Comparison of Selective Laser Melted Commercially Pure Titanium Sheet‐Based Triply Periodic Minimal Surfaces and Trabecular‐Like Strut‐Based Scaffolds for Tissue Engineering

Abstract

An opportunity is offered by porous structures as implants in medical applications and arthroplasties because their mechanical and physical properties can be tuned to match patient-specific needs. For ex vivo research, there is merit in using 3D models instead of 2D layers in tissue engineering to recapitulate cell growth in microenvironments that are similar to native tissue, because this narrows the gulf between in vitro tests and clinical translation. [1] Titanium and its alloys have been researched extensively because of their biocompatibility, high strength, low wear, and corrosion resistance (due to the passivating oxide layer spontaneously formed on the surface [2] ). When embodied as porous structures, they offer mechanical properties that can match those of cortical and trabecular bone, [3] avoiding stress shielding and biomechanical failure. Porous scaffolds must be conducive to osseointegration by means of providing channels and interconnected pores for nutrient distribution, [4] networks for cellular proliferation, differentiation and maturation, and ultimately for bone healing. [5] Much work has explored different pore architectures and sizes and routes by which they can be physically realized. Advances in computer-aided design (CAD), multiphysics modeling, [6] and additive manufacturing (AM) technology have allowed the definition of a design space to digitally test manufacturability boundaries for porous structures with the desired physical, mechanical, and permeability properties that can enhance biological behavior. [7] Techniques such as selective laser melting (SLM) or electron beam melting (EBM) have been demonstrated as practical processing routes to achieve both parametric and nonparametric designs, ordered or random, using metals. With regard to parametric designs, triply periodic minimal surface (TPMS) structures [8] have received attention in recent years as AM managed to realize the manufacture of these topologies that offer mechanical superiority due to a uniformly distributed load transfer, free of discontinuities and self-intersecting elements, and

Comparison of the design maps of TPMS based bone scaffolds using a computational modeling framework simultaneously considering various conditions

“…The surface-to-volume ratio of Gyroid structure at the porosity of 0.5 is approximately 3.0 mm −1 , which is close to the maximum value in the present study. 35 The surface-to-volume ratio of Schwarz P structure at the porosity of 0.5 is approximately 2.3 mm −1 , which is also within the range of the surface-to-volume ratio found in the present study. 36 Based on these comparisons, the design maps of elastic modulus and surface-to-volume ratio obtained in the present study are reasonable.…”

Surface Modification of Porous Titanium and Titanium Alloy Implants Manufactured by Selective Laser Melting: A Review

“…However, the unmelted powder particles inevitably adhere to the surfaces of SLM Ti and its alloy implants, especially for porous structures, resulting in excessive surface roughness, typically in the range of 5–40 μm, [ 114 ] and it can lead to a health hazard as the residual powder particles are dislodged from the implant surface and circulated into the body fluid. Figure shows the surface morphologies of SLM porous Ti and its alloys with various porous structures, including primitive, [ 115 ] diamond, [ 115 ] gyroid, [ 116 ] face‐centered cubic unit cell with vertical struts (F2CZZ), [ 117 ] body‐centered cubic (BCC), [ 118 ] and face‐centered cubic (FCC). [ 118 ] In addition, SLM Ti and its alloy implants encounter the issues of bioactivity, biological toxicity, antibacterial activity, corrosion, and wear resistance, as mentioned in Section 1.…”

Fiberglass‐reinforced triply periodic minimal surfaces (TPMS) lattice structures for energy absorption applications

“…12 Amongst the different lattice structures, triply periodic minimal surfaces (TPMS)-based lattices are gaining widespread attention as these structures exhibit higher load capacity and surface to volume ratio compared to strut-based lattice structures. 13,14 In addition, TPMS structures can be designed and optimized as per the requirements by varying the density, unit cell size, curvature, and periodicity. 15,16 Amongst the TPMS lattices, gyroid has been shown to possess exceptional mechanical properties compared to its counterparts as it has no reflectional symmetry nor straight lines leading to reduced stress concentration.…”

“…They offer tailorable properties such as energy absorption, 7,8 vibration mitigation, 9 thermal conductivity, 10 acoustic bandgaps, 11 and fluid permeability 12 . Amongst the different lattice structures, triply periodic minimal surfaces (TPMS)‐based lattices are gaining widespread attention as these structures exhibit higher load capacity and surface to volume ratio compared to strut‐based lattice structures 13,14 . In addition, TPMS structures can be designed and optimized as per the requirements by varying the density, unit cell size, curvature, and periodicity 15,16 .…”