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Tag 3D Printed Jaw

3d printing techniques for Dental products

The dental industry requires custom-part, single-unit production, with excellent accuracy. Therefore, dentistry is getting more and more attention in the 3D printing industrie . Additive manufacturing equipment makers and material suppliers for these printers are already taking notice.

Currently, 3D printing technology is used to provide a number of products in the dental industry. Most common are wax patterns for fixed prosthodontics and models fabricated from intraoral or impression scans. However, popularity is gaining for orthodontics and removable prosthodontics.

There are basically 5 different 3D printing technologies being used in the dental industry today: Digital Light Projection (DLP), Jet, Stereo-Lithography Apparatus (SLA),Selective Laser Sintering and Direct Laser Metal Sintering (DLMS). Each system varies in the materials available, how those materials are solidified, and how they can be used.

 

Digital Light Projection (DLP) 3D printing



The working material for Digital Light Projection is UV- and visible-light sensitive and held in a reservoir. A wiper blade spreads material uniformly across the build platform after each layer is printed. DLP then takes advantage of the same technology used in certain television sets and presentation projectors to illuminate the outline of all of the parts simultaneously. The printed material is cured using a lamp or LED light source depending on printer model.

Typical vertical resolution is 13 µm to 50 µm with very good accuracy and excellent surface finish. Post-print processing involves removal of support material by rinsing.


Jet (PolyJet/ProJet) 3d Printing



3D jet printing is just what it sounds like, a more sophisticated big brother of the inkjet printer. Instead of ink being jetted or sprayed onto paper in a single layer, a resin or wax is jetted onto support material, and then onto previously sprayed layers until the part begins to take on depth and shape (Figure 1).

3D Jet printers may have a single print head like a computer printer, or they may have multiple heads to cover the width of the working platform. Either the print head moves across the working platform, or the platform moves back and forth under stationary print head(s). The 3D Systems and Objet printers use a UV lamp or a light source to harden the resin or wax after each layer is jetted. The Solidscape printer jets a heated wax that cold-cures in place and does not require exposure to a UV light source.

Typical layer thickness ranges from 16 µm to 50 µm with excellent accuracy and surface finish. Post-printing processing is simply removal of the support material, usually with a water or oil bath and simple rinsing. Most systems have self-cleaning print heads, so no user intervention is required. The curing light source, if necessary, is usually a Xenon lamp with a long service life.

An example is the The ProJet™ CPX 3000 3D Production System. It uses proprietary Multi-Jet Modeling (MJM) technology combined with new VisiJet® CPX200 wax build Material and new VisiJet® S200 dissolvable wax support Material to produce reportedly 100% RealWax™ patterns that are designed to perform like injected wax patterns in lost-wax casting processes.

 

3D printing Stereo Lithography Apparatus (SLA)



Stereo Lithography Apparatus (SLA) 3D printing uses a UV-sensitive liquid resin as the working material. A UV-laser is projected on and moves across the reservoir of the resin build material, illuminating and hardening the liquid resin only in the areas where the part is being printed. If multiple parts are being printed, each part is traced on the resin by the laser. The platform holding the part or parts lowers after each layer is printed, and a wiper blade spreads more build material uniformly across the working space. The UV laser makes another pass, tracing the outline of the next layer for each part in the print job. The process is repeated layer by layer until the job is complete. SLA technology allows for varying the layer thickness throughout the printing process. Some layers can be 100 µm thick where accuracy is not critical and then dialed to 50 µm or less when greater accuracy is required.

SLA printing technology is available with a wide variety of materials. A 25-µm to 50-µm layer thickness is achievable with excellent accuracy and good surface finish. SLA typically has slower build times due to the laser outline of each part. Post-print processing may require cutting the final part from the support material, removal of excess material, and the parts placed in a UV oven for final curing.

 

Selective Laser Sintering (SLS)



Selective laser sintering (SLS) is an additive manufacturing technique that uses a high power laser (for example, a carbon dioxide laser) to fuse small particles of plastic, metal (direct metal laser sintering), ceramic, or glass powders into a mass that has a desired 3-dimensional shape. The laser selectively fuses powdered material by scanning cross-sections generated from a 3-D digital description of the part (for example from a CAD file or scan data) on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed.

3d printing Selective Laser Sintering


Direct Laser Metal Sintering (DLMS)



DLMS uses a metal powder and SLS typically uses a plastic powder. The powder is spread across the working platform. A laser traces the outline of each part being printed, fusing (DLMS) or melting (SLS) the powder to the layer below it. The platform is lowered, a new layer of material is spread across the platform and the process repeated until the print job is complete.

DLMS technology has traditionally only been available for printing non-precious metals. Recently, Argen has developed its own materials and techniques for the EOS machine that allows them to provide both non-precious and noble metal copings. Post-print processing requires cutting off the support material.

 

Conclusion



Additive manufacturing technology in the dental industry is gaining popularity. See also 3d Products in Dental Industry. Materials and printing techniques continue to improve as manufacturers receive feedback on what is needed in terms of performance. Available materials are often manufacturer- and, sometimes, machine-specific. Be sure to check with the manufacturer on available materials for any printer under consideration for purchase. Most manufacturers are more than willing to send sample parts if they are sent an STL file to work with. It is a great way to assess the accuracy, finish, and workability of the material produced from the printer.

3D printing technology has been used for years for rapid prototyping (RP). Equipment manufacturers often want to create a prototype part without investing in expensive tooling. Typical use for RP technology has been same-part, small-volume production, with very good to excellent accuracy. The dental industry requires custom-part, single-unit production, with excellent accuracy. The volume of single-unit production in the dental industry is unlike anything the RP industry has encountered before. Dentistry is quite possibly the ultimate industry for RP technology to move into. Additive manufacturing equipment makers and material suppliers for these printers are already taking notice.

 

- Current applications -

 

Objet’s focus on digital dentistry



When looking for examples of current applications of 3D printing, you’ll find that Objet is a real market leader due to their high resolution printers, the Objet Connex and the Objet Eden series. Because these series can promise such high resolutions (down to 6 µm), it is the only real candidate for a precision industry such as digital dentistry.

What makes 3D printing interesting for dental lab owners is that the labs are are able to save time and labor, while at the same time improve the quality and precision of dental parts they manufacture. For a growing number of dental lab owners, digital dentistry is a fact. They have incorporated CAD/CAM automation into their strategic business models.

As Objet says: “At the heart of the new era in digital design is 3D printing. By combining oral scanning, CAD/CAM design and 3D printing, dental labs can accurately and rapidly produce crowns, bridges, stone models, and a range of orthodontic appliances for dental offices.”

 

Here are five showcases of companies that have incorporated 3D printing in their business models:

ClearCorrect (based in Houston Texas) manufactures clear aligners and serves over 11,000 orthodontic clients. The Objet 3D Printers can rapidly produce whole trays of individually-customized digital stone models which serve as extremely accurate base-mold tools upon which the clear aligners are then thermoformed.

Apex Dental Milling use the Objet Eden260V 3D printer to turn digital impressions into solid dental models for dental and orthodontic clients.

Albensi Dental Laboratories explains the benefits of an Objet 3D printer to their workflow, digitizing their dental process. The benefits include much more accurate dental restorations, higher precision 3D models, delivery times reduced from 5-7 days to 2-3 days, and happier customers.

AB Dental, a global provider of dental surgical guides, describes how their in-house Objet 3D printer allows them to digitally produce surgical guides for the mouth. The use of 3D printers enables AB Dental to rapidly produce highly accurate, customized surgical guides in see-through bio-compatible material and without the need for slow manual work.

Clearstep is a UK based orthodontics lab using Objet 3D printers to rapidly produce customized teeth models for the production of clear aligners and clear positioners. The move for digital orthodontic workflow with the use of Objet 3D printers has enabled the company to achieve consistent accuracy, consistency and speed for their customers. 

Artificial Jaw with 3d Printing

A 83-year-old woman chews, talks and swallows using an artificial jaw from a laser printer is rolled. She gets the credits for being the first human, talking with a 3d printing generated jaw. The technique was developed in Hasselt and Leuven. She suffered from a long lasting and rapidly progressive infection of almost the entire mandible with a large wound in her face. In order to retain an open airway, function of swallowing and chewing, surgical removal of the entire mandible was necessary to cure the patient.

The operation was performed in June 2011 in the Orbis Medical Centre in Sittard (Netherlands). The lower jaw of an elderly Dutch woman was completely replaced by an artificial jaw made of titanium. It was manufactured by a 3D printer exactly the right size and had been printed layer by layer.

By inflammation of the jaw , it was  so badly damaged that it all had to be removed. Usually what follows is  a heavy micro surgical repair that takes sixteen hours and can require several fragments of donor bone so that it can be reconstructed and to be put together.

But with the age of the patient in mind, the surgeons prefered a customized and one-piece implant, which was designed and produced in Hasselt, Leuven.

Fast operation

The operation in which the jaw was implanted, took less than four hours. “We prevented the lady a long and risky surgery saved,” says Jules Poukens of Hasselt University, who with colleague Ivo Lambrichts and Ingeborg Kroon Burgh were responsible for the design of the artificial jaw. “Shortly after she was awakened from anesthesia, and she spoke a few words, and the next day she could speak and swallow normally again.”

The mandible, including joint parts, was printed layer after layer by the Leuven company LayerWise.They used a 3d printer with titanium powder. During the printing process the powder melted, so that no glue or bonding agent was needed. The printer employed the art jaw also to contain cavities which muscles can attach to, slots through which blood vessels and nerves are guided and mandibular dental bridges and dimples so a denture can be screwed.

“The job was done in a few hours,” says engineer Peter Mercelis of LayerWise. With classical techniques to implant manufacturing (milling or casting in a mold), it takes something a few days.

The jaw was then coated with biokeramische bioceramics in Leiden, to be compatible with the tissue of the patient, and eventually weighed 107 grams Thirty grams heavier than a natural lower jaw, but not unpleasant for the patient, according to Mercelis.

“Beautiful, beautiful, ‘says Hubert Vermeersch, Department Head and Neck Surgery at UZ Gent. “A jaw should move in all directions. Tendons and muscles must be able to attach, and that seems perfectly succeeded.”

“Beautiful art also, with openings for nerves and blood vessels. Thus, the sensitivity in her lady lips can be restored. This is very important for a patient. Clever that they have put a coating over it, to prevent rejection. ”

3d printed implants

Implants for medical use are manufactured wiht 3d printers all over the world. Millions of people around the world have implants in their mouth with (variants of) this technique. And in Belgium, several people have already implanted and printed femurhead, cheekbones or skull. “But a complete lower jaw, no, that had never happened anywhere,” says Peter Mercelis of LayerWise

According to Hubert Vermeersch, the technique has a small risk that the implant in the course of time becomes exposed in the tissue. “But the risk is just as high as with classical techniques.”

The cost of the artificial jaw is “between 7,000 and 12,000 euros, according to engineer Maikel Beerens of Xilloc Medical in Maastricht. More expensive than classical implants and not reimbursed by health insurance. “But because the operation is much shorter than a classical one, you’re better off at once,” said Ingeborg Kroon Burgh of UHasselt.

The elderly woman is now fine. “In two weeks she gets artificial tooth roots in her jaw,” says Peter Mercelis. “Then we screw dentures. A loose dentures just does not work – that would irritate her gums too much. “