Teeth: Treatment vs. Quality of Life

My 9-year-old chin has been having more frequent dental issues and I am now considering . We've been doing floatings every few months lately, on top of Baytril & Metacam for cheek ulcers. His father passed away four years ago from health problems (dental, mostly) and his brother was put to sleep at only two years old due to dental issues. After this last floating (a week ago), he stopped eating on his own. We had been supplementing with Critical Care to get his weight up, but he wasn't even eating that when we brought him home. We took him back to the vet to be boarded, as the vet was having a better time getting his food and meds in. We also did dental x-rays.

He stayed the weekend and is now back home. The vet mentioned his upper molar roots are elongated, but thinks that there might be something else going on. They did full body x-rays, too, which were clean, but they want to do blood work. He had blood work about eight months ago and all was well, so I decided to hold off on that for now. He is not eating on his own still, and he is not taking his medicine well. He is keeping some CC down, but not really wanting to. I am waiting for a second opinion on his dental x-rays, but I wanted to see if you guys had any input.

This is my baby chin; I don't want him to suffer any longer, but I don't want to make a permanent decision if it is unnecessary. (When I asked the vet about the long-term, her solution was to keep him on pain meds.) I can attach the x-rays if it helps.