Coronal leakage – A cause of root canal treatment failure. –

Coronal leakage: What is it?

Dentists, especially endodontists, have become increasingly aware of a process termed “coronal leakage.” This phenomenon involves the situation where oral bacteria and debris find a way of leaking into and recontaminating and infecting the interior of a tooth that has previously had root canal therapy.

Why is it a problem?

Coronal leakage leads to root canal treatment failure and associated symptoms. Once it has occurred, the tooth will require endodontic retreatment so to once again clean/disinfect and then reseal Procedure steps the tooth’s root canal system.

How is coronal leakage prevented?

As this page explains, it’s prevented by way of placing an appropriate final dental restoration for a tooth promptly after its root canal work has been completed. (Frequently a permanent crown, in some cases a filling may suffice.)

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A description of the phenomenon of coronal leakage.

The scenario.

If the filling’s seal is compromised, bacteria can recolonize the tooth’s root canal system.

If this occurs, the conditions inside the tooth will revert back to those that existed before its therapy was performed. The tooth’s previously successful work will now need to be considered failed root canal treatment. (Leaking root canal symptoms.)

As a solution for this change of events, conventional root canal retreatment, apicoectomy, or else tooth extraction will be required. (For more information about these options, use this link: Endodontic retreatment How successful is this? )

And that scenario describes what coronal leakage is.

Coronal leakage is the phenomenon where oral debris and bacteria seep from the patient’s mouth, past an endodontically treated tooth’s dental restoration, and ultimately penetrate into and recontaminate and infect its interior root canal space.

The term “coronal” refers to the fact that the entry of the seepage is via the “crown” portion of the tooth. (The part of the tooth that’s visible above the gum line.)

What research has found.

While the concept of coronal leakage has been known for over 100 years, it’s only since the 1990s that it’s received widespread attention and study.

Bacteria seeping past this tooth’s defective filling has caused its root canal treatment to fail.

How big of a problem is it?

However, with any one case, coronal leakage may be only one factor of several that are involved. Here’s an explanation.

• Teeth having both adequate-quality root canal treatment and final dental restorations had a 2.8 greater success rate than teeth having adequate treatment and inadequate restorations. (Inadequate restorations allow coronal leakage to occur.)

• Teeth having both adequate-quality root canal treatment and final dental restorations had a 2.7 greater success rate than teeth having inadequate treatment and adequate restorations.

Together, these findings imply that:

• Placing a suitable restoration can play an important role in protecting the outcome of a tooth’s therapy.
• But a well-sealing restoration alone can’t overcome problems created by low-quality endodontic work.

▲ Section references – Hoen, Gillen

Recontamination can occur fairly rapidly.

Although a tooth’s root canal system does receive an “endodontic” seal during its procedure (by way of the dentist packing gutta percha inside the tooth How this is done.), the integrity of this seal isn’t able to resist the continued assault of contaminants that takes place when coronal leakage occurs.

Research findings.

• A study by Torabinejad determined that the recontamination of a tooth’s entire root canal system may occur in as little as 2.5 to 6 weeks.
• A more recent study by Eliyas found that bacteria can physically recolonize the full length of a tooth’s sealed root canal system in as little as a few days.

  Even worse, this same study determined that endotoxins, irritating chemical compounds produced by bacteria, can cause contamination of the tooth’s root canal space even more quickly than the microorganisms themselves.

▲ Section references – Torabinejad, Eliyas

Understanding how the potential for coronal leakage might affect your tooth’s treatment.

Replacing a temporary filling promptly helps to protect your root canal work.

A) Coronal leakage as it pertains to temporary dental restorations:

▲ Section references – AAE

B) Coronal leakage as it pertains to permanent dental restorations:

Generally speaking, your tooth’s permanent restoration should be placed as soon as it is reasonably convenient (in other words, don’t drag your feet on scheduling this procedure).

It’s important to adhere to your dentist’s instructions on this matter. Their recommendation will be based on the type of interim (temporary) restoration they have placed in your tooth’s access cavity and the time frame they feel they can rely on the seal it creates.

The final restoration they place will need to:

• Be capable of creating a barrier to seepage/leaking.
• Be durable enough that this seal is maintained, even as the tooth functions under extreme conditions.
• Offer protection for the tooth so the seal is not compromised due to tooth fracture.

What types of restorations can meet these requirements?

Generally speaking, there are three alternatives that might be utilized.

A dental crown can establish an excellent seal but not all root canalled teeth require one.

1. Placing a dental crown. – Without question, the fit of a permanent crown over its tooth typically creates a superior and lasting seal. And for teeth that require strengthening/protection from fracture, placing this kind of restoration makes the right choice.
2. Placing a filling. – Not all root canalled teeth require the protection of a crown. If after its endodontic treatment has been completed the tooth remains primarily intact, the placement of a dental filling (dental bonding or amalgam) has been shown to create an adequate seal. (Eliyas 2015)

   In most cases, the type of teeth that meet this criterion would be those that previously had no, or just a minimal, dental restoration.

3. Patch the tooth’s existing crown. – In the case where a tooth’s root canal work has been performed through an opening drilled through its existing permanent crown Explained, it may be possible that a satisfactory seal can be created by filling the tooth’s access cavity with dental restorative (amalgam or bonding).

Coronal leakage due to an inadequate final restoration (a filling in this case) could explain this case’s treatment failure.

Which makes the best choice for preventing coronal leakage?

In terms of creating a predictable, lasting seal, there is no question that placing a brand-new dental crown following a tooth’s treatment makes an excellent choice, especially in the case of molars.

But this procedure may be judged too aggressive (in terms of the amount of tooth structure lost) for teeth that don’t otherwise require the benefits that a crown can provide (see “rebuilding” link above). If so, placing a filling may be considered appropriate.

Choosing to patch the hole in an existing crown (through which the tooth’s root canal treatment has been performed) with a filling makes the least predictable choice. We explain the reasons why here. Pros / Cons

What symptoms can you expect with coronal leakage?

Once contaminants leaking into your tooth’s root canal system has occurred, you have the potential to experience any of the wide range of symptoms normally associated with endodontic infection.

Common leaking root canal symptoms.

• Tooth sensitivity or discomfort. – Intermittent or persistent pain, either triggered or spontaneous. Throbbing pain. Sensitivity to pressure (like biting on the tooth).
• Tooth abscess. – The presence of swelling (intermittent or persistent). Development of a pus pimple (gum boil) next to your tooth (formally termed a fistulous tract).
• Additional symptoms of tooth infection. – Noticing a bad taste in your mouth or having a bad breath odor.

This link covers the topic of failed root canal symptoms What to look for. in greater detail.