Microwave-sintered 3D printed tricalcium phosphate scaffolds for bone tissue engineering

This study reports the manufacturing process of 3D interconnected macroporous tricalcium phosphate (TCP) scaffolds with controlled internal architecture by direct 3D printing (3DP), and high mechanical strength obtained by microwave sintering. TCP scaffolds with 27%, 35% and 41% designed macroporosity with pore sizes of 500m, 750m and 1000m, respectively, were manufactured by direct 3DP. These scaffolds were then sintered at 1150 degrees C and 1250 degrees C in conventional electric muffle and microwave furnaces, respectively. Total open porosity between 42% and 63% was obtained in the sintered scaffolds due to the presence of intrinsic micropores along with designed pores. A significant increase in compressive strength between 46% and 69% was achieved by microwave compared to conventional sintering as a result of efficient densification. Maximum compressive strengths of 10.95 +/- 1.28MPa and 6.62 +/- 0.67MPa were achieved for scaffolds with 500m designed pores ( 400m after sintering) sintered in microwave and conventional furnaces, respectively. An increase in cell density with a decrease in macropore size was observed during in vitro cell-material interactions using human osteoblast cells. Histomorphological analysis revealed that the presence of both micro- and macropores facilitated osteoid-like new bone formation when tested in femoral defects of Sprague-Dawley rats. Our results show that bioresorbable 3D-printed TCP scaffolds have great potential in tissue engineering applications for bone tissue repair and regeneration. Copyright (c) 2012 John Wiley & Sons, Ltd.