Well, color me surprised! I didn't think these things would matter which brand you bought, but it actually did!
I have rarely ever used these kinds of things over the decades of wearing dentures, and always just brushed my teeth - like everyone else, and that was fine. However, my new dentures got a dark spot, and I allowed the hygienist to scrape at it (Big Mistake), and now there are several grooves in my denture which trap food, and now turn black also - making it look as though I have cavities (Yeah, that's not cool!)
SO, I tried the no-name brand of denture tabs, and after going through an entire box of them - with very limited results, I ordered online, instead. My no-name brand wasn't available, so I took a shot on these. How delightful! These actually made a visible difference! I was stunned!
The black is not 100% gone yet, but it's wildly better than it was, and I'm hoping over time, it will go away entirely - or at least hold it at bay.
These were more expensive than the no-name brand, but they actually worked better. How surprising!