Freeze extrusion fabrication of 13-93 bioactive glass scaffolds for bone repair

A solid freeform fabrication technique, freeze extrusion fabrication (FEF), was investigated for the creation of three-dimensional bioactive glass (13-93) scaffolds with pre-designed porosity and pore architecture. An aqueous mixture of bioactive glass particles and polymeric additives with a paste-like consistency was extruded through a narrow nozzle, and deposited layer-by-layer in a cold environment according to a computer-aided design (CAD) file. Following sublimation of the ice in a freeze dryer, the construct was heated according to a controlled schedule to burn out the polymeric additives (below similar to 500A degrees C), and to densify the glass phase at higher temperature (1 h at 700A degrees C). The sintered scaffolds had a grid-like microstructure of interconnected pores, with a porosity of similar to 50%, pore width of similar to 300 mu m, and dense glass filaments (struts) with a diameter or width of similar to 300 mu m. The scaffolds showed an elastic response during mechanical testing in compression, with an average compressive strength of 140 MPa and an elastic modulus of 5-6 GPa, comparable to the values for human cortical bone. These bioactive glass scaffolds created by the FEF method could have potential application in the repair of load-bearing bones.