I’ve read about various kinds of key-tops available, some mimicking the look and feel of real ivory, and some said to be even better.
I have two older pianos that have the real, one piece ivories… my 1978 Yamaha C7 and my 1969 Kawai K48A upright. The key set on both are in good condition, but you can see some wear in the centers of the Yamaha key tops; you can’t really feel it, but if you look closely and at an angle, you can see some “cupping” in the center of the keys, like a wear spot. One key (D4) has a small chip on the edge. I like the looks and the feel of the key tops on both pianos.
Real ivory is harder to keep clean than plastic and seems to absorb the oils and dirt from your fingers more easily… no matter how clean they (hands and fingers) are. As far as keeping them white, you can clean and polish them, and, ironically, exposure to sunlight helps keep them white.
Here is a couple of pictures of my keyboard on the Yamaha after I cleaned and polished the ivories.Real, one-piece ivoires 1 Real, one-piece ivories 2
Good luck with you piano.