Pulpitis is inflammation of the soft tissue inside your tooth, called the pulp. This tissue contains nerves and blood vessels, which is why pulpitis often causes intense, hard-to-ignore pain. It’s one of the most common reasons people end up in an emergency room for a dental problem. In 2018, diseases of the pulp accounted for about 85% of dental-related ER visits that led to hospital admission.
What Happens Inside the Tooth
Your tooth’s outer layers, enamel and dentin, normally shield the pulp from the outside world. When that barrier breaks down through a cavity, crack, or other damage, bacteria can reach the pulp and trigger an immune response. Blood vessels in the pulp widen to increase blood flow, and the walls of tiny veins become more permeable so immune cells can flood into the area.
Here’s the problem: the pulp sits inside a rigid chamber with almost no room to expand. As blood flow increases and fluid accumulates, pressure builds in that confined space. This swelling compresses the veins and lymphatic vessels that would normally drain excess fluid, creating a vicious cycle that can starve the tissue of oxygen and eventually kill it. That buildup of pressure on the nerve fibers is also why pulpitis pain can feel so severe.
Common Causes
The most frequent cause is a cavity that has grown deep enough to reach or get close to the pulp. Bacteria in your mouth produce acid that gradually dissolves enamel, and once they penetrate through to the inner tissue, infection sets in. Cracks from biting down on hard foods or from an injury to the mouth can also open a path for bacteria.
Dental procedures themselves sometimes cause pulpitis. The heat and vibration from drilling, or chemical irritation from bonding materials, can inflame the pulp. If a filling doesn’t seal properly, bacteria can leak underneath it over time. Repeated work on the same tooth raises the cumulative risk. Less commonly, heavy bite forces or orthodontic tooth movement can irritate the pulp enough to cause inflammation.
Reversible vs. Irreversible Pulpitis
Dentists classify pulpitis into two types based on whether the pulp can recover.
Reversible Pulpitis
With reversible pulpitis, the inflammation is mild enough that the pulp can heal once the irritant is removed. The hallmark symptom is a sharp, quick pain when your tooth is exposed to something cold, sweet, or acidic. The pain comes on fast and stops within a few seconds once the trigger is gone. You can usually point to exactly which tooth hurts. At this stage, the nerve fibers closer to the surface of the pulp are reacting, but the deeper tissue hasn’t been seriously damaged.
Irreversible Pulpitis
In irreversible pulpitis, the inflammation has progressed to the point where the pulp can’t recover on its own. Pain tends to linger well after a trigger is removed, sometimes lasting minutes or longer. Heat often makes it worse, and the pain may be harder to pinpoint. A key difference is spontaneous pain, meaning your tooth throbs or aches without any obvious trigger, sometimes waking you up at night. The deeper, slower nerve fibers in the pulp are now involved, producing a dull, radiating ache rather than a sharp sting.
One important caveat: pain intensity alone doesn’t reliably tell you which type you have. Research shows that the severity of symptoms doesn’t always match the actual extent of tissue damage inside the tooth. Some teeth with irreversible damage cause surprisingly little pain, while some with reversible inflammation hurt intensely. Your dentist needs additional information beyond your pain description to make the call.
How Dentists Diagnose It
Diagnosis typically starts with your description of the pain: when it started, what makes it better or worse, whether it’s spontaneous, and how long it lingers after a trigger. Your dentist will also take X-rays to look for deep cavities, cracks, or signs of infection around the tooth’s root.
To pinpoint which tooth is causing the problem, dentists use sensibility tests. The most common is a cold test, where a chilled spray is applied to individual teeth. A healthy tooth responds briefly and the sensation fades quickly. A tooth with reversible pulpitis may respond more intensely but still settles down. A tooth with irreversible pulpitis often produces pain that continues well after the cold source is removed. Electric pulp testing, which sends a small current through the tooth, is another option. These tests check whether the nerve inside the tooth is responsive, but they don’t directly measure blood flow, so they have limitations.
Your dentist may also tap on teeth to check for tenderness, which can indicate that inflammation has spread beyond the pulp into the surrounding bone.
Treatment for Reversible Pulpitis
When pulpitis is caught early and the pulp is still viable, treatment focuses on removing whatever is irritating it. If a cavity is the cause, your dentist will clean out the decay and place a filling. A protective liner may be placed over the area closest to the pulp to encourage healing and the formation of new protective dentin. If a cracked or leaking filling is the problem, replacing it often resolves the inflammation.
After treatment, the tooth may remain sensitive for a few days to a few weeks, but the pain should gradually diminish. The pulp has a natural ability to wall off threats by laying down new dentin as a barrier, and once the source of irritation is gone, this repair process can proceed.
Treatment for Irreversible Pulpitis
Once the pulp is irreversibly damaged, it needs to be removed. You have two main options: root canal treatment or extraction.
A root canal involves removing the inflamed or infected pulp, cleaning and shaping the canals inside the root, and filling the space with a sealing material. The tooth is then restored with a crown or filling. Without its pulp, the tooth loses its ability to sense temperature, but it remains functional for chewing and maintains your jaw structure. Most people feel significant relief quickly after the procedure because the source of pressure and inflammation is gone.
Extraction is the alternative when the tooth is too damaged to restore, when there isn’t enough healthy tooth structure to support a crown, or when cost is a factor. After extraction, options for replacing the missing tooth include an implant, bridge, or partial denture.
Managing Pain Before Your Appointment
Over-the-counter anti-inflammatory pain relievers like ibuprofen are generally the most effective option for pulpitis pain because they reduce both inflammation and pain signaling. Acetaminophen can help with pain but doesn’t address the inflammation itself. Some dentists recommend combining the two for more effective relief, since they work through different mechanisms. Avoid placing aspirin directly on the gum near a sore tooth, as this can burn the tissue. Cold or hot foods and drinks that trigger pain should be avoided until you can be seen.
These measures are temporary. No amount of pain medication will resolve the underlying problem, and delaying treatment gives the infection more time to spread.
What Happens if Pulpitis Goes Untreated
Untreated irreversible pulpitis doesn’t just stay in the tooth. As the pulp tissue dies, bacteria multiply and the infection can spread through the tip of the root into the surrounding jawbone, forming a periapical abscess. This often causes swelling, a bad taste in the mouth, and pain when biting down.
From there, the infection can extend into the soft tissues of the face and neck. In rare but serious cases, it can progress to a deep neck infection, which may compromise the airway. If bacteria enter the bloodstream, the resulting sepsis can affect the heart and other organs. These severe outcomes are uncommon with timely dental care, but case reports in the medical literature document deaths from dental infections that were identified too late. The progression from a simple toothache to a life-threatening situation is preventable with early treatment.