Bone removal comes from where, if you need some before dental implants?

Human. We prefer to use sterilized human cadaver bone for implants. It provides an excellent solution and a high success rate.
Your bone is best. When your bone is used to add to an area where an implant is to be placed, where it comes from depends upon the amount needed. It can come from your chin, the back part of your lower jaw, your hip or your tibia. Whenever you need a bone graft, your own bone is best.
Many choices. Bone grafts for dental implants can be taken from your own body: chin, lower back jaw, hip and tibia (just below the knee). Most patients prefer bone from a different source and these options include: cadaver, bovine, synthetic and bone morphogenic protein.
Xenografts as well. One other option I did not see mentioned are xenografts, or grafts from another species. Bovine (cow) and porcine (pig) bone as well as some synthetic substances can also be used. While live bone from your own body is biologically an excellent choice, the obvious downside is that it requires a second surgical site from which to harvest the bone.
Hip, jaw and cadaver. There are several sources of bone. Transplants from the hip are common for large needs. Smaller areas can use bone from the jaw itself or cadaver bone. Consult with your oral surgeon as to the best type needed for your situation.
Two main sources. The patient body (donor site depend on the size of the bone), bone bank also available.