Pulpitis – There are two types of pulpitis reversible and irreversible


Pulpitis is inflammation of the pulp of a tooth. There are two types of pulpitis, reversible and irreversible. When a tooth suffers pulpitis due to cairies it depends on the proximity of the cairies to the pulp of the tooth as to whether the pulpitis is reversible or not.

Pulpitis may arise from;

  • Cairies (most common cause)
  • Trauma e.g. fracture
  • Exposure of pulp during cavity preparation
  • If irritated e.g. chemically – by unlined filling

When the pulp becomes inflamed due to irritation or slight exposure during a cavity preparation it is usually reversible, this is because with application of sedative dressings the tooth can attempt to defend itself by laying down a layer of secondary dentine which protects the pulp and allows the tooth to heal.

If a tooth has suffered trauma it may suffer reversible or irreversible pulpitis – it very much depends on the specific trauma, a dentist will sometimes place a temporary dressing if a fracture has occurred or if a blow to the tooth has occurred they may just keep the tooth under observation, awaiting either improvement or onset of symptoms before deciding on a treatment plan.

Cairies will usually begin in enamel and if remineralisation cannot occur and are left untreated, are likely to progress to the ADJ (amelodentinal junction). At this point secondary dentine will be laid down. As cairies progress further into dentine the tooth will become sensitive- fibrils will be stimulated and the pulp will become inflamed. If the tooth is treated at this point pulpitis is reversible, however, due to the hollow structure of dentine cairies can progress rapidly once at this stage, if cairies are produced quicker than secondary dentine, the tooth tissue close to the pulp chamber becomes involved, the tooth then becomes more painful and the pulp will be too inflamed to be effectively treated with removal of cairies and placement of a sedative dressing. It is at this point that pulpitis is irreversible, and is likely to cause pulp death.

The body’s natural defence mechanism is to increase blood flow to any damaged area; this usually causes swelling/inflammation. In the case of a tooth the ability to swell is limited as the nerves are housed within a solid structure; this causes a build up of pressure and causes intense pain. Because the nerves and blood enter a tooth through such a small opening this pressure can cut off the blood supply to the tooth which in turn causes pulp death.

When the pulp dies the dead tissue decomposes and travels out of the tooth through the apex into bone. The presence of decomposed tissue causes more inflammation which the body tries to deal with by forming pus, and an abscess is made – this is called an alveolar abscess and can be extremely painful. If the body is able to release the pus it will do so by creating a track through the jaw bone to the gum surface, where a small hole will appear and pus will drain through, although this initially reduces pain significantly, it tastes awful. This is a chronic abscess but can become acute at any time!

It is with in depth knowledge of these processes and with use of x-rays, and vitality tests that a dentist is able to determine whether a patient is suffering from reversible or irreversible pulpitis. This is why a dentist will ask a patient to describe their pain, how long they’ve had it, what the tooth is sensitive to, what helps ease the pain etc.  Dentists can also perform vitality tests to see if the reactions of the tooth are normal or not. Standard tests involve;

  • Cold (ethyl chloride held on the tooth with on cotton wool)
  • Heat (heated gutta purcha held on the tooth)
  • Electricity (electronic pulp tester)

When a dentist is certain that their diagnosis is correct they can formulate and discuss with the patient an appropriate treatment plan and proceed with an agreed course of treatment.

About the author

I’ve been a dental nurse for over 13 years, and have worked in various parts of the country in orthodontic practices, general dental practices, within the community dental services, for both NHS and private practices. Within that time I’ve seen quite a few changes, not only with the way services are provided, changes in laws and regulations but also with the use of new materials and more advanced treatments. The one thing that hasn’t changed at all in my time as a dental nurse is the importance of people receiving and understanding clear information about dentistry, treatments, regulations and jobs for example.


  1. Rossie Segroves says:

    thanks for your blog:)

  2. Dental Nurse says:

    Thanks Rossie!

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