I haven't had any dental work done while on Remicade or Imuran aside form cleanings. But I am a dentist, so maybe I'd be helpful? Typically, I premedicate within the AHA guidelines and in patients where there is a long standing, active infection or one that could potentially introduce bacteria in the bloodstream if they are severely immunosuppressed. I usually only predmed/post-medicate for really rough extractions or a long root canal. Premed usually for deep cleanings.
Personally, I only premed someone who is in our boat on high doses of a double immunosuppressants (like Remicade/Imuran or Humira/methotrexate). If they take that AND prednisone, they get premed with abs and Prednisone. Maybe I'm a little cavalier, but after being on these meds myself and reading up on them. Most times, the risk of an allergy to an antibiotic or a resistant strain of an organism is higher then the potential for infection.
Try not to worry about
getting dental work done. Some bacteria will be introduced into your bloodstream. It's normal during the procedure. Even immunosuppressed, your body will be able to fight them off with no problem to you. Restorations are very, very simple procedures with virtually no risk to you.
Hope that helps.