Bone loss is likely due to infection - I had the same issue of bone loss in my jaw. Osteoporosis has many causes, and infection can be one of them, but generally the term is used for all-over bone loss and bone thinning not just one location. According to my dentist, you can rebuild the bone, but it is a slow process if it works at all. It means full calcium intake monitoring and also biting down on that tooth area consistently even if it hurts. But I don't know about if the tooth is missing or fractured. Good luck - you might want to go to a nutritionist to figure out if you are getting what you need for your teeth.