We fetched him last night!
He had the dental surgery yesterday, and the vet removed his top two canines! My Greebo has always had the tips of his top two canines peeking out from under his top lip and now they're gone!
The other teeth got cleaned but were not loose so the vet left them in. What he did find though, is that his gums are receding quite badly, which makes his teeth very sensitive.
This can partially explain his grumpiness, but old age can also be a contributor to that. We'll see how he manages with food as his teeth may be too sensitive to manage dry food and he'll have to be fed soft food from now on.
So far so good, he ate some soft food when he got home and this morning he was eating dry food, we just need to watch him to make sure he's getting enough food.