No two people’s teeth are identical and the type and extent of tooth damage is unique to each individual, making bespoke manufacture of crowns, bridgework and implants a prerequisite. Traditional methods of making such dental restorations traditionally use lost wax casting technology that has barely changed in 100 years. Now, additive manufacturing (AM), or 3D printing, is replacing the labour-intensive lost wax process, resulting in many benefits.
Bill Oremus, President of Rhode-Island based dental prosthetics manufacturer, BEGO USA, predicts, "Our current product line based on lost wax is probably going to be obsolete in ten to fifteen years. The end of casting is approaching as the introduction of layer-by-layer manufacturing to dentistry begins to alter the landscape.”
With an eye to the future, in 2011 BEGO USA launched an on-site production service for non-precious alloy restorations using a direct metal laser sintering (DMLS) system from leading manufacturer, EOS GmbH, whose UK subsidiary is in Warwick.
Less than a year after installing its EOSINT M 270 AM system, BEGO USA was producing hundreds of units a week from CAD data, each prosthetic being fully dense and without porosity.
“Our customers simply send us an STL file of a patient’s mouth scan and, after file review, we manufacture the coping in about 48 hours,” explains Oremus.
The laser sintering machine, which holds a vertically moving bed of powdered metal, builds crowns and/or bridges simultaneously, layer by layer, each one successively solidified by a focused laser beam. The DMLS system runs automatically, quickly and economically, providing a typical accuracy of ± 20 microns. Whereas a traditional casting process can produce about 20 dental frames per day, DMLS manufacturing is capable of up to 450 units of crowns and bridges in the same time period.
Oremus continues, “The restoration only needs some rubber wheel finishing in the margins and it’s ready for veneering with ceramics. In the case of a bridge, the end product doesn’t need sectioning and just drops into place.
“EOS technology is giving us a lead over the competition at the moment because we are able to do larger bridges with more than three or four copings in a row.
"The quality of the restorations is truly excellent, the surface structure of the copings is much better, and the marginal integrity is phenomenal. Moreover, we save cost and time.
“Whatever alloy we are working with, we find that EOS machines are head-and-shoulders above others in terms of control over laser beam size and of different restoration geometries.”
He compares ten different restoration cases of long-span bridges, side-by-side, to underline this point. “If you were to put them through the old lost-wax technique you’re probably looking at only 50 to 60 per cent accuracy.
That means a lot of remedial work, not to mention increased waiting time for the patient. Using our EOS system today, we are getting a 90 to 95 per cent success rate in a lot less time.”
Since its EOS system can work with virtually any properly prepared metal powder, BEGO USA has patented its own high-performance chrome-cobalt-molybdenum alloy, Wirobond C+. According to Oremus, the material contains more than 20 per cent chromium, which, during manufacturing, creates a passivity layer that prevents the release of free ions and ensures high biocompatibility.
Next on the materials menu for BEGO is a noble powder, a chrome-palladium-trace element alloy, that the company is in the process of developing for DMLS-manufactured restorations. Palladium, a platinum-group metal, provides strength, stiffness and durability. The additional trace elements contribute an improved coefficient of thermal expansion and better elongation and malleability.
The fact that laser sintering systems can be run with a wide variety of validated materials is of particular interest to the dental industry, which is always on the lookout for alloys with improved characteristics. Durability and performance are key in restorations, as the muscles of the jaw generate huge force on teeth and prostheses also have to withstand thermal expansion and contraction.
Whatever the materials used, DMLS uses less of them than traditional manufacturing methods.
"A major advantage is the cost-effectiveness of the build-up technique using DMLS versus other CAD/CAM processes that are subtractive processes via milling or pressing,” says BEGO USA’s CAD production manager Ryan LeBrun.
“When you get into high-end metals, you’re looking at portions of your profit just ground away, but there is almost no waste with additive manufacturing.
"We filter any unused powder and reuse it on the next production run. We are able to pass our savings on to the laboratory and the technician to help optimise their profit.
"What's more," concludes Oremus, "advances in the digitalisation of dentistry are primed to support acceptance of the technology.
“The use of chair-side mouth scanners will make CAD modelling increasingly common and further drive the use of additive manufacturing in dentistry.”
Bill Oremus, President of Rhode-Island based dental prosthetics manufacturer, BEGO USA, predicts, "Our current product line based on lost wax is probably going to be obsolete in ten to fifteen years. The end of casting is approaching as the introduction of layer-by-layer manufacturing to dentistry begins to alter the landscape.”
With an eye to the future, in 2011 BEGO USA launched an on-site production service for non-precious alloy restorations using a direct metal laser sintering (DMLS) system from leading manufacturer, EOS GmbH, whose UK subsidiary is in Warwick.
Less than a year after installing its EOSINT M 270 AM system, BEGO USA was producing hundreds of units a week from CAD data, each prosthetic being fully dense and without porosity.
“Our customers simply send us an STL file of a patient’s mouth scan and, after file review, we manufacture the coping in about 48 hours,” explains Oremus.
The laser sintering machine, which holds a vertically moving bed of powdered metal, builds crowns and/or bridges simultaneously, layer by layer, each one successively solidified by a focused laser beam. The DMLS system runs automatically, quickly and economically, providing a typical accuracy of ± 20 microns. Whereas a traditional casting process can produce about 20 dental frames per day, DMLS manufacturing is capable of up to 450 units of crowns and bridges in the same time period.
Oremus continues, “The restoration only needs some rubber wheel finishing in the margins and it’s ready for veneering with ceramics. In the case of a bridge, the end product doesn’t need sectioning and just drops into place.
“EOS technology is giving us a lead over the competition at the moment because we are able to do larger bridges with more than three or four copings in a row.
"The quality of the restorations is truly excellent, the surface structure of the copings is much better, and the marginal integrity is phenomenal. Moreover, we save cost and time.
“Whatever alloy we are working with, we find that EOS machines are head-and-shoulders above others in terms of control over laser beam size and of different restoration geometries.”
He compares ten different restoration cases of long-span bridges, side-by-side, to underline this point. “If you were to put them through the old lost-wax technique you’re probably looking at only 50 to 60 per cent accuracy.
That means a lot of remedial work, not to mention increased waiting time for the patient. Using our EOS system today, we are getting a 90 to 95 per cent success rate in a lot less time.”
Since its EOS system can work with virtually any properly prepared metal powder, BEGO USA has patented its own high-performance chrome-cobalt-molybdenum alloy, Wirobond C+. According to Oremus, the material contains more than 20 per cent chromium, which, during manufacturing, creates a passivity layer that prevents the release of free ions and ensures high biocompatibility.
Next on the materials menu for BEGO is a noble powder, a chrome-palladium-trace element alloy, that the company is in the process of developing for DMLS-manufactured restorations. Palladium, a platinum-group metal, provides strength, stiffness and durability. The additional trace elements contribute an improved coefficient of thermal expansion and better elongation and malleability.
The fact that laser sintering systems can be run with a wide variety of validated materials is of particular interest to the dental industry, which is always on the lookout for alloys with improved characteristics. Durability and performance are key in restorations, as the muscles of the jaw generate huge force on teeth and prostheses also have to withstand thermal expansion and contraction.
Whatever the materials used, DMLS uses less of them than traditional manufacturing methods.
"A major advantage is the cost-effectiveness of the build-up technique using DMLS versus other CAD/CAM processes that are subtractive processes via milling or pressing,” says BEGO USA’s CAD production manager Ryan LeBrun.
“When you get into high-end metals, you’re looking at portions of your profit just ground away, but there is almost no waste with additive manufacturing.
"We filter any unused powder and reuse it on the next production run. We are able to pass our savings on to the laboratory and the technician to help optimise their profit.
"What's more," concludes Oremus, "advances in the digitalisation of dentistry are primed to support acceptance of the technology.
“The use of chair-side mouth scanners will make CAD modelling increasingly common and further drive the use of additive manufacturing in dentistry.”
