Bone regeneration using β-tricalcium phosphate (β-TCP) block with interconnected pores made by setting reaction of β-TCP granules

We fabricated an interconnected dual porous β-tricalcium phosphate (β-TCP) block via a setting reaction of β-TCP granules. This β-TCP block was unique because it exhibits a fully interconnected macroporous structure with micropores in the walls surrounding macropores and a roughened surface. The porosity and diametral tensile strength of the resulting product were 58.1 ± 1.7% and 1.4 ± 0.2 MPa, respectively. Rabbit distal femur bone defects were reconstructed using the porous β-TCP block and the efficacy of the porous β-TCP block as an artificial bone substitute was evaluated histomorphometrically. For a dense β-TCP control, 4 weeks following implantation, only 0.2 ± 0.1% of the β-TCP was resorbed, and the amount of newly formed bone was limited (0.1 ± 0.1%), whereas when the defect was reconstructed with porous β-TCP, 9.2 ± 3.1% was resorbed, and the amount of new bone was 18.9 ± 5.5%. This represents an approximately 50-fold enhancement in resorption and a 200-fold increase in bone formation for our porous β-TCP block. Therefore, interconnected dual porous β-TCP made via β-TCP granule setting has good potential as an artificial bone substitute.