Providing enough stability for the dentist
After root-canal therapy the teeth need to be made good again.
If only a small amount of tooth structure has been removed teeth can be restored and conserved using bonded composites, sealing the inside of the tooth from bacteria. This also provides sufficient stability to enable the dentist to attach a crown.
Where much of the substance of the tooth has been lost, it may be necessary to insert a post for the crown to bond onto. A number of materials are possible: