Root canal treatment is not required prior to crowning a tooth.
Crowns are often done AFTER root canal treatment on back teeth to prevent the tooth from breaking during chewing. Teeth that require root canal treatment are usually severely damaged by decay or may be cracked. The extensive decay or crack compromises the strength and durability of the remaining tooth structure to withstand chewing forces over a long period of time. After root canal treatment, the tooth becomes less sensitive to excess pressure, so you may be able to bite on the tooth harder than if the nerve (pulp) were still intact. A crown will help to brace the remaining tooth structure better against these forces.
Pre-treatment x-rays are important to assess the likelihood of developing root canal problems after the tooth has been prepared for a crown. Your dentist can assess the amount of tooth structure covering the pulp and calculate if the amount of space required to fit the crown will risk exposing it.
To minimise the risk of pulp exposure, your dentist may advise choosing a metal/gold crown over a porcelain crown as metal crowns can be made thinner without compromising strength.
If a crown is planned for a tooth that needs to be realigned significantly ("instant" orthodontics), and orthodontic treatment is not going to be performed, then root canal treatment may be required. This is because the aggressive trimming of the tooth required to
- correct its alignment, and
- fit the chosen crown material may expose the pulp.
