I've noticed a blue/grey circle where my crowned tooth was filled after root canal. Is this normal? (Photo)

Without a picture it is difficult to determine the answer to your question without a picture. It is very possible to mask out the qrey caused by having a root canal. Also, a good dentist and lab should be able to accomplish this with only working on one tooth. The thing to know is that the tooth...

It would be acceptable to place a new temporary on the tooth at this point.  However, the final restoration, as you have been told, would need to wait until all healing has occurred, to make sure that the gum tissue does not change. 

I am sure that your dentist will make your permanent crown fit you teeth properly without a gap.  Let them know of your concern and they will take good care of you and give you a nice result.  Good luck!

Your best bet is to Redo the Dental crown and use a dental laboratory that does custom work.However, If for some unknown reason, you must keep the crown and do not want to remove it,You can also prepare the crown, as a veneer preparation, at this time, take an impression and order a customized...

Depending on how much of it is broken and what type of crown it is, it may be possible to repair it,at least temporarily, with composite bonding. The best and longest lasting solution is to have a new crown done unless you absolutely cannot afford to. Your dentist can give you the options...

I would have  conversation with your dentist and explain why you were unable to get back in to have the crown seated and that you have paid for it and would like to work out a way to get it finished. It sounds like the dentist may not have the crown any longer, so a new impression would...