I was told that older cats exhibit a behavior where they start pretty
much absorbing their own teeth. No one knows why, but as a result they
will start losing their teeth. Its quite painful for them. My poor
old cat (age 14) before I had to put him down was down to about 5
teeth. The vet said that his gums were in such pain that even when he
was under anestesia, they passed a finger over his gums and he had a
"shudder response" to the pain. I think the dental appointement is
well worth the money as cats will try to hide their pain so much your
poor cat may be suffering with bad teeth.

Good luck!