Deciding Post in the Root or Not - The decision to place a post in the root canal is based depending on the amount of tooth structure remaining above the gum line. If sufficient amount of tooth structure is present above the gum line and a small access cavity is present, then there is no need for placement of post. The tooth is just filled with a filling material and crown is placed over it if it is required.
But if large amount of tooth structure is missing above the gum line, a post has to be placed inside the root canal so that crown can be retained properly over it.
Procedure of Post and Core Placement
First of all, Root Canal Treatment (RCT) of the tooth is done to remove the infection and shape the root to receive a post. Use of local anesthesia is required while doing RCT. In root canal treatment; after cleaning and shaping the root, the root canal is filled with an inert material called gutta-percha to seal the root canal completely.
After the RCT is complete, in the subsequent appointment some of the gutta-percha from the root canal is removed leaving at least 5mm of gutta-percha inside the root canal. Then using a series of graduated instrument called reamer, root canal is enlarged sufficiently to receive a post.
Posts are usually pre-fabricated and available in many shapes. Post most suitable for the prepared root is chosen and cemented in the root canal such that it gets firmly embedded inside the root canal.
Placement of post in the root canal
The tooth structure is then built up using a suitable core material such as amalgam or composite. When core material gets hardened it is shaped properly and prepared to receive a crown.
Core build done over post
Then impression of the tooth is taken and sent to the dental laboratory for the fabrication of crown.
Until permanent crown gets prepared in the lab, the tooth is covered by a temporary crown for its protection.
Permanent crown is prepared in the lab in 10-15 days, so next appointment is scheduled accordingly and in next appointment permanent crown is cemented over core.
Crown cemented over core