In vitro evaluation of novel composite bioceramic filaments for alveolar bone regeneration

Alveolar bone defect repair remains a major clinical challenge in oral and maxillofacial reconstruction. This study developed 3D-printable composite filaments combining polylactic acid (PLA) with bioceramic powders and evaluated their physicochemical properties and in vitro osteogenic potential for alveolar bone graft applications.

Filaments were fabricated via hot processing and tetrahydrofuran (THF) solvent casting, blending PLA with hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) at a 7:3 ratio. Four groups, H-PLA (heated PLA), H-MIX (heated PLA with HA/β-TCP), T-PLA (THF-processed PLA), and T-MIX (THF-processed PLA with HA/β-TCP) groups, underwent material characterization such as Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), scanning electron microscopy (SEM), and compressive strength testing, and MC3T3 cell-based assays for biocompatibility assessment.

H-MIX and T-MIX significantly enhanced compressive strength and osteogenic mineralization compared to PLA-only groups. HA/β-TCP was uniformly dispersed within the PLA matrix. Cell proliferation peaked on day 3, with both composite groups showing higher viability than controls (P < 0.01). Alkaline phosphatase (ALP) activity increased by day 7, with T-MIX significantly higher than H-PLA and T-PLA (P < 0.05). On day 14, T-MIX and H-MIX showed markedly greater mineralization, with T-MIX displaying the highest calcium deposition (P < 0.05 to P < 0.001).

Composite scaffolds made by thermal and solvent casting showed enhanced mechanical strength and osteogenic activity in vitro. T-MIX outperformed other groups in compressive strength, ALP activity, and calcium deposition. These results indicate that HA/β-TCP-reinforced PLA filaments, especially T-MIX, are promising for alveolar bone repair.