Evaluation of the Mechanical and Biological Properties of Polycaprolactone Scaffolds Produced by a Material Extrusion 3D Printer or 3D Pen: A Novel Bone Repair Strategy

Addressing the high cost and long cycle associated with the multistep digital restoration process involving 3D printing technology, we proposed the 3D pen as an innovative strategy for rapid bone repair. Capitalizing on the low melting point characteristic of polycaprolactone (PCL), we introduced, for the first time, the novel concept of directly constructing scaffolds at bone defect sites using 3D pens. In this in vitro study, we meticulously evaluated both the mechanical and biological properties of 3D pen-printed PCL scaffolds with six distinct textures: unidirectional (UNI) (0 degrees, 45 degrees, 90 degrees), bidirectional (BID) (-45 degrees/45 degrees, 0 degrees/90 degrees), and concentric (CON). The bone repair scaffold creation process was simulated using a fused deposition modeling (FDM) 3D printer and a 3D pen by creating a cattle bone defect model to compare the achieved scaffold time efficiency and accuracy. Mechanical test results revealed that 3D pen-printed scaffolds with different textures exhibited varying results in four tests, except the shear bond test. Optimal scaffold strength was consistently achieved when printing parallel to the applied force. Regarding biological properties, these scaffolds exhibited consistent cell viability over time and showcased excellent cell attachment capabilities overall. Furthermore, cells grew regularly along the printed filaments, with additional living cells at high elevations observed. Additionally, the 3D pen method outperformed traditional digital technology with an FDM 3D printer concerning accuracy and speed. These findings underscored the tremendous potential of the 3D pen in the realm of medical science, specifically within the domain of bone tissue engineering, characterized by its low cost, high speed, and convenience.