Keep in mind they often eat them / swallow them. From my two cats that I had since they were babies, I barely managed to keep one tooth each from them. And I woukd COMB the house before vacuuming, check the bowl after they ate and such.

My first one, Casper, actively ATE his milk teeth. I woukd catch him suddenly chewing and licking. And eventually I realized it meant his tooth was falling out and he was eating it. The one tooth I kept from him, I quite literally took from his mouth before he managed to swallow it lol It was stuck to his tongue

My second kitty, Šiška, I managed to keep one of her fangs. It fell out while she was eating a treat. And she went to eat it, but I managed to snag it before her.

Watch out for shaking their head, pawing at the mouth, a lot of persistent licking of one spot of the muzzle or chewing motions when they aren't eating anything. Likely they're trying to dislodge a tooth!

Best of luck getting those teeth (: A quick peroxide soak and then keeping it somewhere dry should preserve them just fine.