I've asked a few doctors (and have had a few personal accounts as well) about this kind of thing and I'm still not sure I have a "good" answer for the question.
Thankfully, I had my wisdom teeth out long before I had any valve problems. I did have one other "bad" tooth out about a month or so before surgery but it was complication free. I ALWAYS take a prophylaxis (antibiotic, amoxicillin in my case) before seeing the dentist for anything. That's a precaution against endocarditis, an infection of the membrane that surrounds your heart, it can be deadly.
I've been to my dentist three times now since going on coumadin. I've asked him and my cardiologist about going off coumadin or taking an alternative before sitting in the chair and they've both said it wasn't neccesary. HOWEVER, I did bleed quite a lot after each visit, though the last time out (for a filling) wasn't as bad as the first two (a cleaning, that was REALLY messy, and a filling)
The only time I've ever bled that much in my mouth before was after having my wisdom teeth out and this time around was much worse.
It's really annoying, I HATED having a "spitoon" at hand at all times for a few days straight but it was neccesary when I had my wisdom teeth out and I had sworn I'd never do that again.
Guess what...
Grrr....
I've heard it from my dentist, my card, and my PP, no changes in your coumadin, it's not neccesary.
And I bled "profusely" for at least 12 hours after seeing my happy dentist, if not longer.
I may place a call to my surgeon in Cleveland next time I see the dentist, ask HIS opinion.