3D printing: The transplant jaw
The idea of printing your own bones or body parts may sound like science fiction but it’s becoming more like just science. The process is unnervingly simple, take the object you want to create – break it down into 2D slices, print the slices, stick them together and the result is – just about whatever you want!
Last year in June an 83 year old woman from the Netherlands received a printed titanium jawbone implant after suffering from a chronic bone infection. Her age made reconstructive surgery risky so her doctors, in cooperation with Layerwise, a company which specialises in printing dental implants decided to recreate her jawbone.
Using an MRI of the patient’s jawbone to get a 3D template the printer then recreated the image complete with dimples and cavities to promote regrowth of muscle, and sleeves which allow for nerves to pass through. The titanium implant was then given a biocompatible coating. The technicians also printed support structures for the dental implants to follow. The implant itself is about 1/3 heavier than the the woman’s original jawbone but it has proved to be just as functional as her old. The woman’s doctors implanted the jawbone in June 2011 but have only revealed their experiences recently. Prior to this, 3D printing has been used to create thumb bones and the upper part of a man’s jaw.
To turn the slices into a composite part or object the printer moves the printed layers down by a fraction of a millimetre each printing round, slowly creating depth. The layers are then fused together by a laser. To make an 3D object you also need the right kind of ink, in this case technicians used titanium powder.
For each 1 mm of height approximately 33 layers of titanium powder were fused, but for all the thousands of layers which had to be printed the process took only a few hours.
The ability to create transplants which closely fit the individual patient’s physical needs, shorter surgery times and reduced hospital stays make the technology very attractive. This type of transplant may also have a longer lifespan due to the ability to create porous structures which help to facilitate bone ingrowth.
However strange it sounds it may soon be possible to fire up the printer and get a kidney!
Broadly speaking 3D printers vary in the technique they use to build layers and they come in three main categories summarised here.
Selective Layer Sintering (SLS)
How does it work?
Selective Layre Sintering uses a laser to fuse particles into a 3D mass. The particles pf powder are heated by the laser to melting point and fuse together. These use a wide range of ceramics, plastics, glass and metals.
What is it used for?
These create very complex geometric parts and this type of printing is typically end use manufacturing. Multiple parts can often be packed into the powder bed giving a high level of productivity.
Steriolithography
How does it work?
Steriolithography utilises a vat of UV curable resin and a UV laser – the laser traces a pattern on the resin, solidifying it and the tray descends by the layers’ thickness.
What is it used for?
Prototyping, models, patterns and sometimes production parts.
Fused Deposition Modelling
How does it work?
Liquid thermoplastics are deposited onto a platform following a path defined by the original model. Fine layers are built up when the platform descends. These machines use thermoplastics like ABS.
What is it used for?
Prototyping or rapid manufacturing.
If you had a 3D printer at home, , like a Thing-O-Matic you would be using FMD and ABS plastics. These printers are strong and relatively cheap in terms of both the machine and materials, however the resolution is limited and the control of texture is difficult. I asked Karen Marsh from Australian Network for Art and Technology (ANAT) if these “desktop” printers could print colour and she told me that although they can generally only use one colour filament at a time in printing acrylic paint afterwards works really well.
On the other end of the spectrum a company called Z-Corp have printers which can print in full colour in the machine itself. It uses powder and binder to make its layers and the colour comes from the binder. Objet also has a patented multi-material jetting technology that can print up to 14 materials in a single printing job. Objet also has printers which can print in layers only 28 microns thick to recreate objects in amazing detail. The SLS printers are what are used in stories like this one, about the woman who got a new jawbone!
By Robyn Lambert
Note: ANAT is currently developing a 3D printing program. Contact Karen Marsh for more information.
Related Content
View the event page – 3D printing: The next Industrial Revolution? (20 February 2012)
Read the blog post – Meet the 10 year old who loves his 3D printer by Freya Dougan-Whaite
