A Smile like a Print

17. September 2008
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Researchers dream about a future when they could "print" skin tissue and blood vessels. Today the industry already expects promising market chances with laser-sinters of protheses, bones or dental protheses. This technology has the potential to revolutionize the manufacture of medical "spare parts" since it is faster, cheaper and extremely precise.

If powder is sintered respectively melted layer by layer by a focussed laser beam, we are talking about laser-sintering. If a print head functioning similar to an ink jet printer is used instead of a laser beam, it is called 3-D printing.
This layer manufacturing technology, also known as e-Manufacturing, Rapid Manufacturing (RM) or Rapid Prototyping (RP), revolutionizes now also the production of small- and smallest series. Originally RM or RP served to manufacture design models, prototypes respectively individual customized products fast and cost-efficient. Since the laser-sinter process works without expensive grinding- and milling machines, it can produce parts for a really competitive price compared to low-wage countries. If up to now a conventionally manufactured prototype cost USD 1,200, it could be USD 40 now if produced with RM. Related to dental protheses that might mean we no longer need dental crowns handmade in China.

Sinter-technology still lacks the right materials

Simplified just picture a laser-sinter system to be something like a black box, hardly ever larger than an XXL- refrigerator and fed with digital data. The results are for example knife handles, spare parts for airplanes, functional parts for a blood centrifuge, dental protheses or hearing aid shells. The box has to be fed with 3D geometry data, typically made with a CAD software. This 3D model is analyzed by a special data preparation software in the sinter system and dissected in down to hundredth millimeters thin layers which indirectly control the building up of the object to build. In this process pulverized materials are melted on layer by layer by a laser beam. Of advantage is that a variety of products can be produced with one machinery. The only limit up to now is the lack of suitable materials. Today mainly plastics, metals and foundry sand can be processed but new materials are added all the time. In particular for medical applications, EOS at Kraillingen near Munich expands its product range with cobalt-chrome alloys, premium steel mixtures, special plastics and titanium. And this paved the way for laser-sintered production of knee implants, dental protheses or hearing aid shells.

Laser-sintered orthesis at the Paralympics 2008?

Michael Teuber, paraplegic professional cycle racer, who wants to get gold at the Paralympics in Peking again, could get to the start with a laser-sintered orthesis for the first time. Preparations at EOS are in top gear. The right material for leg protheses and knee implants could be polyamides, i. e. plastics. On the plan of the people at Kraillingen is also the reconstruction of face bones with special metal alloys. As input for e-Maunfacturing, the laser-sinter system processes CAD-data, but also scan-data of a computed tomography. Depending on the model, costs vary at round about 19,000 Euro or more. Just how successful the laser-sinter technology will be established in this medical sector will continue to depend on the development of materials which fulfil the requirements regarding consistency, temperature stability and precision.

CAD/CAM-technology for dental protheses

The market for dental protheses turns out to be a bit simpler since it always showed trends for automation. With the implementation of CEREC (CEramic REConstruction) – the end of the nineties – the so-called dental CAD/CAM-technology gained ground. The system comprises an infrared camera and a milling machine grinding inlays, tooth crowns or veneers out of a raw block by calculated computer data. Today about 16,000 computer-aided CEREC devices, both labside and chairside, are operated worldwide, as the dental technician Josef Schweiger of the Arbeitsgruppe Keramik München (working group ceramics Munich) estimates. Purchase costs are between 45,000 and 75,000 Euro which might be the “knock-out” issue for most dental practices – although it sounds tempting if drilling, production of the dental prothesis and filling the hole can be done all in one treatment process.

Production facilities for 500 laser-sintered dental crowns a day

A significant disadvantage of CEREC is the loss of valuable material during the grinding- and milling process – something that does not happen with Rapid Manufacturing. On the other hand, a system like that costs about 250,000 Euro. For large production centers like Suntech, Bego and Sirona, the investment is still worthwhile. In 24 hours, a laser-sinter system can produce up to 500 frames for tooth crowns. With the conventional casting method, the average per day is ten crowns only. Allegedly the dental technician benefits from this development – according to EOS publications – because he or she has to concentrate only on the esthetic side of the prothesis. But can they live from that?

Ink-jet printer creates bio-sensors

At the chair in organic and macromolecular chemistry in Jena they are currently not printing any skin tissue or blood vessels yet, but "inkjet printing" plays a large role in research here. Joseph T. Delaney, doctoral candidate from Minnesota/USA participates in preparing the way there. "The general goal of my dissertation is the preparation of thin films with biomedical applications, mainly through inkjet printing", the researcher explains to DocCheck. "Since we can print so many materials, we can use inkjet printing to dispense things like drugs and polymers into patterns, and studying different formulations of drug delivery materials, for example. We can deposit immobilized enzymes and conductive lines to create biosensors."

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