Interesting thread....I just found it.
There's been a lot of vitriol spewed between some of the people on this forum -- I was a favorite target a few years ago. I'm glad that this hasn't recurred -- so far.
A few of my personal insight:
Before my valve surgery 25 years ago, I had quite a bit of dental work done, and got the clearance for surgery.
One of my cardiologists a few years before the surgery wanted me to take antibiotics before any dental services - he prescribed gentamycin - an early generation antibiotic that has a long history of causing deafness in people who took it. Fortunately, that didn't happen to me, and since then, I haven't gone anywhere near gentamycin.
I haven't done a good job of my oral hygiene - years of laziness and never having gotten into the habit of brushing and flossing and the other stuff I'm supposed to do have made it hard for me to keep up a regular brushing regimen. (This failure to treat my teeth well resulted in a broken tooth this morning - I'll see if I can get it fixed before delaying too long).
My dentists have all required Amoxicillin before ANY procedure. In fact, some of the dentists keep it in their offices in case patients with a history of OHS come for treatment or exams. One dentist wrote a prescription for 20 tablets, so I'd be able to take them before my dental appointment.
I don't think that the issue is about killing gut flora. I think it's about knocking out the flood of bacteria that get into the bloodstream as a result of dental work. The antibiotics are usually a one time relatively high dose. The order of things like this goes: take antibiotics, release the nasty bacteria into the bloodstream where they all (it's hoped) get killed, go on with your life.
There's really no profit in manufacturing Amoxicillin - it's hard to believe that people would have it recommended to enrich the manufacturers of this low profit generic medication.