Ceramics are a particularly interesting material in 3D printing, I think. When one thinks of ceramics, one typically thinks of china, pottery, coffee mugs, etc. The material is used in a much wider range of applications than most people realize, though, and the Ceramaker 3D printer has been demonstrating the versatility of ceramics while satisfying customers across multiple industries.
Developed by French company 3DCeram, the Ceramaker first caught our attention when it was displayed at Euromold last year. The printer utilizes pastes made from photopolymers combined with alumina, zirconia or hydroxypatite (HA), and 3DCeram is consistently working on developing new materials – they also offer custom formulations tailored to the needs of customers. Even without extra customization, though, the Ceramaker’s materials almost tailor themselves to a variety of applications in a number of industries.
For example, a ceramic paste made with alumina, aka aluminum oxide, is ideal for electronics thanks to its electrically insulating and conductive properties. It’s also hard and tough, making it a good abrasive or cutting tool. Zirconia, or zirconium dioxide, is a favorite of jewelers thanks to its high thermal stability and resistance to wear and chemicals, while hydroxypatite is similar to the substance of human bone, making it ideal for biocompatible implants.
3DCeram, in fact, has been working with 3D printed ceramics in the medical field for the last decade, since well before 3D printed implants ever crossed the mind of most people. The company has been working closely with Dr. Joël Brie and the maxillofacial surgery department at Limoges University Hospital on the development of cranial prostheses, and their hydroxypatite material has shown itself to be well-suited to the job, thanks to its osteoconductive and biocompatible properties that spur bone growth and allow the implants to integrate more easily and quickly into the body.
“Furthermore, an HA implant 3D printed with the Ceramaker has higher compressive mechanical strength than general HA used in synthetic bone graft,” said Key Liu, who manages quality and regulatory affairs at Taiwanese 3D printing service provider and reseller DETEKT. “These implants are an alternative to the osseous grafts that very often come from the patient, and thus HA implants can prevent them from experiencing additional pain. Ceramic implants are also well suited for reconstruction of bone defects, and the cosmetic result for the patient can be quite satisfactory.”
The Ceramaker operates with SLA technology, albeit with a few variations and additional steps. A thin layer of ceramic paste is laid down, and a laser hardens the photopolymers within the material. The print bed is lowered, and the process repeats until the print is finished, at which point the uncured paste is scraped away and reused. (That’s another nice thing about the Ceramaker; it’s pretty much zero waste since all of its materials can be reused and recycled.) Then the material is fired, debinding the polymers and sintering the ceramics.
Cranial prostheses are printed about 48 hours before firing, and thanks to the printer’s high resolution, the patient fit is just about perfect. That’s a bit more of a challenge than printing implants in other materials, because there’s shrinkage to deal with. The firing process results in about 20% material shrinkage, which means that superior CAD skills are needed to compensate and ensure the design of a perfectly-fitting prosthesis. When the design is done right, however, the Ceramaker can produce patient-specific implants with an accuracy of up to a tenth of a millimeter, according to Liu.
The material’s porosity further encourages fast bone growth; implants created with hydroxypatite are nearly 60% porous, and after six months, patients have shown bone regrowth over 25% of the porous areas. That’s remarkable. According to Dr. Brie, 17 patients have received 3D printed ceramic implants since 2005, when the hospital started using the technology, and none of them have shown any signs of infection. The implants are expensive, ranging from €10,000 (around $11,275) to €18,000 ($20,300), while the Ceramaker itself costs an impressive €290,000 ($327,000). For Dr. Brie and his patients, however, the cost is almost certainly worth it.
If you’d like to learn more about the hospital’s clinical trials of the 3D printed implants in 2013, you can check out the full study here. Discuss further in the 3D Printed Cranial Implants forum over at 3DPB.com.[Source: Engineering.com / Images: 3DCeram]