Porous ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. Solid free form (SFF) fabrication methods allow fabrication of ceramic scaffolds with fully controlled pore architecture, which opens new perspectives in bone tissue regeneration materials. However, little experimentation has been performed about real biological properties and possible applications of SFF designed 3D ceramic scaffolds. Thus, here the biological properties of a specific SFF scaffold are evaluated first, both in vitro and in vivo, and later scaffolds are also implanted in pig maxillary defect, which is a model for a possible application in maxillofacial surgery. In vitro results show good biocompatibility of the scaffolds, promoting cell ingrowth. In vivo results indicate that material on its own conducts surrounding tissue and allow cell ingrowth, thanks to the designed pore size. Additional osteoinductive properties were obtained with BMP-2, which was loaded on scaffolds, and optimal bone formation was observed in pig implantation model. Collectively, data show that SFF scaffolds have real application possibilities for bone tissue engineering purposes, with the main advantage of being fully customizable 3D structures.

The influence of polymer infiltration on the flexural strength and toughness of β-tricalcium phosphate (β-TCP) scaffolds fabricated by robocasting (direct-write assembly) is analyzed. Porous structures consisting of a tetragonal three-dimensional lattice of interpenetrating rods were impregnated with biodegradable polymers (poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL)) by immersion of the structure in a polymer melt. Infiltration increased the flexural strength of these model scaffolds by a factor of 5 (PCL) or 22 (PLA), an enhancement considerably greater than that reported for compression strength of analogue materials. The greater strength improvement in bending was attributed to a more effective transfer of stress to the polymer under this solicitation since the degree of strengthening associated to the sealing of precursor flaws in the ceramic rod surfaces should remain unaltered. Impregnation with either polymer also improved further than in compression the fracture energy of the scaffolds (by more than two orders of magnitude). This increase is associated to the extraordinary strengthening provided by impregnation and to a crack bridging toughening mechanism produced by polymer fibrils.