What is pulp capping? Can root canal treatment be avoided with deep decay?

At the very centre of the tooth is the pulp, the living tissue that contains the nerves and blood vessels. As decay advances through the enamel and the dentine beneath it and approaches the pulp, the pulp becomes inflamed (pulpitis). In the classic approach, if the pulp is exposed or the inflammation has progressed, root canal treatment is done and the pulp is removed completely. Methods known as vital pulp therapy, on the other hand, aim to keep the tooth alive by preserving all or part of the pulp. According to the 2021 position statement of the American Association of Endodontists (AAE), these methods are indirect and direct pulp capping, and partial and full pulpotomy.

In indirect pulp capping, a thin layer of dentine is left over the pulp while deep decay is being cleaned out, and this layer is covered with a protective material and filled. The pulp is never exposed. In stepwise decay removal, the decay closest to the pulp is left in the first session, the tooth is closed temporarily, and months later, in a second session, after the pulp has produced defensive dentine, the remaining decay is cleaned out. In selective decay removal, the tooth is filled permanently without the soft dentine closest to the pulp being removed at all.

In direct pulp capping, by contrast, the pulp has been exposed. The exposure can happen while the decay is being cleaned out, or accidentally in a sound tooth, for example while preparing it for a crown. The bleeding at the exposed point is brought under control and the pulp is covered directly with a material. In partial pulpotomy, a few millimetres of the pulp at the exposed point are removed; in full pulpotomy, all the pulp in the crown part of the tooth is removed and the pulp in the root is preserved. In Turkish-language sources the definitions of indirect and direct pulp capping are sometimes confused; the distinction rests on whether or not the pulp has been exposed.

With deep decay, the strongest evidence comes from the value of the pulp never being exposed. In a randomised trial involving 314 adults at six centres in Scandinavia, for decay involving three quarters or more of the dentine, stepwise removal markedly reduced pulp exposure compared with removing the decay completely in a single session, and increased the proportion of teeth whose pulp stayed vital and whose root tip stayed healthy after one year. The 2021 Cochrane review also found that, for deep decay in permanent teeth, complete removal of the decay was associated with more failures than stepwise or selective removal; however, the certainty of the evidence was moderate to very low in most comparisons.

The most striking finding of the same Scandinavian trial concerns teeth whose pulp was exposed by decay. The 58 patients whose pulp was exposed were assigned to direct pulp capping or partial pulpotomy; at follow-up beyond one year, the proportion of teeth whose pulp stayed vital and whose root tip stayed healthy was 31.8% with direct pulp capping and 34.5% with partial pulpotomy, and the difference was not significant. The authors concluded that vital pulp therapy has a poor prognosis in these conditions and recommended the stepwise approach, which focuses on not exposing the pulp with deep decay. The results are markedly lower than the rates in the studies mentioned below, which used newer materials; patient selection and the definition of success also differ between the studies.

The material matters. In a randomised trial involving 376 patients in 35 practices in the USA, the likelihood of failure (needing root canal treatment or extraction) after 2 years of direct pulp capping was 31.5% with calcium hydroxide and 19.7% with MTA. According to the AAE position statement, in permanent teeth diagnosed with irreversible pulpitis, success rates at 1 to 2 years of between 85% and 100% are reported for vital pulp therapies (pulp capping and pulpotomy together) using MTA and other calcium silicate cements; with calcium hydroxide, glass ionomer and resin-based materials, this range is 43% to 92%.

There is an important disagreement between specialist societies, and knowing about it helps you understand your dentist's approach. European studies and the Cochrane review support stepwise or selective removal, leaving some of the decay in order not to expose the pulp with deep decay. The AAE, on the other hand, argues in its 2021 statement for complete removal of infected dentine, for direct examination of the pulp under magnification if it is exposed, and for deciding accordingly how much pulp tissue to preserve; it writes that remaining decay can lead to ongoing hidden inflammation in the pulp. The European Society of Endodontology (ESE) also published a separate position statement on the management of deep decay and the exposed pulp in 2019.

What really determines the chances of pulp capping is the inflammatory state of the pulp, but this cannot be measured precisely before treatment. The AAE writes that cold and electric tests actually measure not the vitality of the pulp but its sensitivity, that an exaggerated and lingering pain response to cold indicates more severe inflammation, and that pain when the tooth is tapped suggests that the pulp is irreversibly inflamed. The statement notes that direct observation of the exposed pulp under a microscope, and whether the bleeding stops, give additional information, and that in recent years it has been debated whether some pulps with symptoms may also be candidates for vital pulp therapy.

The final decision is made according to the examination, tests, X-ray and the appearance of the pulp during treatment. Telling your dentist about the signs below makes the decision easier.

The course below is a general framework. Which steps are carried out is determined by the depth of the decay, the condition of the pulp and the approach your dentist follows.

1. 1

   Diagnosis

   The dentist asks about the history of the pain, does a cold test and a tapping test, and takes an X-ray. Pain that starts on its own, pain at night and pain that lingers after cold are important clues to the condition of the pulp; mention them without being asked.

2. 2

   Anaesthetic and isolation

   The area is numbed with a local anaesthetic. The tooth is surrounded with a rubber sheet (rubber dam) to protect it from bacteria in saliva; this step is important in a procedure where the pulp may become exposed.

3. 3

   Cleaning out the decay

   Depending on the dentist's approach, the decay is either cleaned out completely or the part closest to the pulp is left. In the stepwise approach, the tooth is closed temporarily at this session and the remaining decay is removed months later at a second session.

4. 4

   Controlling the bleeding if the pulp has been exposed

   According to the AAE, bleeding is usually brought under control by rinsing the exposed pulp with sodium hypochlorite solution for 5 to 10 minutes or with a cotton pellet soaked in this solution. If the bleeding does not stop, the deeper part of the pulp may also be inflamed; the dentist may move on to partial or full pulpotomy.

5. 5

   Placing the protective material

   The pulp, or the dentine close to the pulp, is covered with MTA or another calcium silicate cement, and sometimes with calcium hydroxide. These materials support the pulp in forming a new bridge of hard tissue beneath them.

6. 6

   An immediate sealed filling

   The AAE writes that closing the tooth immediately with a permanent, sealed filling after vital pulp therapy is a strong determinant of success. If the tooth needs to be covered with a crown, this is planned after a symptom-free waiting period.

7. 7

   Follow-up

   At check-ups you are asked about any symptoms in the tooth, the cold test is repeated and an X-ray is taken when needed. Whether the pulp stays vital and whether inflammation develops at the root tip only becomes clear over time.

With deep decay, the options are ranked by how much of the pulp is preserved. Which one is suitable depends on the condition of the pulp and the dentist's findings.

When pulp capping succeeds, it keeps the tooth alive and prevents root canal treatment. When it fails, it often only buys some time. The points below help you set your expectations correctly.

The course after pulp capping varies from tooth to tooth. The points below are the usual course; the follow-up plan your dentist gives you takes priority.

1. The first few days

   There may be some sensitivity in the tooth to cold and to biting. The sensitivity is expected to ease gradually; if it increases or turns into pain that starts on its own, this is an important sign.

2. The first few weeks

   If stepwise removal was done, the tooth is closed with a temporary filling. During this period you need to protect the temporary filling and not miss the date of the second session.

3. If a crown is needed

   The AAE recommends a symptom-free waiting period and an assessment of the tooth's risk of fracture before the tooth is covered with a crown after pulp capping.

4. Long-term check-ups

   In studies, teeth that had pulp capping were followed for 1 to 2 years and longer. Your dentist checks whether the pulp has stayed vital using the cold test and X-rays.

We do not give figures here, because the scope varies with the depth of the decay and the approach chosen. The items that determine the price are:

Approach and number of sessions

Single-session indirect pulp capping and two-session stepwise removal or pulpotomy are different procedures.

The material used

MTA and other calcium silicate cements are different cost items from calcium hydroxide; in studies they were found to be associated with better results.

Filling or crown

The permanent filling or crown placed over the pulp capping is a significant item in the total.

Likelihood of failure

If pulp capping does not work, root canal treatment is needed. Take this possibility into account when making the decision.