A tooth dies when the soft tissue inside it, called the pulp, loses its blood supply and the cells break down. This can happen from untreated decay, a crack, or a blow to the face. The process can take weeks to years depending on the cause, and sometimes you won’t feel any pain at all until the damage is done.
What’s Inside a Living Tooth
Underneath the hard white enamel you can see, every tooth contains a chamber of living tissue. This pulp holds blood vessels, nerves, and cells that nourish the tooth from the inside. Blood enters through a tiny opening at the tip of each root, and that’s the only way in. This single entry point is a design flaw that matters: unlike most tissues in your body, the pulp can’t easily reroute blood flow or recruit new vessels when something goes wrong.
How the Pulp Dies
When bacteria from a cavity or a crack reach the pulp, or when a hard impact damages the tissue, the body responds with inflammation. Normally, swelling is a helpful part of healing. But the pulp is trapped inside a rigid shell of dentin and enamel with no room to expand. The pressure builds, squeezing the blood vessels shut. Because no backup blood supply can form through that single root opening, the tissue starves and dies.
This process happens in stages. First comes reversible pulpitis, where the inflammation is mild enough that the tooth can still recover if a dentist treats the problem. If nothing is done, it progresses to irreversible pulpitis, where the damage is too far gone for the pulp to heal. The final stage is full necrosis: the tissue is dead, and the tooth is no longer alive.
Tooth Decay Is the Most Common Cause
The majority of dead teeth start with an ordinary cavity. A small area of decay on the surface is painless and easy to fix. But bacteria keep eating inward through the enamel, then through the softer dentin layer beneath it. Once they reach the pulp chamber, infection triggers the inflammatory chain reaction described above. This progression can take months or years, which is why regular dental visits catch problems before they reach the pulp.
A cracked or chipped tooth works the same way. Even a hairline fracture you can’t see gives bacteria a shortcut past the enamel. Grinding your teeth at night, biting down on something hard, or old fillings that weaken the tooth structure can all create these entry points.
Trauma Can Kill a Tooth Without Decay
A blow to the mouth from a fall, a car accident, or a sports injury can damage the pulp’s blood supply directly, even if the tooth looks perfectly fine on the outside. The impact either tears or compresses the blood vessels entering through the root tip, cutting off circulation.
Research tracking outcomes after dental injuries found that even relatively minor trauma causes pulp death more often than most people expect. After a concussion injury (the tooth is sore but didn’t move), about 16% of teeth eventually lost vitality. After a subluxation (the tooth loosened but stayed in its socket), that number rose to 27%. Most of these cases showed up within six months of the injury. More severe injuries, where a tooth is pushed into the gum or knocked completely out, carry even higher rates.
If a tooth gets knocked out entirely, the clock starts immediately. Replanting it within five minutes gives the best chance of survival. If you can’t do that right away, storing the tooth in cold milk is the best practical option. Keeping it in your mouth (tucked between your cheek and gum) works as a backup. Letting it dry out is the worst scenario. After 20 minutes of dry time, the risk of the root fusing to the bone rises sharply, and after 60 minutes, the cells on the root surface are unlikely to survive at all.
Signs of a Dead Tooth
A dead tooth doesn’t always announce itself with pain. In fact, once the nerve tissue dies completely, you may lose all sensitivity to hot, cold, and sweet foods in that tooth. The absence of sensation that was previously there is itself a warning sign.
The most visible clue is discoloration. A dead tooth gradually turns gray, dark yellow, or brown as the blood cells inside break down. After trauma, this color change typically becomes noticeable within weeks to a few months. With slow-moving decay, the darkening may take longer to appear or may be hidden beneath a filling.
Other signs depend on the stage. During irreversible pulpitis (before the pulp fully dies), you might feel throbbing or aching pain, lingering sensitivity to temperature that lasts more than a few seconds, or pain that wakes you up at night. Once the pulp is dead, the pain pattern shifts. The tooth itself may feel numb, but if infection spreads beyond the root tip, you can develop a dull, deep ache in the jaw, swelling in the gum, or a small pimple-like bump on the gum near the tooth’s root. That bump is a drainage point for a periapical abscess forming at the root tip.
What Happens If You Leave It
A dead tooth doesn’t simply sit quietly in your jaw. The necrotic tissue inside becomes a breeding ground for bacteria, and without a blood supply, your immune system can’t reach the infection. Over time, bacteria multiply and spread beyond the root tip into the surrounding bone, forming an abscess.
A periapical abscess can erode the jawbone around the tooth, damage neighboring teeth, and spread to other areas. If the infected tooth is in the upper jaw, the infection can reach the sinus cavity behind your nose. In rare but serious cases, it can spread along tissue planes into the neck or enter the bloodstream. These complications are preventable with treatment but can become life-threatening if ignored for too long.
How a Dead Tooth Is Identified
Dentists test whether a tooth is alive by checking if its pulp responds to stimulation. The most common in-office method is a cold test: a chilled instrument is placed against the tooth, and a living pulp will produce a brief, sharp sensation. A dead tooth feels nothing. Electric pulp testing sends a small current through the tooth to provoke a nerve response. Cold testing correctly identifies a dead tooth about 87% of the time, while electric testing is better at confirming a tooth is alive (93% accuracy) but less reliable at catching dead ones (72%).
X-rays help complete the picture. They can reveal dark areas at the root tip where bone has been destroyed by infection, widening of the space around the root, or deep decay reaching the pulp chamber. In ambiguous cases, more advanced tools that measure actual blood flow through the tooth are the most accurate, with diagnostic precision around 97%.
How Dead Teeth Are Treated
Once the pulp is dead, it cannot regenerate. Treatment focuses on removing the dead tissue and saving the outer structure of the tooth whenever possible. A root canal is the standard approach: the dentist clears out the necrotic pulp, disinfects the internal canals, and fills them with an inert material. The tooth is then sealed, usually with a crown, to prevent future cracking. After a root canal, the tooth stays in your mouth and functions normally for chewing, though it’s more brittle over time since it no longer receives internal nourishment.
If the tooth is too damaged to restore, or if the infection has caused severe bone loss around the root, extraction is the alternative. The gap can then be addressed with an implant, bridge, or other replacement.
Preventing a Tooth From Dying
Most dead teeth are preventable. Treating cavities while they’re still in the enamel keeps bacteria far from the pulp. If you crack or chip a tooth, getting it repaired quickly seals off the pathway bacteria would use to reach the interior.
For physical activity, a properly fitted mouthguard absorbs impact energy and dramatically reduces the risk of pulp damage from trauma. This matters for contact sports, but also for activities like mountain biking, skateboarding, or basketball where falls and collisions happen.
If you grind your teeth at night, a night guard reduces the cumulative stress that weakens tooth structure and creates microcracks. And if you notice lingering sensitivity to hot or cold that wasn’t there before, that’s often the reversible pulpitis stage, the window where early treatment can still save the pulp.