Crown – Post and Core
Very little part of my tooth is left in my mouth. Would you be able to save my tooth or will it have to go for an extraction?
At times, when a lot of the tooth structure is lost, post and core could be the only option left to save the natural tooth.
What is post and core?
When very little crown structure of the tooth is left, the only way left to save the natural tooth structure is to take support from the root.
A root canal is carried out for the tooth that has to be saved and a metallic or a fiber post is inserted in to the canal of the tooth. The canal of the tooth that is going to receive the post has to be of sufficient length so that it can provide support to the crown portion.
After the root canal is completed, the post is generally inserted for about two-thirds the length of the root canal. Any tooth structure remaining that has caries will have to be removed before taking an impression. A core is then built upon the post .The core is the portion of the built up tooth that will eventually receive the crown.
A portion of the tooth is embedded under the gum. Can the tooth still be saved?
At times a surgical lengthening of the tooth might have to be carried out by removing a portion of the gum and the bone to expose the margin of the tooth that will receive the crown. This procedure is known as crown lengthening
How many sittings will the post fabrication take?
After the root canal and the crown lengthening procedures have been carried out, there is an option of either getting a prefabricated post or a custom made post done.
For the custom made post, space preparation is done in the root canalled tooth and impression of the same is made and sent to the lab. The post can be made of either metal or zirconium.The desired shade of the crown is also recorded. Once the fabricated post along with the crown arrives and the post fits snugly into the canal, it is cemented into the canal and the crown is cemented over it.
The prefabricated posts are generally available in the clinic. Once the post preparation is done inside the canal, the prefabricated post of the correct size is selected and cemented inside the canal. The prefabricated posts are of two types. One is the fiber post which is white in colour and mostly used in the front teeth. The second one is the metal post which is generally used for the teeth at the back of the mouth. These are fitted in place and a core build up of the tooth is done. An impression of the core is made and sent to the lab along with the shade of the tooth selected. The crown is fabricated in the lab and once it arrives at the clinic, it is cemented over the post and core.
Are post and core successful?
The success of the post depends upon:
- Which area of the mouth requires a post
- What is the length of the root
- The periodontal condition of the tooth
- The crown root ratio
- The caries index of the mouth
- If the patient has any parafunctional habits
Studies have shown that the average survival time of the post and cores was 7.3 years. The cumulative failure rate was 11.2%. The most common complication was loss of retention of the post and core.
What happens if the post and core fails?
If the post and core fails, the tooth will have to be extracted and replaced with either an implant or a bridge.