ASSESSMENT OF IN VITRO DEGRADATION OF 3D BIOREABSORBABLE SCAFFOLDS FOR BONE REGENERATION

Introduction: Bone regeneration using bioresorbable scaffolds requires understanding their degradation mechanisms. This study evaluates the effect of filler content on microstructure and mechanical properties during in vitro degradation. Three-dimensional printing enables the fabrication of complex geometries that mimic natural bone architecture and patient anatomy. Polymers such as PHBV (polyhydroxybutyrate-co-hydroxyvalerate) are widely studied due to their biocompatibility, biodegradability (∼ 2 years), and mechanical properties (0.2 - 1.5 GPa) comparable to trabecular bone. PHBV combined with bioactive glasses (BGs) can result in composites with enhanced stiffness, hydroxyapatite formation, and osteoconductive properties.

Methods: In vitro degradation experiments were conducted to evaluate structural changes in polymeric composites with BGs of different reactivity. PHBV and PHBV + BG (2 and 4 wt%, 1393 and 45S5 compositions) filaments were produced by extrusion and 3D-printed. Scaffolds were immersed in simulated body fluid for 30 days. Before and after soaking, scaffolds were characterized by microcomputed tomography, scanning electron microscopy, X-ray diffraction (SAXS-WAXS), and weight loss and swelling measurements. Mechanical behaviour was tested under bending and compression.

Results: Scaffolds showed good adhesion between layers, a smooth surface, and interconnected pores with pore size that promotes osteogenesis (100–500 μm). BG particles significantly enhanced the bioactivity of the composite, leading to the formation of a hydroxyapatite-like layer on the surface. 3D-printed rasters exhibited a porous internal structure, a sign of internal degradation. After 30 days, PHBV-BG composites exhibited weight loss and swelling below 1.5%. Mechanical tests confirmed the structural integrity of the fabricated scaffolds. Degradation decreased the maximum strength (12 MPa vs 4 MPa at 30 days), elongation at break (4% vs 3% at 30 days) and the elastic modulus (600 MPa vs 300 MPa at 30 days).

Conclusions: This study demonstrates that bioactive glass particles influence degradation kinetics in polymer–bioactive glass composites, with potential applications in bone regeneration.