Advanced imaging technique accelerates patient-specific 3D printing

bones of the foot, ankle and lower leg

Pioneering multidisciplinary research led by BHP founder member the University of Birmingham  has implemented an advanced imaging technique that could accelerate the development of patient-specific 3D printing used to regenerate long bone defects resulting from trauma or disease.

The University’s School of Dentistry and School of Metallurgy and Materials carried out the research in collaboration with the University of Manchester, Imperial College London, University College London, McGill University, Canada and Diamond Light Source. It has unravelled three important, never seen before, aspects of 3D printed scaffolds (used frequently in tissue regeneration), which could shape the development of clinical industry standards.

Using a bespoke high temperature furnace on a high-resolution 3D X-ray tomography beamline, the researchers successfully imaged and quantified, in real time, morphological changes occurring at both the global (struts that form the 3D scaffold) and local (individual glass particles that make up the struts) scales simultaneously.

Corresponding author Dr Gowsihan Poologasundarampillai, from the School Of Dentistry, explains: “We employed 4D tomography to capture morphological changes with sintering at high temperature of a 3D printed bioactive glass scaffold in real time, giving us a real insight into bioactive glass morphology.

“We hope that the insights we have provided through this research will give rise to the development of industry standards in developing 3D printed scaffolds for tissue regeneration.”

Bioglass® was the first material to form a stable chemical bond with human tissue. Since its discovery, a key goal was to produce 3D porous scaffolds which can host and guide tissue repair, in particular, regeneration of long bone defects resulting from trauma or disease.

Producing 3D scaffolds from bioactive glasses is challenging due to crystallisation events that occur while the glass particles densify at high temperatures. There is, currently, very little literature on viscous flow of bioactive glasses and none which focuses on the viscous flow sintering of glass scaffolds in 4D (3D + time).

This pioneering research explored the sintering mechanism of 3D printed bioactive glass tissue scaffold using synchrotron X-ray tomography. It was found that in 3D printed bioactive glass scaffolds, over 80% of all densification takes place in stage two where sintering is most rapid, however once pores become isolated at the end of stage two, whether they are removed with time depends on the morphology.

It is the first time that the three stages of sintering of glass particles in a 3D object have been observed and quantified, using an example of a 3D printed bioactive glass scaffold for bone regeneration.

The research, which was published in Materials Today Advances, will hopefully lead to further developments in printing for clinical use.