3D‐Plotted Beta‐Tricalcium Phosphate Scaffolds with Smaller Pore Sizes Improve In Vivo Bone Regeneration and Biomechanical Properties in a Critical‐Sized Calvarial Defect Rat Model

Abstract

Due to the difficulty in fabricating bioceramic scaffolds with smaller pore sizes by the current 3D printing technique, the effect of smaller pore sizes (below 400 µm) of 3D printed bioceramic scaffolds on the bone regeneration and biomechanical behavior is never studied. Herein beta-tricalcium phosphate (β-TCP) scaffolds with interconnected smaller pores of three different sizes (100, 250, and 400 µm) are fabricated by 3D plotting. The resultant scaffolds are then implanted into rat critical-sized calvarial defects without any seeded cells. A custom-designed device is developed to investigate the biomechanical properties of the scaffolds after surgical implantation for 4, 8, and 12 weeks. The scaffolds with the 100 µm pore size are found to present the highest maximum load and stiffness, comparable to those of the autogenous bone, after being implanted for 12 weeks. Micro-computed tomography (micro-CT) and histological analysis further indicate that the scaffolds with the 100 µm pore size achieve the highest percentage of new bone ingrowth, which correlates to their best in vivo biomechanical properties. This study demonstrates that tailoring the pore size of β-TCP scaffolds to a smaller range by 3D-plotting can be a facile and efficient approach to enhanced bone regeneration and biomechanical behaviors in bone repair.

Reconsidering Osteoconduction in the Era of Additive Manufacturing

“…Here, scaf-folds with 0.10 mm channels performed better than more open channels. 94 Because the defect only had a depth of 0.5 mm, the animal study design might have favored the smaller channels.…”

Constructing a Sr2+-Substituted Surface Hydroxyapatite Hexagon-Like Microarray on 3D-Plotted Hydroxyapatite Scaffold to Regulate Osteogenic Differentiation

“…In the process of bone tissue repair, 3D interconnected macropore structures of the scaffolds are necessary for the delivery of nutrients and metabolic wastes, and is beneficial for cell growth and migration. We first prepared HA powder to develop a homogeneous paste with appropriate viscosity, and then fabricated the 3D-plotted HA porous scaffold with interconnected macropore structures [ 18 , 27 ]. As shown in Figure S1 , HA scaffolds with various structures (such as shape, size, and pore structure) were fabricated by 3D plotting.…”

“…For the application of bioceramic in bone tissue engineering, most studies have focused on controlling the crystal size [ 17 ], pore size [ 18 , 19 ], pore structure [ 5 , 20 ], porosity [ 21 , 22 ], and surface topography [ 23 , 24 ]. It was confirmed that bioceramic scaffolds with pore sizes > 200 µm are necessary to enhance bone formation [ 13 ].…”

Fabrication of porous carbonate apatite granules using microfiber and its histological evaluations in rabbit calvarial bone defects

“…Chang et al (Chang et al, 2000) reported bone ingrowth in the porous HAp implants with different pore sizes (50, 100, 300, and 500 μm) in the proximal tibia of rabbits and concluded that the 300-μm sized pores in the HAp implants were optimum. Diao et al (2018) by cell-cell contact. Moreover, infiltration of capillaries was observed in the porous HAp blocks with pore sizes more than 300 μm.…”

“…Taking these reports into consideration, a pore size ranging from 300 to 400 μm seems to be optimal for porous HAp. Diao et al (2018) by cell-cell contact. In short, smaller pore size provides narrower space for colonization and increases the opportunities for cell-cell contact, which facilitates osteoblastic differentiation.…”