Bob
I know you’re big on adjusting occlusion with LPT so I know that is done. The fill is short and I would retreat now that the bone is filling, and I’d try the LPT again. There does look to me that there may be a fracture at the level of the tip of the post. I think the idea of removing the pontics and doing implants sounds good. Sure looks like that tooth is overloaded.
I’ve been having great success with some very shaky 9+ pockets that are shrinking up fantasticly after Periolasing. It seems to sterilize the pockets very well and I find I get more irritation with antibiotics in the pocket than not.
Good luck and see you in a few weeks.