I need a root canal on my tooth with a 3 month old crown. I was told it was possible to drill on the top of the tooth, perform the root canal,and then put in a permanent filling. Can this be done safely in one appt.

Not usually. In my area, the endodontist will drill through the tooth and perform the root canal. If it's infected, it will take at least two visits. Once the root canal is completed, the endodontist sends the patient back to his family dentist to get the permanent filling.

I'd be interested in hearing about the drill through the crown procedure.

For now assume root canal on a normal tooth. Generally the root canal is preformed on all the roots and nothing bad happens during the procedure. Then the roots are medicated and temporary fillings are used. You then need to wait some time and see if any infection develops. If no infection, then permanent fillings are used.

Drilling through the crown only seems like a means to the end. I would expect the above be followed and then a new crown installed.
It may depend on the type of crown. With porcelin fused to metal things don't make sense.

In any event, you must make sure the root canal is stable. Those things hurt. Second most painful dental procedure. Crown lengthening is still #1.

It is not uncommon for a tooth to need a root canal after a crown is placed. The more a tooth is worked on increases the risk of the nerve dying and needing a root canal.

As to whether it is safe to do in one visit, depends on how infected the nerve is. If the tooth is in the early stages of dying and has very little infection at the root tips it definitely can be done in one visit. If there is a lot of infection (pus) at the root tips it may take at least 2 visits.

Root canals should be a painless procedure if you have good anaesthetic (freezing). When a tooth has a large area of infection it is difficult to get good freezing and the patient should be put on an antibiotic to reduce the infection before treatment begins.

Good luck

Yes it can be done and I had it done a few years ago with no problems.My dentist did it himself and it took 2 visits and a permanent filling was put in.

Yesterday I had a root canal done on #19 molar which has a crown. The endodontist drilled through the crown and put in a temporary filling. In 2 weeks I will go to my general dentist and have a post put in and then a permanent filling. There is no need, according to the endodontist to have a new crown. He said generally the crown is much sturdier than a tooth. I think unless your crown is damaged by the root canal; procedure, you should not have to pay for a new crown. If you do, maybe you should see a different dentist! A new crown in MA costs at least $1200. The post and filling only (lol) costs around $600.