If I've already had a root canal and my crown falls out, will it hurt anything to just leave it out?

Hi:If you do not get the crown recemented, you bite could change, tooth may get decayed over time and your crown may not fit.  It is best to get the crown recemented as soon as possible.Best,Dr. Maddahi

Hello and thank you for your question. The best way to answer this is with an in-person evaluation. However, I don't recommend leaving the crown off. I recommend getting a consultation with a Prosthodontist, who can discuss with you the different options.  A Prosthodontist is a dental specialist who has advanced training in restoring teeth and can create a customized treatment using the latest techniques in restoration.

Your crown should not have fallen off a root canal tooth.
The questions that should be answered is why did the crown come off? Does the crown fit back on the root canal tooth or is their decay or is the tooth fractured. You should return to your dentist to evaluate the problem and if there is no caries or fracture, then the dentist should re-cement the crown.
Leaving the crown off will eventually cause you to lose the tooth.