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 crown. Dental crown basics.
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 core replaces lost tooth structure that’s needed for crown stability.
A) What is a “core”?
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)
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?
▲ 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. What’s this? That’s because a post is placed in a tooth’s root inside the space previously occupied by tooth nerve tissue. (See picture below.)
X-ray of a 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?
- 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.
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.
▲ Section references – Raedel, Heydecke, Willershausen
How much do post and cores cost?
Here is an estimate of the fee your 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. The steps.)
- 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. Defined. As such, benefits typically run on the order of 50% of the procedure’s UCR fee. How this is calculated. To receive maximum benefits, the policyholder 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 Examples. 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 1950s and ’60s, 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?
- Two studies (Jung, Gomez-Polo) evaluated the success of teeth from a standpoint of the type of post used (prefabricated vs. cast How they’re different.).
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.
▲ Section references – Raedel
Related pages about restoring root canalled teeth.
- When is a crown required after root canal treatment? The factors that decide.
- Can the tooth’s original crown just be reused? Considerations.
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.
Heydecke G, et al. Fracture strength and survival rate of endodontically treated maxillary incisors with approximal cavities after restoration with different post and core systems: an in-vitro study.
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.
Comments.
This section contains comments submitted in previous years. Many have been edited so to limit their scope to subjects discussed on this page.
Comment –
Post after root canal ?
just had a root canal, did not complete previous root canal due to the fact that i hate dental work. so.. tooth that the root canal was started on cracked 5 months later..re did the work. now doc says i need a post before crown.. is this a must? i am trying to do just one last visit.. but getting a post plus crown may take 3 visits..
kc
Reply –
Crowns are routinely used to rebuild damaged teeth that have also had root canal. And how well the crown will stay in place (stay cemented) has a lot to do with how much tooth structure it cups over.
If a great portion of the tooth’s structure has been lost (you mentioned that your tooth deteriorated during the past half-year), the dentist will place a dental core to replace the missing tooth structure. If the dentist doesn’t think the dental core will stay in place well on its own, they will place a post that helps to anchor the core to the tooth.
So, evidently your dentist feels that a post is needed. It’s purpose is to help to insure the long-term success of your tooth’s treatment (helping to insure the crown stays in place).
Staff Dentist
Comment –
Troublesome post.
About thirty years ago I damaged the nerve in one of my front teeth at this time I had a root canal done. In June when visiting my dentist he remarked how black me front tooth had become. He said that I should consider having a crown fitted, I maid an appointment for this to be done, after a week I went back and he created a post from the damaged front tooth. He fixed a temporary crown and told me it would be about two weeks to get a new crown, when the crown arrived it was the wrong colour so had to be remade. After another week or so the temporary crown came off, so I went back to the dentist to have it replaced. A lady dentist replaced it with what I can only say is a substance which was expelled from a gun and molded to shape. A few days later I went back to the male dentist to have the new crown fitted.
The dentist had a hard job to pull off the temporary crown so much so that I felt a cracking sound and feeling, I asked it my tooth was ok and was told it’s fine, after fitting the new crown I left. About two weeks later wile getting in my car the crown fell off including the post maid from my tooth. I returned to the dentist the lady dentist replaced the crown with what she called a flexible post how ever this was very flexible. I did complain but was told that if it came off, she would fit a new crown with a steel post. By December I returned and she agreed that she would fit a new crown an steel post the new post was fitted three days ago and despite telling her that it was still very loose she said it was fine. However this morning Saturday it dropped out I contacted the helpline but they was unable to help, it appeared to me that there were no adhesive on the post but only around the tooth. What would advise me to do now
j b
Reply –
Generally, a core is placed to idealize the shape of the tooth (replace portions of missing tooth structure) so the trimmed-down nub of tooth the crown fits over is ideal in shape (this aids with crown retention). The purpose of a post is to anchor the core.
Posts can be made out of flexible (fiber) or rigid (metal, ceramic) materials. Each type has its own advantages. Neither type is best for all considerations.
The important question here is why three attempts at anchoring a post have failed.
It could be a failure with the materials used (cement, bonding), kind of like you explain. But a post should not be held in just by the grip of its “cement.” Its Resistance Form (resistance to being dislodged due to its shape and fit inside the tooth) is a more important factor.
“Adhesive” cements have only been available in dentistry over the last 30 years or so. For many many decades prior to that, dentists were able to place successful post and cores just with cements that acted as “fillers” between the cemented parts. They worked due to the mechanical design of the post/tooth relationship.
Having said that, for future attempts, probably your dentist will choose a cement known to bond to both tooth structure and metal. That can certainly be an aid.
Repeated failure could also be due to the fact that something is amiss with the “bite” of your crown(s). If it is too prominent in some aspect (like possibly just when you slide your teeth a certain way) and the tooth receives excessive forces, the post might get dislodged.
In your case, it seems you have had multiple crowns on your tooth. It seems unlikely that each one would have been crafted with the same “bite” discrepancy.
Another issue that may be playing a role is the lack of a crown/crown preparation ferrule effect. Go to Google images and type in “crown ferrule” and look at the pictures for an explanation.
A crown ferrule has to do with the way the edges of a crown rest on the tooth. This effect helps to direct forces to the tooth itself. A short, incomplete or nonexistent ferrule would allow a higher level of force to be directed to the post and core complex (thus dislodging it).
The cure in this case would be to replace the post and core, then re-prepare the tooth (reshape it so a more substantial ferrule design exists). A new impression would then need to be taken and a new crown made (to fit the new shape of the tooth).
Only your dentist can determine what is going on and what solution is needed. Good luck.
Other than being successful with the post and core, there’s no other avenue for rebuilding your tooth as it exists.
Conceivable some type of design could be contrived where a neighboring tooth shares in receiving some of the force directed to the tooth (like making a 2-unit bridge or such) but that wouldn’t typically be considered a first-choice approach like getting the post anchored successfully would.
Staff Dentist