What is it like getting a root canal on upper back tooth if tmj and limited ability to open? solutions?

Root canal with TMJ: If you need a root canal, then you need a root canal. The only alternative is extraction of the tooth. These days, with good local anesthesia, a root canal should be painless. If you can't open wide enough, it may be necessary to treat the TMJ problem first. This starts with finding out what the problem is and where it lies, whether in the muscles or the joint itself. This may require a TMJ mri.

Options: The dentist can give you a muscle relaxer pill to relax the muscles which will allow you to open wider with less strain during the appointment.

Might be impossible: See an endodontist. If he can't get access, you either have to see a TMJ doc to get you open wider, or have the tooth extracted.

Top docs!: While it is theoretically possible that if you can't open your jaw wide enough and\or the tooth presents with a difficult access and angulation issue, RCT might be impossible. You would then have to have the tooth removed. However, in 40 years of dental practice, I honestly can't remember not being able to resolve this issue. Discuss with an Endodontist and a dentist who treats TMJ\TMD issues.