It's BECAUSE OF the crowns needing to become installed that this is even an issue now. And when shaving down the tooth for the crown it was real close too. The enamel was starting to become less and less opaque because of how far downward into the occlusal surface (top surface) he had to shave off to be below the end of the compromised enamel from a cavity that formed there on the top amongst those folds on the tops of molar. This was also a molar that had the gum line held up against it very high up the side walls due to the wisdom tooth initially coming in impacted/sideways towards it. So at whatever age that was when Wisdom removed... there was already a compromised area below the altered gum line. Then one of the older style amalgam fillings developed a chipped-off piece from crunching on something hard eventually... and with the top and side compromised as it was, a crown was logical to do.
Also I had to have him grind a bit off the top of the crown because it was initially too tall after mounting so those teeth were meeting first before the others back there.
I've always bled like a stuck pig upon flossing. And I assume it's worse now due to BP meds with age. Just means I have to be on top of making sure I'm not leaving bits of meat in there. I also routinely swish with Hydrogen Peroxide at least once a day now. Seems to help with the tendency to bleed so easily in there.
If I'd have been later in addressing that one molar it'd have likely had to been a root canal done as well. But thankfully the compromised enamel stopped juuust shy of requiring he drill and break thru into the nerve-root space in there. Other than that troubled area back in there where there's no space and everything is tight... most everyplace else is fine and I don't even hardly get any build-up ever either.
So for now it is what it is and I'm happy to be able to leave it alone.