Natural bone substitute intended to support bone growth in oral maxillofacial defects. Combined of bovine-derived, anorganic, cancellous bone-mineral granules and purified collagen fibers in a preshaped form. When placed into a bleeding site, the material expands to a predetermined size and shape. Expanding composite material allows for placement in a compressed form. Upon hydration/contact with blood, the material will self-expand to fill the entire defect. Composite nature of material enhances the graft stability, minimizes particulate migration, and optimizes spacing between particulate to allow for bone ingrowth.