Post and core procedure
Post and core procedure is painless and does not even require local anesthesia as the tooth has long been dead after the root canal treatment.
A post and core can only be made for a tooth that has had root canal treatment.
The dental examination will focus on the tooth (or teeth) that need the post and core reconstruction. A dental post should be utilized only when a large part of the crown structure is missing as an aid in helping to anchor the core to a tooth.
The dental examination will always be complemented with a dental X-ray (normally, a periapical radiograph).
What can the X-ray show ?
The length and number of root canals; this is important information as the post is designed based to root canal dimensions.
The successful outcome of the root canal treatment; post and core procedure can only begin once endodontic therapy has been successfully completed.
The bone structure surrounding the tooth; the tooth must be surrounded by solid healthy bone to maximize the chances of success.
a tooth after a successful root canal treatment
X-ray of failed root canal treatment. The dark area at the end of the tooth denotes bone infection
After evaluating the data from the dental examination and the X-rays, the dentist will determine the correct diagnosis and design the post and core device.
When is a post and core not indicated ?
There are certain conditions that make the use of a post and core device inadvisable:
Intense pain, gingival bleeding, suppuration, advanced infections, tooth abscesses etc. These situations will be evaluated on a case-by-case basis and the post and core should be placed with the greatest caution.
Tooth shows advance mobility. Mobility is an indicator of bone loss around the tooth and it should be evaluated on a dental X-ray as well.
When the tooth crown is severely damaged (especially when the tooth is fractured bellow the gumline) and the remaining part of the tooth is not strong enough to support the post.
dental abscess or tooth abscess
tooth with advance coronal destructions
Root canal preparation
The first objectives are to gain direct access to all root canals and round all corners and edges. Diamond or tungsten carbide burs at high or medium speed are used for this operation.
The dentist will then remove a part of the root canal filling from the canal space, usually by a series of specific endodontic files that prepare and shape the root canal.
After the preparation is completed, the space that exists inside the root canal, called the post space, is available to place the post. It is desirable to leave sufficient root filling material in the apical area to maintain an apical seal.
1. Post space
In post and core fabrication, it is desirable that the post descend at least two third of the length of the root canal, or not less than the height of the crown, in order to provide sufficient retention.
2. Apical seal
It is advisable to leave at least 4 mm of root canal filling at the apex of the root canal, even at the expense of a longer post. Within the last 4 mm of the root canal, the apical delta links the root canal with the exterior surface of the root.
The apical delta contains multiple small lateral canals. Should these lateral canals not be sealed with gutta-percha and other root filling materials, the chances of microleakage and percolation of microbes are greatly increased, thereby increasing the likelihood of an endodontic failure.
First, the length of each root canal is determined by analysing the data from the clinical examination and the x-rays. The depth of penetration is marked on each file with the help of a silicone stopper (or other kinds of markers).
The root canal is shaped by using progressively wider endodontic files at low or medium speed. Each file will penetrate the root canal at the predetermined depth.
root canal preparation
Sometimes, more than a single canal has to be prepared (in case of a device with two or three posts). The last file that is used will give the post space final dimensions.
From here on, the procedure differs depending on the type of post that is designed (prefabricated or cast). Prefabricated post and cores take less time to place while placing a cast post and core is a two-appointment process.
Last review and update: November 2020