know I'm getting old in the tooth
 

I bought some insulated leather boots nearly twenty years ago.
I just "wore" the leather out of those boots. Still fairly great after some six years, I started seeing hunters had problems with the new ones and decided to wait. I hadn't had trouble with leaking and excessive wear. So I waited; I waited; I waited. And I continued to wait.

Just saw a post from this year. Leaking of the boots and excessive sole wear. I'm over waiting and wonder who bought all the leaking boots .
I just got old waiting for those boots to get better, which they never did.

While I have no doubt that your teeth are indeed old, it's "Long in the tooth"... In reference to a horses' teeth that never stop growing, hence at an old age, their teeth grow quite long...