The technique of 3D printing is spreading rapidly in the field of medicine. Many hearing aids and dental crowns are now 3D-printed, as are disposable surgical instruments and even prosthetic limbs.
Additive manufacturing (AM), as the technique is also known, can even be used to make porous, melt-in-the-mouth pills for epileptics who are unable to swallow them.
Twenty-eight per cent of all medical technology and pharmaceutical companies have already used 3D printing, according to a recent survey of 12 mostly Western countries by the London-based professional services company Ernst & Young (EY).
Almost all hearing aids are 3D-printed these days, says EY manager Stefana Karevska, noting that while 3D printing is gaining ground across numerous industries, it has especially taken off in medical technology.
“It’s fascinating,” says Dr Bilal Al-Nawas, medical director of the Department of Oral, Maxillofacial and Plastic Surgery at Mainz University Medical Centre in Germany.
“Surgeons need 3D printing, and patients want it. Taking a piece of bone or tissue out of the body and then reinserting it somewhere else – that can’t be the future.”
In mid-May, Al-Nawas and his colleagues hosted the Second International Conference on 3D Printing in Medicine in Mainz, bringing together researchers, start-ups and 3D printer manufacturers from around the world.
One of the attendees was EOS, headquartered near Munich, a pioneer in the field of direct metal laser sintering and a provider of AM systems for plastics. Sintering is the process of turning a powdered material into a solid or porous mass by heating it – and usually also compressing it – without melting it.
One of the company’s 3D printers can make 400 individual dental crowns per day at a tenth of the conventional production cost, according to EOS manager Martin Bullemer, who adds: “Progress is being made throughout the entire field of orthopaedics.”
Screws aren’t 3D-printed, though, because lathes can make them faster. Researchers are currently concentrating on blood vessels, Al-Nawas says, pointing out that they have already been successfully implanted in animals.
“Blood vessels are the first step. If they work, a lot of other things are conceivable,” he adds, while also cautioning that whole organs such as livers and thyroid glands are probably still a long way off.
In 3D printing, a powder material such as titanium or plastic is fused by melting or sintering with a laser beam or infrared lamp, layer by layer. Since the layers are only hundredths of a millimetre thick, the process is extremely precise.
It’s even possible to make complex honeycomb-like structures that can’t be produced by drilling or injection moulding. The bespoke blueprint is created, for example, from a computed tomography scan.
Al-Nawas is working with a team of scientists on developing new materials that could be used instead of metal when it comes to reconstructing a face after a kick by a horse, for example.
“We would prefer a material that the body converts to bone, like magnesium. Or at least a material that’s more bone-like,” he says.
Researchers at Northwestern University in the US have 3D-printed bioprosthetic ovaries that restored fertility in infertile female mice.
After implantation, and without further treatment, the artificial ovaries ovulated, the egg cells were naturally inseminated and the mice gave birth to healthy pups, the team reported recently in the London-based scientific journal Nature.
Last year, US researchers described having successfully implanted 3D-printed cartilage and muscle tissue in rodents. The tissue formed blood vessels and nerve connections – a sticking point of 3D-printed body parts.
Printed body parts
In another development, the France-based NGO Handicap International has launched 3D-printing trials for 19 lower-leg amputees in Togo, Madagascar and Syria.
Using a small, lightweight 3D scanner to create a digital mould of the amputated limb, it then adapts the mould to the respective patient’s needs using computer-modelling software before sending it to a 3D printer. The printer produces a bespoke socket that corresponds perfectly to the shape of the amputated limb.
Al-Nawas cautions against overestimating the possibilities of this “exciting” new field of 3D-printed body parts, however, likening it to “slow boring through a thick board.” – dpa/Doreen Fiedler