I lost my four bottom front teeth to root resorption. Didn't have anything to do with. Hadn't been diagnosed with osteopenia at that time, and I wasn't on any of the meds. Dentist says it just happens - there are theories, but mostly the reason for it is unknown. Dentist sent me to endodontist just to see if root canals might save the teeth. Endodontist told me it would be a waste of time and money - I would lose the teeth anyway. I now have two implants and an implant bridge.