"My dentist told me not to take I think it might be Alendronate aka Fosamax because she said it can cause osteonecrosis of the jaw. "

This is true. My brother is a periodontist. He advised both me and my mother who's in her 80s not to take it. She didn't take his advice. She was on Fosamax and also Prolia for a couple of years and has had major dental work. Currently, she has a big problem with a cracked tooth and broken crown. She was hoping to get an implant. But a CT scan showed her jaw is too weak to support one.

I myself have osteopenia, bordering on osteoporosis in my right femur and hip. My endocrinologist has been after me to take Fosamax. Between dealing with side effects from other meds and a Prednisone taper in process AND needing major dental work in the coming months, I've decided not to take it. I might reconsider at some point, but right now I can't see taking it.