Rebuilding your tooth after root canal treatment.

- Dental crowns vs. fillings. / Success rates. / How soon does a final restoration need to be placed?

Crown or
filling?

Link to crown vs. filling section.

Advantages
of crowns.

Link to research about placing a crown after endodontic treatment section.

Every tooth will need a final restoration.

After a tooth's root canal therapy has been completed, it will require some type of permanent dental restoration.

This page discusses the different options you have in deciding how your tooth is rebuilt (crown vs. filling), and details that need to be considered when selecting between them.

Considerations:

You may also be interested in these additional topics about rebuilding root canalled teeth:


A) A crown or a filling after root canal - Which makes the best choice?

For the most part, the two basic options that you have for restoring an endodontically treated tooth are the placement of a dental crown or else a filling.

Here are some of the issues that need to be considered when choosing between the two.

An access cavity tends to weaken a tooth.

Teeth that have had treatment may require strengthening.

1) The tooth may need strengthening.

Teeth that have had root canal therapy can be fragile, possibly significantly so. Here are some reasons why:

Damage during treatment.

When performing root canal, a dentist must create an access cavity (opening) in the tooth through which its work will be performed (see picture). Making this hole tends to weaken the tooth.

This is especially true in cases where the tooth's individual root canals have been difficult to locate. When this situation occurs, the dentist may need to remove comparatively greater amounts of internal tooth structure, to the point where the tooth may become significantly hollowed out.

After its endodontic therapy, this tooth will require a crown.

This tooth is very hollowed out and should have a dental crown placed.

Previous damage.

Many teeth that require root canal have already experienced some type of catastrophe (such as having a large cavity or major damage due to fracture) and are already in a weakened state due to that event.

Changes in tooth dentin.

The flexural strength of dentin (the hard, calcified tissue that makes up the bulk of a tooth) is likely reduced by the various chemical agents frequently used during the cleaning phase of root canal therapy (Eliyas 2015). [page references]

Each of the above suggest that by the time its root canal treatment has been completed a tooth may be at substantial risk for fracture, even when exposed to normal chewing forces.

If so, a dentist will frequently recommend that a crown should be placed. Dental crowns provide a strengthening effect that can help to prevent fracture.

Coronal leakage - Bacteria seeping past a dental filling.

If contaminates re-enter a tooth, its completed treatment will fail.

2) The tooth will require a proper seal.

If contaminates from the mouth find a way to seep past a tooth's dental restoration (a phenomenon termed "coronal leakage"), its root canal treatment can fail.

A dental crown, more than any other type of restoration, can help to predictably prevent this type of event. (Use the link above for a more detailed explanation.)

3) Restoration longevity / durability is an important factor.

The final restoration that a dentist places must be one they feel can provide lasting service. The specific physical properties that the restoration needs, however, will vary on a case-by-case basis.

Examples.

a) Relatively intact teeth.

It's possible that a tooth that ...

  1. Just has a conservative access cavity ...
  2. And no other history of significant tooth structure loss (such as a previous cavity, filling or breakage)

... might be successfully restored with just the placement of a dental filling.

This approach may be best suited for front teeth (incisors and canines) where the direction of force applied is typically non-axial.

With back teeth (premolars and especially molars), forces are more commonly directed straight down (axially) and for this reason providing for tooth reinforcement (like that created by crown placement) may make the more prudent choice. (Eliyas 2015)

b) More involved cases.

In comparison to teeth still in relatively pristine condition. those with large fillings or extensive decay, or teeth that fractured prior to their receiving root canal treatment, are probably best restored with a dental crown. (A dental post and core may be required too.)

This approach may be needed for either front or back teeth. Crown placement is especially appropriate for molars, a type of tooth that must be able to withstand heavy chewing forces.

What type of final restoration makes the right choice for your tooth?

  • Increasingly, placing a dental crown on an endodontically treated molar has become the "standard of care" in dentistry (see below).
  • For other teeth, especially relatively intact front ones and even possibly premolars, the placement of a dental filling may be perfectly satisfactory.

Related page: Can a tooth's existing crown be used after its root canal therapy is finished?


B) Dental research confirms the benefit of dental crowns.

An x-ray showing completed endodontic therapy and a dental crown.

X-ray showing a tooth's completed treatment and dental crown.

Several studies have evaluated the outcomes of teeth that have had root canal treatment and then were, or were not, crowned. Here are the findings of some of those studies.

1) Aquilino (2002) - This study evaluated the track record of 400 endodontically treated teeth and found that those that were not crowned were lost at a rate 6 times greater than teeth that had dental crowns placed.

2) Nagasiri (2004) - This study evaluated 220 molars that did not receive dental crowns after root canal treatment. The survival rates of these teeth at 1, 2 and 5 years were 96%, 88% and 36% respectively.

3) Lynch (2004) - This study evaluated 176 teeth for a three year period following the completion of their root canal treatment. The following survival rates were observed for teeth with the following types of restorations: cast restoration (dental crown) - 92%, amalgam restorations ("silver" filling) - 67%, composite restorations (tooth bonding) - 35%.

Learn about the different types of dental crowns.

Click image to jump to topic Dental Crowns.


C) How soon does the permanent restoration need to be placed?

Your dentist will make a recommendation about the time frame that is appropriate for placing your tooth's final restoration (dental crown or filling).

The phrase "as soon as is reasonably convenient" (meaning not an emergency but definitely a priority), often applies to this situation.

Why the rush?

In general, the temporary restoration that has been placed is just that. Here's why:

  • It can't be relied upon to provide adequate protection or strengthening for the tooth over the long term, thus leaving it at risk for fracture.
  • When compared to a permanent restoration, the seal that a temporary creates isn't as lasting, thus placing the tooth at risk for recontamination.
 
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