Abstract
The use of both bioglass (BG) and β tricalcium phosphate (β-TCP) for bone replacement applications has been studied extensively due to the materials’ high biocompatibility and ability to resorb when implanted in the body. 3D printing has been explored as a fast and versatile technique for the fabrication of porous bone scaffolds. This project investigates the effects of using different combinations of a composite BG and β-TCP powder for 3D printing of porous bone scaffolds. Porous 3D powder printed bone scaffolds of BG, β-TCP, 50/50 BG/β-TCP and 70/30 BG/β-TCP compositions were subject to a variety of characterization and biocompatibility tests. The porosity characteristics, surface roughness, mechanical strength, viability for cell proliferation, material cytotoxicity and in vitro bioactivity were assessed. The results show that the scaffolds can support osteoblast-like MG-63 cells growth both on the surface of and within the scaffold material and do not show alarming cytotoxicity; the porosity and surface characteristics of the scaffolds are appropriate. Of the two tested composite materials, the 70/30 BG/β-TCP scaffold proved to be superior in terms of biocompatibility and mechanical strength. The mechanical strength of the scaffolds makes them unsuitable for load bearing applications. However, they can be useful for other applications such as bone fillers.
Highlights
To tackle the complications associated with autograft and allograft methods, bone graft substitutes, known as bone scaffolds, were developed
A difference in weight was expected due to the difference in composition and the results reflect this; the density of bioglass is more than 10% lower than the density of β tricalcium phosphate (β-TCP), the scaffolds with a higher bioglass content were ~15% heavier than those with equal BG/β-TCP content
As the particle size of the powders was initially too large, it was necessary to mill the powder using grinding balls until the medium particle size was smaller than 2 μm and 90% of the grains were smaller than 5 μm diameter. This was suggested to improve the mechanical strength of the scaffolds [21]
Summary
To tackle the complications associated with autograft and allograft methods, bone graft substitutes, known as bone scaffolds, were developed. Synthetic bone scaffolds only possess, at most, two of the four ideal graft material characteristics; osteointegration and osteoconduction [1]. Materials 2018, 11, 13 a wide variety of challenges relating to the development of a successful graft material. Biocompatibility: The scaffold should be able to support normal cellular activity without inducing any local and systemic toxicity in the host tissue. Mechanical Properties: The mechanical properties of a bone scaffold should be similar to that of the host tissue it is replacing. Pore size: Scaffolds must have interconnected porosity for the supply of essential nutrients and oxygen, as well as bone tissue ingrowth. Bioresorbability: Scaffolds should be able to degrade in vivo, ideally at a rate similar to that of new tissue growth
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