['An experimental study of rabbit calvaria evaluated the suitability of porous beta-tricalcium phosphate (beta-TCP) block as a biomaterial for onlay bone grafting and determined whether the addition of platelet-rich plasma (PRP) can accelerate bone formation inside the pores of the beta-TCP block.', 'In eight rabbits, the calvarium was exposed, and the marrow was penetrated. The beta-TCP blocks were made of Ca3(CO4)3 (porosity, 75%; diameter, 8 mm; thickness, 5 mm). For the experimental group, the blocks were treated with PRP; for the control group, the blocks were treated with venous blood only. Each block was placed in the bone, attached with a titanium screw, and covered with a cutaneous flap. The animals were sacrificed after 3 months, and the tissue ingrowth into the blocks was euthanized.', 'Histologic and histomorphometric measurements demonstrated that there was no inflammatory infiltration around the blocks in either group. New bone formation inside the blocks originated from the parent bone in both groups. The mineralized bone generated tended to climb along the inner walls of the block. In addition, mineralized bone formation was noted around the titanium screw. Furthermore, there was no significant difference between the experimental and control groups in the relative amounts of newly generated tissue and mineralized bone generated in the blocks.'] Does the use of porous beta-tricalcium phosphate block with platelet-rich plasma as an onlay bone graft biomaterial?