Steven Manson, DDS PC
While a lot of times crowns and root canals do go hand-in-hand, it is best to think of root canals and crowns separately. For example, what is the reason I need a root canal and what is the reason that I need a crown. On a back tooth, the rule of thumb is that if a tooth is getting a root canal the best way to protect the tooth is by putting a crown on it. The logic here is simple. Back (posterior) teeth are used for chewing. Front (anterior) teeth are used for biting into things. This means that our back teeth get used much more often then our front teeth. The back teeth are also much more broad and flat then front teeth. After a root canal the hole in the center of the tooth gets filling up. It is usually best to hold everything together by putting a crown on top of the tooth.
As far as front teeth, the rule of thumb is quite the opposite. Since a front tooth is not used as much and the surface is smaller, it does not need a crown after a root canal. If the tooth is still intact then it might be better to leave it without a crown because the aesthetics will better match the rest of the front teeth. Or it can improve the aesthetics by doing a crown after the root canal if it was badly broken down.
So as 2 of the 3 situations described recommend a crown after a root canal it is very common; however, it is not always needed. Hope this helps.
My best to you!
William F. Scott IV, DMD