What happens to a tooth's existing dental crown during root canal treatment? / Can it be reused?

Root canal treatment is sometimes required for teeth that have already been fitted with a dental crown. In fact, this is a relatively common occurrence.

Related pages about restoring root canalled teeth.

Here's information about how this situation is handled, both during and after the tooth's treatment.

The access cavity through which root canal treatment is performed.

The game plan.

As explained in our outline of the root canal procedure, one of the first things a dentist does is create an access cavity. This is the hole through which the tooth's work will be performed.

A) If possible, they'll remove the tooth's existing crown before creating this access. In practice, however, this is typically easier said than done.

B) If the dentist determines that the tooth's crown won't come off (or at least not easily or predictably), then they'll have to drill a hole right through it.

The access cavity for the root canal treatment has been made right through the crown.

What's the outcome for the crown?

In this type of situation, a patient may wonder what will become of their tooth's crown. Will it be damaged? Can it still be used? Will it need to be replaced?

As you'll find explained on this page, the answer is typically, yes, the existing crown can possibly still be worn. But it's probably a better choice to go ahead and replace it. Listed below are several of the factors that must be considered when making this decision.

C) Can the crown be reused? - Factors to consider.

1) Will the crown still be capable of protecting the tooth?

A dentist may make the access cavity right through the dental crown.

The degree to which a crown is damaged by creating an access cavity through it will vary.

The size of the hole will be a factor, as well as the type of material from which the crown has been made.
(Related page: Dental crowns: Types / Construction.)

a) Crowns made with metal.

Drilling a hole through an all-metal (gold) or porcelain-fused-to-metal crown may not significantly affect its strength.

b) Ceramic crowns.

Creating a hole through some types of all-ceramic (all-porcelain) crowns may very well weaken them, possibly significantly.

Will the crown still be strong enough?

Clearly if the structural integrity (strength) of the crown has been compromised and it can no longer be relied upon to protect the tooth from fracture, it will need to be replaced.

Additionally, it could be that the act of creating the access cavity has created significant changes with the tooth itself.

Possibly it is now so hollowed out that it no longer provides a solid foundation for the original crown. If so, a new one (with a more encompassing design and possibly a post and core) will need to be made.

Filling a crown's access cavity with a dental filling.

2) Will reusing the original crown create an adequate seal?

If the structural integrity of the existing crown does seem reasonable, the dentist will complete the tooth and crown's repair by way of placing a dental filling (dental amalgam or dental bonding).

This solution is a very cost-effecting one, in the sense that a repair is made for the price of a filling, as opposed to new dental crown. However, there are concerns with this type of fix.

Coronal leakage - A situation where bacteria seep past a filling.

One of the most important is whether or not the filling can create an adequate seal for the tooth. One that will help to insure the long-term success of the root canal treatment by preventing coronal leakage (a major cause of root canal failure).

A dental crown provides an excellent seal for a tooth that has had root canal treatment.

The difficulty in creating a substantial, lasting and predictable seal would be a major criticism of the crown/filling patchwork solution.

This may be more of an issue for back teeth, which have a constant exposure to heavy chewing forces, than front ones.

Which makes the best choice, reusing the existing crown or make a new one?

The alternative to patching the existing crown is to just go ahead and make a new one. And this solution probably offers the greatest level of predictability and longevity.

If the amount of time, effort and money involved with placing a new dental crown were of no concern (which, we admit, is never the case), it seems likely that almost any dentist would consider placing a new crown the superior choice.

Your dentist may be able to remove your current crown prior to performing your treatment.

Removing a tooth's dental crown before its root canal treatment is performed, and then recementing it afterward, can be an excellent plan. However, as ideal as it sounds, the practical application of this approach can be quite taxing, both for the dentist and the patient.

Removing a crown is easier said than done.

A crown can be exceedingly difficult to remove from its tooth, and it's possible that it will be damaged in the process. As a worst-case scenario, the tooth itself might be damaged, possibly significantly so.

Bottom line, a dentist may try to remove a patient's crown before performing their root canal treatment. But if it doesn't come off easily, they will probably back off on this approach promptly.

 All FYI's ► 
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