alternative dental care for older cats

hi, i have two cats (DSH/DLH), both neutered males, one is 15 and one is 16. i know this is ignorant and mistaken, but for a long time i thought you weren’t supposed to brush cats’ teeth, so my cats have never had their teeth/gums cared for. i asked my vet whether starting now would help, and he said it would probably hurt them more than help them at this point, and explained that brushing their already-decaying teeth might cause them more pain.

i feel like there has to be something i can do besides let them suffer 😕 is there anything the lovely folks here can recommend? i understand that brushing may be too aggressive and harmful for their gums, is there maybe something they can chew on? anything that can maybe help preserve the teeth they have left?

please don’t shame me for not knowing i had to brush my cats’ teeth. i know it’s stupid, i know that my ignorance hurt my cats. i can’t change that. i’m trying to fix it now. thank you <3