What is the benefit of drawing blood during a bone graft (GBR) procedure?

The blood drawn is spun in a centrifuge to produce CGF or PRF, concentrates rich in growth factors, for use in the bone graft. Because it comes from your own blood there is little concern about rejection, and mixed with graft material it 1) binds the particles together so they do not scatter, making surgery more precise, 2) supplies growth factors that help the gum and bone heal, and 3) may also help reduce swelling and discomfort after surgery. The amount drawn is small - less than for a blood donation - so the burden on your body is minimal.