Hi and welcome to YT
. Glad you found us...wish it was under better circumstances for you and your kiddo.
Sadly, all of this is a reality of an aging dog. He could be confused as older dogs do get dementia, and this could be why he is peeing wherever. It's not his fault, really. As far as his teeth....honestly, if you're not going to have his teeth pulled, I would kindly euthanize him bc tooth infections are very, very painful and you don't want him to live with that kind of pain. Also, the infection will spread and could dig into the bone surrounding the area...the infection could also affect his heart very much.
I would really just assess his current quality of life and weigh that and discuss it with your significant other as to whether surgery is realistic at this point or not. Good luck and lots of puppy kisses to your elderly little fella...he sounds SO precious!