Pulpitis is inflammation of the dental pulp (nerve), the soft tissue at the centre of a tooth that contains nerve fibres and blood vessels. Pulpitis is one of the most common causes of toothache. Whether the pulp can recover depends on whether the inflammation is reversible or irreversible.
A tooth is made up of an outer layer of enamel, with dentine underneath. Both enamel and dentine are hard. The pulp (nerve) sits in the middle of the tooth, enclosed by these hard walls, so when the pulp becomes inflamed there is very little room for swelling. That lack of space is part of why pulpitis can be so painful.
Pulpitis is caused by bacteria reaching the pulp. Bacteria can get in through deep decay, a cracked tooth, a leaking or failing filling or crown, or damage from repeated or extensive dental work on the same tooth, or from trauma such as a knock to the tooth. The pulp reacts to the bacteria, and to the toxins the bacteria produce, by becoming inflamed.
In reversible pulpitis the pulp is irritated but still healthy enough to recover once the cause is removed. Typical symptoms are a short, sharp pain with cold, sweet or sometimes hot food and drink, which stops within a few seconds of the trigger being removed. The tooth does not ache when left alone.
Treatment means removing the cause, usually by treating the decay or replacing a leaking restoration. The pulp then settles, and no root canal treatment is needed.
In irreversible pulpitis the inflammation has progressed to the point where the pulp will not recover on its own. Typical symptoms include pain that lingers for a minute or more after hot or cold, aching that starts without any trigger, pain that wakes you at night, and pain that is hard to pin to one tooth or spreads to the ear, jaw or temple. In later stages a tooth can become sensitive to heat, with cold water bringing relief.
Irreversible pulpitis can also develop with few or no symptoms, and some cases are found only on an X-ray or during treatment of deep decay.
Treatment is root canal treatment, which removes the inflamed pulp, then disinfects and seals the canal system.
Symptoms alone are not always reliable, so diagnosis combines your history (what triggers the pain, how long the pain lasts and whether the pain wakes you), a cold test to check how the pulp responds, percussion and bite testing to check whether inflammation has reached the tissues around the root, and periapical X-rays, with a CBCT scan where more detail is needed.
Without treatment, an irreversibly inflamed pulp eventually dies (pulp necrosis). The pain may stop at this point, but the tooth has not healed. Bacteria can then infect the root canal system and spread to the bone around the root tip, causing apical periodontitis or a dental abscess. Common signs are tenderness on biting, gum swelling or a small gum boil near the tooth.
See your dentist, especially if pain lingers, starts on its own or keeps you awake. Over-the-counter pain relief such as paracetamol or ibuprofen, taken as directed, can help in the short term. Antibiotics do not treat pulpitis, because the problem is inflammation inside the tooth rather than a spreading infection.
If you have facial swelling that is spreading, or any difficulty swallowing or breathing, seek urgent medical care straight away.
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