Liz Buchanan BVSc MRCVS
PPPS: with my apologies the the wretched organisation of this answer, I have realised that I have not included any possible diagnoses for you here. It is a feature of the programme that we cannot delete answers when we have written them - which is great for accountability, but not so good at times such as this. One possible explanation for what is going on in your cats' case, is gingival hyperplasia (overgrowth of the gums, often due to inflammation) but other, including more sinister causes may need to be ruled out. We hope that your vet is able to get to the bottom of it for you.