New crown first then root canal?

I suggest calling your endodontist and ask for further clarification as to what he is advising and the order in which he is suggesting. My guess is that you misunderstood and/or he miscommunicated. Almost always, the root canal will be done prior to placing a new crown. However, he may be suggesting "a temporary" crown before he does the root canal. That makes sense.

Hi Mike...I think there is some miscommunication between the doctor and patient. I think what the doctor is trying to say is he will take off the old crowns and do the retreat and the new root canal and place temporaries on them until the new crowns are made. He will not drill holes in the new crowns to do the root canals.

Most of the time, the root canal is done first, then the crown is redone. This prevents you from drilling thru a new crown that will posibly lead to porcelain fracture or micro leakage in the future. I'm not sure why your endodontist would want to do it like this. He is correct in wanting the old crowns out and the decay removed. But if he wants it done prior to the root canal, your dentist can put you in a temporary crown that your endodontist can remove to complete your root canal. This would allow him better access and would avoid senseless destruction of your new crown.