INNOVATIONS IN 3D PRINTED NANO-HYDROXYAPATITE SCAFFOLDS: A COMPARATIVE ANALYSIS OF PNEUMATIC AND THERMOPLASTIC EXTRUSION TECHNIQUES

Abstract

Abstract

Background: Complex maxillofacial, craniofacial, periodontal, and oral bone defects present significant challenges in reconstructive surgery. Traditional grafting techniques have set benchmarks, but bone tissue engineering offers promising alternatives. This study explores the fabrication of beta-tricalcium phosphate (β-TCP) scaffolds using pneumatic and thermoplastic extrusion techniques, evaluating their properties and compatibility with tissue engineering applications.

Methods: β-TCP scaffolds were fabricated using the Cellink BioX printer with pneumatic and thermoplastic extrusion heads. Inks were manufactured at Saveetha Dental College, and scaffolds were fabricated at IISc Bangalore. Key parameters, including extrusion temperature, pressure, feed rate, and nozzle diameter, were optimized. Printability was assessed by the number of layers achieved. The scaffolds were characterized using Scanning Electron Microscopy (SEM) and mechanical testing. Biocompatibility was evaluated using in vitro cell viability, proliferation, and differentiation assays with human mesenchymal stem cells (hMSCs).

Results: Thermoplastic extrusion achieved 7-8 layers per scaffold, compared to 3-4 layers with pneumatic extrusion, indicating superior printability. Thermoplastic scaffolds also exhibited higher mechanical strength with a Ultimate Tensile Strength of 51 MPa versus 35 MPa for pneumatic scaffolds (p ≈ 2.33×10−72.33 \times 10^{-7}2.33×10−7). SEM analysis showed regular pore structures (150-250 µm) and high interconnectivity in thermoplastic scaffolds, while pneumatic scaffolds had irregular pores (100-200 µm) and moderate interconnectivity. Additionally, thermoplastic scaffolds demonstrated better biocompatibility with higher cell viability (93.0% vs. 87.0%; p < 0.01), increased proliferation, and stronger differentiation markers.

Conclusion: Thermoplastic extrusion is more favorable for fabricating β-TCP scaffolds due to its superior mechanical properties, higher biocompatibility, and favorable microstructural characteristics. These findings support the use of thermoplastic extrusion for bone tissue engineering applications, with potential clinical implications for reconstructing bone defects in maxillofacial and craniofacial surgery, periodontal regeneration, and trauma repair.