Additive Manufacturing of Bone Scaffolds Using PolyJet and Stereolithography Techniques

Shummaila Rasheed,Muhannad Obeidi,Waqas Lughmani,Inam Ahad,Dermot Brabazon

doi:10.3390/app11167336

Abstract

In this study, the printing capability of two different additive manufacturing (3D printing) techniques, namely PolyJet and micro-stereolithography (µSLA), are investigated regarding the fabrication of bone scaffolds. The 3D-printed scaffold structures are used as supports in replacing and repairing fractured bone tissue. Printed bone scaffolds with complex structures produced using additive manufacturing technology can mimic the mechanical properties of natural human bone, providing lightweight structures with modifiable porosity levels. In this study, 3D scaffold structures are designed with different combinations of architectural parameters. The dimensional accuracy, permeability, and mechanical properties of complex 3D-printed scaffold structures are analyzed to compare the advantages and drawbacks associated with the two techniques. The fluid flow rates through the 3D-printed scaffold structures are measured and Darcy’s law is applied to calculate the experimentally measured permeability. The Kozeny–Carman equation is applied for theoretical calculation of permeability. Compression tests were performed on the printed samples to observe the effects of the printing techniques on the mechanical properties of the 3D-printed scaffold structures. The effect of the printing direction on the mechanical properties of the 3D-printed scaffold structures is also analyzed. The scaffold structures printed with the µSLA printer demonstrate higher permeability and mechanical properties as compared to those printed using the PolyJet technique. It is demonstrated that both the µSLA and PolyJet printing techniques can be used to print 3D scaffold structures with controlled porosity levels, providing permeability in a similar range to human bone.

Highlights

Natural human bones have characteristics that allow them to regenerate and heal naturally, these characteristics are often not effective for large bone defects and injuries resulting from tumor resections, old age, and traffic accidents
This research showed that microstereolithography is more precise than the PolyJet technique when printing complex shapes, there was not a big difference between the permeability and mechanical strength values of the scaffold structures printed using both techniques; the microstereolithography method took more time to print a single scaffold structure with a limited scaffold size and geometry
With the PolyJet technique, multiple scaffold structures could be printed in a short time with a large range of sizes based on the build area

Summary

Introduction

Natural human bones have characteristics that allow them to regenerate and heal naturally, these characteristics are often not effective for large bone defects and injuries resulting from tumor resections, old age, and traffic accidents. These challenges in orthopedics pose significant risks to the health and quality of life of individuals [1,2]. In comparison with natural bone grafts, synthetic materials have drawbacks, including the manufacturability of complex structures [8], uncontrolled permeability [9], unmatched mechanical properties, high density (for metals), ion release from metals [10], the friability of ceramics [11], the low strength of polymers [12], and the uncontrollable degradation of composites [13]; smart nanoparticle-based composite materials can be used to control the degradation rate [7]

Methods

Results

Conclusion