There are four classes of bone-grafting materials based upon the mode of action:
i. Autografts: Autogenous bone (usually harvested from mandibular ramus and chin) is an organic material and forms bone by osteogenesis, osteoinduction, and osteoconduction.
ii. Allografts: Graft tissues such as demineralized freeze-dried bone are osteo-inductive and osteoconductive and may be cortical and/or trabecular in nature. Allograft is derived from humans and is harvested from an individual other than the one receiving the graft.