OK, I just got back from the store and bought some denture cleaning tabs.
I got the kind that is supposed to work in 15 minutes, and I soaked 4 penstyle and 4 510 attys that were really grungy for 30 minutes, then gave them a good fresh water rinse and Wow! They look like new again.
No gunk at all was left inside them. This by far is the best and easiest cleaning method I have ever tried.
Two thumbs up to false teethe.