After a rootcanal do i need a crown?

Usually needs crown: If the tooth needed root canal therapy, chances are it's broken down pretty bad. A filling just may not be enough. Teeth become brittle after root canal therapy, too, so they tend to break a bit more easily. Discuss this with your dentist.

Get it fixed: The most common cause for root canal failure is new infection leaking in. When a tooth is not restored this avenue for reinfection is of major concern. Literature written about this subject suggests reinfection can occur in just 30 days ! i strongly suggest you revisit your dentist to be sure it hasn't already occurred. If the seal is still intact "get it fixed".

Root canal: Crown: Yes .Root canal therapy removes dead infected tissues from teeth. The tissue (blood vessels) when alive help the tooth supple and flexible. When there is now no blood supply the tooth dehydrates and become brittle. Molars, your back teeth, crush with hundreds of pounds of force. That can easily break a tooth. Crowns protect the tooth from that force.