My daughters were both made to stop their biologics but that is now considered unnecessary (this was years ago - M was 15 and S was 18). Since they stopped their biologics, both flared (arthritis flares, not IBD - M was not diagnosed with IBD yet).
S was sedated for her wisdom teeth extraction - she was given Versed and Fentanyl I think and doesn't really remember anything. She was told to stop NSAIDs to minimize bleeding, so took Vicodin for 5-6 days.
M was not sedated for her wisdom teeth extraction - she and the oral surgeon thought she could "tough it out." I was pushing for sedation, but ultimately let her decide. She did well - it was a LOT of numbing injections (she stopped counting after 10) and she said she was surprised by how much force it took to pull out her teeth (some of hers were impacted, so she did have dissolvable stitches).
But it did scare her a bit, because she fainted right after they were done and in retrospect, she says she wishes she had been given a little sedation (every single one of her friends that had their wisdom teeth out was given IV sedation and they were asleep or do not remember their surgeries).
She was given Tylenol with Codeine but that wasn't enough to control her pain, so she was then put on Vicodin for around 4 days and after that she took extra strength Tylenol. She was also told to stop NSAIDs, though again, I'm not sure that was necessary.
They both healed well, without any issues. They were allowed to re-start their biologics about 10 days after surgery and honestly, both of them had pretty bad arthritis flares. We do know plenty of kids with juvenile arthritis who had their wisdom teeth out while on biologics and healed well (and avoided a flare)! But one of my daughters had a friend with Crohn's who had her wisdom teeth out while on Prednisone - that was a bad idea and hers got infected.
For both girls, day 3 was when the swelling was the worst. Ice cream helped
. And for both, the oral surgeon talked to their rheumatologists, so it would probably be good for your son's GI to talk to his oral surgeon, especially if he is on steroids.