I think I’ve solved it. Neighbours have put up a new bird feeder on the side of their garage so he’s hiding around the corner for the ground feeding birds. He’s eaten a pouch of gourmet and is chipper.
I was going to conjecture that you were being played. (For Gourmet etc etc.) Nonetheless, in humans, removing teeth can have an 'unsettling' effect on teeth left behind. I'd keep a close eye on his mouth - in conjunction with the vet. At 9, he's potentially coming up to having the lot out in three or four years time?