I think I had four, two later extracted. Some were long before developing ME/CFS, some done, redone, or extracted after. No effect on ME/CFS symptoms.
The infection of a tooth could probably trigger ME/CFS, the same way other immune activation does, but removing the tooth afterwards is IMO, unlikely to help. ME/CFS seems to be something that gets triggered and then sustained by a feedback loop, so removing the trigger afterwards won't help...although I suppose it could possibly trigger a new ME/CFS event if you ever managed to cure the original one.