The Digital Revolution: Rapid Prototyping: the Next Generation of CAD/CAM
Posted Apr 28, 2011 in Digital Dentistry
LMT looks at the next generation of automated technology: rapid prototyping, or additive manufacturing. Developed in the 1980s, rapid prototyping technology has been used in the automotive and aerospace industries. Now that a greater degree of precision can be achieved, automated systems for the rapid production of precious metal substructures are being introduced to the dental laboratory market. Here, LMT takes a sneak peek at BEGO USA's new system.
Much of the excitement about CAD/CAM has been focused on milling all-ceramic and non-precious restorations, leaving fabrication of precious metal frameworks to conventional methods--until now. The next generation of CAD/CAM systems on the horizon employs rapid prototyping technology and makes automated production of precious metal substructures a reality.
These new systems* take a different approach to substructure fabrication: instead of milling down a block of material--what's called subtractive manufacturing--they create the substructure by adding powdered metal in layers and bonding them together. Unlike milling, this additive process does not result in material waste because the unused powders can simply be recycled, making it a cost-effective, efficient method of processing precious copings and bridges.
LMT got a sneak peek at one of these new systems when it visited BEGO USA's Lincoln, Rhode Island facility in November. The BEGO Medifacturing System fabricates single-unit copings and up to four-unit bridge frameworks in gold, non precious, and titanium alloys (other alloys are to be introduced soon). The system is in use at over 70 laboratories in Germany. BEGO received FDA approval in September and the system is currently beta-testing at two laboratories in the U.S.
Like CAD/CAM milling, rapid prototyping first requires you to scan a die to create a digital 3D representation on your computer screen (called a computer-aided design or CAD). BEGO's Rob Brunette demonstrated how to scan a three-unit bridge using its system, which is comprised of a scanner, computer and software to scan the model and design the substructure.
To ensure that the margins are accurate in the CAD, the BEGO system takes two separate scans. First, Brunette placed all three dies in the center of the scanning unit's cradle and four cameras took pictures at six different angles; the dies were then scanned individually. The 3D image appeared on screen and Brunette then used the software to capture the margins of each scanned die (you can use the software's automatic function, trace the margin manually or use a combination of both). Once the margins were adequately captured, he launched the Softshape CAD software to adjust the connectors and pontics and the design was complete.
Had he been working on a live case, Brunette would have sent the CAD data via the Internet to the manufacturing center at Bego's headquarters in Bremen, Germany. There, a manufacturing unit slices the digital image into thin, horizontal layers; each slice represents a layer of metal powder that will be fused together to create the final substructure.
This type of technology uses different ways to fuse the layers of powder together, including Selective Laser Melting (SLM) which is used by the BEGO system. In SLM, a thin, even layer of metal powder is applied to a base plate. A laser scans the surface of the powder and fuses the areas of the powder according to the data. The baseplate is lowered slightly--about 20 microns--and a new powder layer is applied; the process is repeated until the substructure is complete. The substructure usually arrives at the laboratory 72 hours after the data is sent.
A user's perspective One of BEGO's beta-test sites is Precision Craft Laboratory in North Providence, Rhode Island, which has been using the system for about five months. Since General Manager Ryan Napolitano had already implemented two CAD/CAM milling systems that required him to learn how to scan and design the substructure, implementing a third CAD/CAM system was relatively easy. "Ninety percent of getting the systems to work properly is learning the software and many CAD/CAM systems are very similar," says Napolitano. "The first time around we had a trainer here for about four days because we had to learn not only the software, but how CAD/CAM worked in general. This time we had the learning curve mastered and were able to pick up the BEGO system in about half a day."
Now that the system is fully integrated, its ability to fabricate precious metal substructures is proving to be a boon to the lab's production. About 70% of the lab's work is precious metal and the system helps meet the demand for these restorations. It eliminates waxing, casting, investing and divesting; instead, technicians design the unit and then receive the finished product. The lab is doing the same amount of restorations it did before, but fewer technicians are doing the work and the metal technicians are freed up to do other laboratory work or be cross trained in other areas.
Napolitano is also pleased with the quality of the substructures. "The margins are great, the fits have been accurate and I can even modify the fit of the coping if I want to. When we get the coping or framework back, we spend about two to three minutes thinning out the margins, sandblasting and then they're ready for porcelain."
BEGO formally launches the system in 2006 and plans to open a U.S.-based manufacturing center by the end of the year.
*None of the systems that produce precious metal substructures are on the market yet; in addition to the BEGO machine, there is one other system in development.
BEGO at a glance
Bremer Goldschlagerei--today known as BEGO--was founded in Germany over 115 years ago by Dr. H.C. Wilhelm Herbst as a manufacturer of gold foils for use in fillings and inlays. Today, the company's main products are alloys, casting machines, investments, partial denture systems and equipment and, most recently, the BEGO Medifacturing CAD/CAM system.
BEGO has approximately 250 employees in five locations worldwide, sells to 105 countries and is run by Joachim Weiss, who has been with the company for 60 years. Weiss, who just celebrated his 80th birthday, still comes to the office three to four days per week, but has handed over the daily operations to his son, Christoph Weiss, who is also the president of BEGO USA.
BEGO USA was founded in Rhode Island in 1991 and today employs nine, including three people in the warehouse and a part-time laboratory instructor for the in-house training laboratory.
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