Design and evaluation of anisotropic octet-truss scaffolds for mimicking the mechanical behavior of human jawbone.

The human jawbone exhibits anisotropic mechanical behavior due to its complex trabecular microstructure, creating challenges for bioinspired scaffold design in maxillofacial implants. In this study, anisotropic scaffolds were fabricated from PolyLactic Acid (PLA) using Fused Deposition Modeling (FDM) and based on modified octet-truss unit cells. Geometric anisotropy was introduced by stretching the unit cell in one direction, generating configurations with varied cell sizes and stretch ratios while maintaining constant scaffold volume. Quasi-static compression tests characterized Young's modulus and yield strength in longitudinal and transverse orientations. Directional elongation significantly influenced anisotropy, with structures of larger unit cell size and moderate stretch ratio (e.g., 1.5 stretch with 9 mm cell size) closely approximating mandibular trabecular bone. These scaffolds achieved anisotropy ratios exceeding 2.5 between principal directions, while density values remained within the physiological jawbone range. Beyond mechanics, the immune response is equally decisive. Although PLA is widely used for its printability and biocompatibility, its degradation may acidify the microenvironment and favor pro-inflammatory macrophage activation. Strategies such as incorporating hydroxyapatite, bioactive coatings, or chemical modifiers can promote M2 polarization, enhancing angiogenesis and bone repair. Thus, the proposed scaffolds unite mechanical fidelity with immune-instructive potential for mandibular regeneration.