity to cold is the other classic sign. Sweet foods can also trigger discomfort. Unlike a cavity, which tends to produce steady, predictable pain, a cracked tooth often causes symptoms that seem random and hard to pin down. Some fractures, particularly vertical root fractures and early-stage cracks, produce little or no pain at all, which is part of what makes them dangerous.
How Dentists Find the Fracture
Cracks in teeth can be surprisingly difficult to locate. They don’t always show up on standard X-rays, and the symptoms can mimic other dental problems. Dentists rely on a combination of tools and tests to confirm the diagnosis.
Transillumination is the most informative method. Your dentist shines a bright, focused light through the tooth. Light travels through intact tooth structure but stops at a crack, creating a visible dark line where the fracture interrupts the beam. The room lights and dental lamp are turned off so only the transilluminator’s beam is visible, and a dental mirror is used to examine the tooth from multiple angles. A surgical operating microscope can add magnification for subtle cracks.
Bite tests use a small instrument placed on individual cusps while you bite down, isolating exactly which part of the tooth reproduces the pain. Dye staining involves painting a colored solution onto the tooth surface; the dye seeps into crack lines and makes them visible. Periodontal probing checks for narrow, isolated pockets of gum detachment along the tooth, which can signal a crack extending below the gum line. For vertical root fractures, a characteristic J-shaped pattern of bone loss on X-rays, extending from the root tip up to the gum line, is a strong diagnostic clue.
Treatment Based on Fracture Depth
How deep the fracture reaches determines the treatment. A tooth has three main layers: the hard outer enamel, a softer layer called dentin beneath it, and the pulp at the center, which contains nerves and blood vessels.
Fractures limited to enamel (craze lines) need nothing beyond cosmetic improvement if the appearance bothers you. Fractures that extend into dentin but don’t reach the pulp can often be repaired with composite bonding, a tooth-colored resin applied in a single visit. This works well for minor chips and fractured cusps where enough healthy tooth structure remains to support the repair.
When a fracture reaches the pulp, bacteria from the mouth gain direct access to the nerve and blood supply inside the tooth. At that point, the size of the exposure matters. A small exposure of healthy pulp tissue has a better chance of being preserved, while a larger exposure or one where the pulp tissue has already lost its blood supply typically requires root canal treatment. After a root canal, the tooth loses its internal blood supply and becomes more brittle, so it almost always needs a full-coverage crown for long-term protection.
For split teeth and vertical root fractures, the options narrow considerably. A split tooth may be partially salvageable if one segment can be removed and the remaining structure is sound enough to restore. Vertical root fractures generally require extraction of the affected root or the entire tooth.
Long-Term Survival of Treated Cracked Teeth
A 10- to 15-year study of 204 cracked teeth treated with root canals found a 66% survival rate at 10 years and 55% at 15 years. Those numbers improve significantly when the tooth starts in better condition. Teeth with healthy gum attachment at the time of treatment survived at a rate of 76% at 10 years and 64% at 15 years, comparable to teeth that were never cracked. Teeth that already had deep gum pockets before treatment faced two to three times the risk of failure.
Older age was a modest independent risk factor, with each additional year of age slightly increasing the chance of eventual tooth loss. These findings suggest that catching and treating a crack early, before gum and bone damage set in, gives you the best shot at keeping the tooth long-term.
What Happens if You Ignore It
A crack in your tooth is an open door for bacteria. Once bacteria reach the pulp through a fracture line, they trigger inflammation called pulpitis. In its early, reversible stage, pulpitis causes heightened sensitivity that fades after the stimulus is removed. If the infection progresses, the inflammation becomes irreversible, the pulp tissue dies, and the tooth can no longer heal on its own.
Dead pulp tissue doesn’t just sit quietly. It becomes a breeding ground for infection that can spread beyond the tooth into the surrounding bone, forming an abscess. Symptoms escalate to constant pain, fever, and swollen glands in the neck. In rare but serious cases, the infection can spread to the jawbone or the soft tissues of the head, neck, and chest. These spreading infections can become life-threatening without treatment.
The progression from a small crack to a serious infection isn’t inevitable, and it doesn’t happen overnight. But it does happen, and the earlier a fracture is identified and addressed, the simpler and more predictable the treatment.