Dental posts and cores -
cores.
Rebuilding your tooth after its endodontic treatment.
After your tooth's root canal therapy has been completed, your dentist may recommend the placement of a dental crown.
If so, in some cases they may also inform you that a dental post and core (or else just a core without a post) must be placed before the crown can be made.
Towards understanding the purpose of these procedures and their relationship to each other, we cover the following topics:
- What are cores/posts & cores and when are they needed?
- What is the procedure used to place them?
- How much do they cost? (Does insurance cover them?)
- How long do they last? (Survival rates.)
- Kinds of dental posts.
A) What is a "core"?
Teeth sometimes have large portions missing due to decay, fracture, the loss of a filling or the creation of an access cavity (the hole through which root canal work is performed). If so, a core may be needed.
Placing a core refers to the procedure where a dentist replaces the bulk of a tooth's missing structure, typically in preparation for making a dental crown for the tooth. Doing so creates the optimal shape and foundation for the new restoration.
What materials are used?
A core can be made out of any type of permanent dental restorative. In most cases it's either: 1) Dental amalgam (the metal used to make "silver" fillings) or else 2) Dental composite (the dental bonding used to make "white" fillings). (Shillingburg)
A core replaces lost tooth structure that's needed for crown stability.
Why is a core needed?
Background.
A great deal of a crown's stability depends on the amount of tooth structure that extends into its interior. If very little tooth structure fills this space, the crown will be easily dislodged, especially by lateral forces (those directed from the side).
How a core solves this problem.
By "building up" a tooth first with a core (rebuilding it so it is closer to its original dimensions), the dentist can greatly increase the stability of the crown.
Since after doing so the dentist has the optimal amount of structure (tooth + core) to work with, they can optimize the degree to which it extends into the interior of the crown, thus optimizing its long-term chances for survival.
When specifically is a core needed?
The need for this procedure is a judgment call made by the dentist. However, as a general rule of thumb, cores are typically placed in situations where one half or more of the tooth's clinical crown (the portion of the tooth that lies above the gum line) is compromised or missing. (Shillingburg)
▲ Section references - Shillingburg
B) What is a "post and core"?
The difference between the dental core and post-and-core procedures is that with the latter, a dental post is placed that helps to anchor the core to the tooth.
While a dental core can be created for any tooth, a post and core can only be placed for a tooth that has already had root canal treatment. That's because a post extends into a tooth's root. It's placed inside the space previously occupied by its nerve. (See picture below.)
X-ray of tooth that has a post & core and dental crown.
The post is positioned in the tooth's root. It's attached core extends up inside the tooth's crown.
Is a post always needed?
As general rules of thumb:
- If more than half of a tooth's original crown portion (the part of the tooth normally visible above the gum line) has been lost, a post is needed to assist with anchoring the core to the tooth.
- If more than half of the tooth's crown still remains, a core by itself will probably suffice.
Posts don't strengthen teeth.
In decades past there was a misconception that metallic dental posts played a role in reinforcing (strengthening) the teeth in which they were placed.
To the contrary, dental research has since shown that posts provide no reinforcement benefit and in fact can actually weaken teeth and place them at increased risk for fracture. (Raedel)
Enough of this tooth's crown portion remained following its root canal procedure that no post was required.
Research.
Heydecke - This study determined that case failures where a post had not been placed were more likely to be "repairable." (Meaning that procedures could be performed where the damaged tooth could still be salvaged.)
Failures involving a post were more likely to result in tooth extraction due to the damage involved (such as root fracture).
Willershausen - This study evaluated 775 endodontically treated (root canalled) teeth, some of which had been restored with a post and core.
- It was determined that as a group, these teeth had a complication rate of 6.6%. (This included events such as root fracture.)
- In comparison, the subgroup composed of just those teeth having metal posts had a complication rate of 13.2% (twice as high).
The findings above aren't meant to suggest that post placement is a "bad thing." However, a dental post should be recognized as just an aid in helping to anchor a dental core and provides no role in strengthening a tooth.
If enough natural tooth structure still exists (per the rules mentioned above), then no post is needed and for good reason one should not be placed.
▲ Section references - Raedel, Heydecke, Willershausen
How much do post and cores cost?
Here is an estimate of the fee you dentist might charge for the procedures discussed on this page.
- Core (only).
$205.00 - $365.00 - Prefabricated post and core.
$252.00 - $436.00(A prefabricated post and core is the type whose placement we describe on this page.)
- Cast post and core.
$288.00 - $498.00(A cast post and core is a one-piece unit that is custom made in a dental laboratory and then is cemented in the tooth. Placing one is a two-appointment process. While its construction is different, it serves the same function as a prefabricated one.)
About the fees shown.
Low fee = Small rural city or town.
High fee = Large metropolitan area.
How did we come up with these estimates?
Does dental insurance cover post and cores?
When covered, this procedure is usually categorized as a "major" dental service. As such, benefits typically run on the order of 50% of the procedure's UCR fee. To receive maximum benefits, the policy holder will need to have met their plan's deductible.
If your plan covers dental crowns, it probably covers post and cores too.
Common insurance limitations.
- Some plans don't cover cores alone (as in without post placement).
- When covered, these procedures typically carry the same general restrictions that the policy involved applies to dental crowns. This can include waiting periods, age restrictions and limitations on replacement.
- Coverage for post and cores may be limited in frequency (as in one per tooth per 5-year period).
How much does your dentist pay for a post and core?
There are a lot of procedures in dentistry where the cost of the main item itself only makes up a small percentage of the dentist's overall expenses when performing the service, and thus fee charged. Post and core placement is one of these.
Dental laboratory fees for dental post and cores: (Your dentist's cost.)
- Cast post and core - $20.00 to $35.00
- Prefabricated post, metal - $10.00 to $18.00
How long do cores last?
As compared to post and cores, dental core placement by itself is a comparatively less involved procedure.
As such, one might expect that core (only)/crown combinations typically demonstrate a high survival rate. Unfortunately, we could not find a contemporary source that had investigated this issue.
Based on studies performed in the 1950's and 60's, Shillingburg (linked above) states that cores have been found to be able to provide successful service for severely damaged teeth restored with cast restorations (i.e. dental crowns) for periods of nearly 50 years.
How long do post and cores last?
There have been a number of studies that have evaluated different aspects related to the survival of teeth having post and cores.
- Two studies (Jung, Gomez-Polo) evaluated the success of teeth from a standpoint of the type of post used (prefabricated vs. cast).
It was determined that both types generally offered the same expected rate of success - Jung: 90% vs. 94% at 8.5 years. Gomez-Polo: 83% vs. 85% at 10 years. (Cast vs. prefabricated posts respectively.)
- A study by De Backer evaluated teeth whose restoration included a post and core (and hence had had root canal treatment) vs. vital teeth (teeth that have a live nerve and therefore no post). It determined that the survival rates were similar: 75% vital vs 79% RCT.
▲ Section references - Gomez-Polo, Jung, De Backer
How long will your tooth last?
It should be pointed out that crown failure usually does not involve tooth loss, whereas post and core failure more commonly does (often due to complications associated with root fracture).
One study (Raedel), concluded that on average teeth restored with cast post and cores survived for 13.5 years (from post insertion to tooth extraction).
It was specifically discussed in the paper that this span seemed short. Their explanation was that they felt that cast post and cores (as opposed to prefabricated ones) were typically placed in the most severely damaged teeth, thus explaining the group's low survival rate.
Long-term success likely depends on your tooth's initial conditions.
The findings above suggest that when determining the prudence of saving a tooth (via performing root canal treatment and then rebuilding it with a post and core and crown), that what technically is possible (dental "heroics") may not equate with making the best choice.
By definition, posts are only placed in teeth where so much structure is missing that a core cannot otherwise be adequately anchored. And if your tooth's status is an extreme example of this condition (ask your dentist for their opinion), choosing another route instead (such as dental implant placement, we compare these treatment approaches here) may make the wiser choice.
▲ Section references - Raedel
Related pages about restoring root canalled teeth.
Update log -
1/23/2018 - Graphic added.
- Root canal (endodontic therapy) basics.
- What is it? / What does it do? - Treatment goals and objectives.
- Answers to root canal FAQ's.
- Diagnosing a need for root canal therapy -
- Signs and symptoms of needing treatment.
- Diagnostic testing your dentist performs.
- X-ray diagnosis.
- Sinus tracts (fistulous tracts, gum boils).
- Having root canal treatment -
- The steps of the procedure. / What will you experience?
- Appointment details - How many visits, how long?
- Rubber dam - Why is it needed? / Placement & usage.
- All about root canal files.
- Making the procedure's access cavity.
- How many roots and canals does your tooth have?
- How and why a canal's length is measured.
- Does having root canal hurt?
- Endodontist vs. General Dentist - Pros and cons.
- The steps of the procedure. / What will you experience?
- Post-procedure considerations -
- What to expect after having root canal.
- What kind of final restoration will be needed?
- What is a post & core? - The basics.
- The post & core procedure.
- Can a tooth's existing crown be reused after root canal?
- Complications & treatment failures -
- Signs and symptoms of endodontic failure. / Treatment solutions.
- Statistics / Incident rates of endodontic success and failure.
- Technical and procedural issues that lead to case failure.
- Failure due to coronal leakage.
- Persistent Dentoalveolar Pain disorder (PDAP).
- Overview: Root canal treatment alternatives.
- Root canal treatment costs - (By tooth type.) / Details about insurance coverage.
Page references sources:
De Backer H, et al. Long-term survival of complete crowns, fixed dental prostheses, and cantilever fixed dental prostheses with posts and cores on root canal-treated teeth.
Gomez-Polo M, et al. A 10-year retrospective study of the survival rate of teeth restored with metal prefabricated posts versus cast metal posts and cores.
Jung RE, et al. A comparison of composite post buildups and cast gold post-and-core buildups for the restoration of nonvital teeth after 5 to 10 years.
Raedel M, et al. Survival of teeth treated with cast post and cores: A retrospective analysis over an observation period of up to 19.5 years.
Shillingburg HT, et al. Fundamentals of fixed prosthodontics. Chapter: Preparations for Severely Debilitated Teeth.
Willershausen, B. et al. Survival rate of endodontically treated teeth in relation to conservative vs post insertion techniques - a restrospective study.
All reference sources for topic Root Canals.
