> "If we had a crystal ball and knew she was going to live to 100 it would be worth the implants."
Or not. Even if she lives that long or longer, the mental/physical trauma of going through all the appointments and procedures (benign as they are) and risk of infection with the multiple visits that will be necessary, are things that she doesn't need. The slightest thing going wrong when you're 91 could ruin what's left of her life. She'll be fine without that molar and the attachment on it. Those things are just food traps anyway and as I mentioned, I wouldn't be surprised if it wasn't the damage done to the anchor tooth by the contraption that's responsible for the problem in the first place.
> "Bad teeth can really affect the whole body, including the brain. It is not just a matter of a painful tooth."
Very true. If antibiotics don't knock out the infection in that molar you're talking about removing, then the tooth should be extracted. Persistent, low level infection in the mouth is not a good thing. It's a short trip from the infection site to the heart or lungs and will be a small but constant drain on her immune system. Eliminate the pathology is the priority here. An antibiotic could knock it out and if she's diligent with antiseptic mouth wash, you'll know in a couple months whether there's still infection. Meanwhile, take that bridge thing out of her mouth and put a crown on the molar if it can be salvaged. The bridge can be a source of gum irritation and in any case a major collector of bacteria. Bridges and root canals are 17th Century dentistry. If a tooth cannot be saved for whatever reason, an implant is the only intelligent procedure. Anything else (and dentists damn well know this) is just ADA "standard of care" money extraction.