Andrew, did you have rheumatic fever at one time? I had it as a child, and for a long time some dentists required that I pre-medicate with an antibiotic before certain dental procedures, including cleanings (depending on what dentist I went to). They may have had me take the antibiotic after the procedure also, but I don't recall. I believe this was because rheumatic fever could cause heart valve problems (which you mentioned in this discussion).

Then a number of years ago (pre-OC), I was told this was not necessary. I even questioned a heart doctor about this, had some tests, and was told it wasn't necessary as they weren't any problems with my heart.

However, in recent years (post-OC) some dental professionals required pre-medication again. Manly for an extraction, but also a periodontist required it before a cleaning. This could be because of ORN danger, rheumatic fever, or both, but I was glad to use if as a precaution. Now my regular dentist does not required it for routine cleanings, but I'll use the Chlorhexidine (diluted) before and after a cleaning.

Wishing you the best!