Can you have a root canal done through a crown by drilling and refilling?

Some times a crown can be removed before doing a root canal, but generally not. It is standard procedure that if the dentist/endodontist could not remove the crown to drill a hole through the top of back teeth, or back of front teeth, and do the root canal through the hole. Then fill the hole by placing a core and/or filling. Is the crown compromised? Possibly. If a porcelain crown it will be weaker.But, saying that, how would you feel if your dentist aggressively tried to remove the crown and in the process broke you tooth and you then had to have it extracted (pulled), and the space where the tooth was replaced with an implant or bridge. The down side of that scenario is much worse than the compromise of the endodontist drilling a hole in the top of the tooth and then filling it.

If your crown is OK and margins, contours, contacts are acceptable, root canal can be done through the crown. It has to be evaluated by your dentist.

If the crown was fairly new, and was not compromised much from decay, then, yes, it can be done. There is no 100% correct answer. It is a judgement call by an experienced dentist.