Cats can get decayed teeth...some breeds are prone to tooth problems, such as Oriental Shorthairs.
My mom has my late sister's two lilac points, and they have just several teeth left each!
Please get a second opinion on your cat - maybe a friendly vet can show you where the decay is - if there is any - so you don't have to just take someone's word for it.
"You can say any foolish thing to a dog, and the dog will give you a look that says, 'Wow, you're right! I never would've thought of that!'" -- Dave Barry