I know two people who have had this done and I guess I just do not understand it. The two people I know could not be more different, age is not an issue, family genes as far as either know, etc. Why is this normally done?
It all depends on which part of the body needs the bone graft. Are you referring to dental grafts? With dental grafts, they are done to build up the area of the jaw. Once a tooth is lost, bone is also lost in the area. There isn't enough of a ridge of bone there for crowns to be inserted or for dentures to sit properly.
Yes these were both dental related, sorry about that. My half sister had this done when she was about 20 and the young man I know who is barely old enough to drink beer had this before he even completed high school. Is there something genetic that causes this issue?
If you look at a picture of the human skull, you'll see there really isn't a lot of bone there once the tooth is gone. After the root is removed there is a hollow area. Genetics certainly play a role in the way the jaw is shaped and whether we inherit good, strong teeth.
After some of the dental work I have had I am amazed at how much we never really see. It seems there is an extra area of bone on my bottom jaw, so where a friend of mine has too little I have too much.