3D Printing: No Longer Just an Experiment
Additive technology has become an integral part of the workflow for one dental laboratory
By Don Albensi Jr. and Chris Halke
Over the past several years, the authors’ laboratory has used additive manufacturing to augment and improve its traditional workflows. The laboratory’s first endeavor into additive manufacturing came in 2003 as part of a collaborative project with ExOne’s Imagen Printed Copings. The goal of the effort was to develop a printable gold coping to serve as a substructure for PFM crowns, which were the dominant restoration type at that time. If successful, this process would eliminate older, more labor-intensive methods of casting. Cases were scanned into the computer and digitally designed, and then a metal substructure was created using gold powder and a binder. Ultimately, although the technology proved successful, the logistics and cost of securing the gold powder needed for the process were not well matched to a large production environment.
Five years later, the authors’ laboratory used that scanning and design technology to print wax copings in a wax printer. While traditional wax casting was still utilized, the scanning process saved several steps of labor at the beginning of case processing, such as painting cement spacers, which was now controlled digitally.
Around that time, a new monolithic material called lithium disilicate was gaining market traction. In addition to being stronger than PFM, the super-heated lithium disilicate ceramic could be pressed into the same type of molds that the metal PFM substructures had been cast into for years. By taking the pressing process and adapting it to a CAD software system for crown design and printed wax patterns, the laboratory was able to reduce the turnaround time on a lithium disilicate crown to 4 days in the laboratory—an unprecedented timeframe in the industry (except for in-office milling). Additionally, these printed and pressed crowns were shown to have superior marginal fit and anatomical clarity over milled restorations of the day.
Realizing the benefits of both the accuracy and turnaround time of additive manufacturing, the authors’ laboratory started to explore additional ways of integrating this technology. The next step was to develop a way to in-source the printing of models from intraoral scans. Although this process is common now, no such developed laboratory solutions existed when the project began in 2010. Seeing an opportunity to further decrease the turnaround time on crowns, the laboratory developed a rudimentary method of using the supplied digital impression from an intraoral scanner to fabricate its own model and complete the case in just 3 working days. In addition to the decreased in-laboratory time, the cost was a fraction of what it had been. After proving the concept, the laboratory joined three manufacturers to develop and qualify a process for on-site printing industry-wide. Using a 3D printer and a beta release of a model-building software, the laboratory developed and printed several test scans and models, and then sent them to a manufacturer’s testing facility for analysis of accuracy.
Through iterations of research and development, the laboratory optimized workflows and capacities with the use of the 3D printer. Thanks to improving technology, the laboratory learned that existing digital workflows and using a new printer on the market enabled an increase in production while reducing processing time. The authors discovered a less expensive material that made post-processing of models less time-consuming, reducing the post-processing labor by approximately 80%.
The 3D printer is becoming an integral part of the authors’ production workflow. The ROI on each of the laboratory’s new 3D printers is now less than a year. Printing models for all intraoral scans has become common practice. The laboratory also has begun scanning qualified traditional triple tray impressions with model scanners and printing small models to decrease turnaround times on monolithic restorations.
As technology and solutions improve, processes and materials also evolve. A recent addition to the additive manufacturing mix is partnering with an outsourcing center to assist with a process known as selected laser melting (SLM). This has improved workflows pertaining to metals for better fit, consistent results, increased productivity, and pricing. SLM has enabled the authors’ laboratory to reduce labor costs due to the reduction within investing, casting, etc, using SLM for high-noble, noble-25, noble-85, and non-precious restorations.
The investment in additive manufacturing provides a stable venue for growth and scalability. Research suggests that new advancements within additive manufacturing will emerge that will enable laboratories to continue investing, finding new ways to evolve, and growing within an industry that is thirsty for new technology and material choices.
Don Albensi Jr. is COO of Albensi Dental Laboratories in Irwin, PA, and Chris Halke is the company’s CAD/CAM Supervisor.
3D Printing Now and in the Future
By Daniel Alter, MSc, MDT, CDT
We live in exciting times as the evolution of dental technology moves forward, particularly in the 3D printing arena. This technology is progressing rapidly, as are the possibilities of new printable materials and restorative options. 3D printing is an additive manufacturing process, whereby materials are added according to geometric-specific sequences generated in the CAM software, guided by a CAD output. However, unlike other manufacturing technologies, 3D printing enjoys a multitude of differing output technologies, capabilities, possible output materials, treatment solutions, and varying levels of precision. At the onset of 3D printing, the technology was geared mainly to developing physical models and dies from digital scans and/or 3D renderings. These technologies have evolved to incorporate a higher level of precision necessitated with the manufacturing of fixed restoration and implant cases. Looking forward, many companies—small, mid-size, large, and startup—are constantly innovating and pushing the limits of what can be 3D printed, for varying purposes.
In a recent 3D Printing Industry article, “Dentistry is getting the 3D Printing Treatment,” Lydia Mahon details how 3D printing is advancing quickly and making huge strides in the additive manufacturing industry. Because 3D printing now offers lower prices, better quality products, significantly decreased production time, and better outcomes, estimates indicate that “the growth of 3D printed services and products [in 2015] was 26%, which is a net worth of around $5.2 billion.”1 It is no wonder that this new technology’s unprecedented ability to make replacement teeth is getting so much attention, potentially inspiring a revolution in the industry.
Current 3D Printing Technologies
In dentistry, five additive technologies are commonly utilized, falling into two main categories. The first category prints waxes and plastics (polymers) to create complex geometric objects such as full-contour wax-ups or substructures, surgical guides, and models and dies. This category deploys technologies such as Digital Light Processing (DLP), jet, and stereolithography apparatus (SLA). The second category of printing technology manufactures metallic objects and is often used for producing copings, full cast crowns, chrome cobalt partial dentures, and implant components utilizing either selective laser sintering or melting technologies (SLS or SLM, respectively). The way each technology prints is different, not only in materials and outputs, but also in build plates and heat or laser/light. Additive manufacturing starts with an empty platform, tray, or build plate, and successively builds a complex 3D object. Suitable CAM software slices the 3D electronic design file—classified with a nomenclature of Standard Tessellation Language (STL), which is an open-formatted CAD file of a complex geometry—into layers of fixed thicknesses. The printer then processes each layer, usually from the bottom up, but some 3D printers immerse and cure as the build plate moves up and out of the liquid, creating an extremely accurate final product.
Benefits of 3D Printing
Digital manufacturing utilizing 3D printing or additive technologies has boasted superior geometric results for fits, curvatures, and particularly complex geometric digital designs. The technology is able to build from the ground up in a succession of precision layers, incorporating every angle and curve—a task very difficult to achieve even with the most sophisticated 5-axis milling machine or CNC apparatus. Furthermore, it has also alleviated the less-than-optimal need to over-mill in an attempt to attain the proper angulation, which is often necessary in order to mill at the correct angle or inclination severity. Over-milling can potentially compromise the strength of digitally manufactured products and create weak spots or areas, which could create negative results once inserted in the mouth or even during post-processing. With 3D printing technology, severe angles do not pose any critical issues, because precise, segmented layers are built over the digital surface angulation, which create a very intimate fit between the restoration or product and the accepting structure.
Some of the newer printable materials expected to add great value are awaiting their FDA approval. Additive technology materials, in the dental landscape, go through a regimented process involving rigorous testing in order to gain FDA clearance and verify that they’re suitable for the oral environment as a long-term restorative solution. Manufacturers are making great strides in this respect and are heavily vested in resources and efforts to make the potential a reality.
The Future of 3D Printing in Restorative Dentistry
The restorative dentistry industry is constantly striving to achieve the most efficient, economic, and best-in-class materials to manufacture strong, vital, and esthetic restorations or medical devices for our clients and their patients. Undoubtedly, when we can produce a restoration with the above indications using 3D printed technology, we will get the best of both worlds: superior fit, efficient or lean manufacturing, and esthetically pleasing outcomes. Some extremely interesting and exciting advances have been made in 3D printing with regard to printing ceramic and zirconia nano-sized particles. At a recent Formnext 3D Additive Manufacturing Show in Frankfurt, Germany, XJet (xjet3d.com) released its ceramic nanoparticle jetting. “With the use of XJet’s nanoparticle jetting, 3D printed teeth could now be a possibility,” a 3Dprintingindustry.com article says. “All of a sudden you can start thinking about ceramic coping or ceramic crowns and that has huge potential to reinvent the way the dental world works.”2
The possibilities and innovations in 3D printing in the restorative dentistry environment are endless, as noted in a recent article in The Guardian: “Dutch researchers at the University of Groningen are working on the creation of a 3D-printed tooth made of an antimicrobial plastic that kills the bacteria responsible for tooth decay on contact.”3 Whether through bioprinting or ceramic/zirconia nanoparticle printing to achieve esthetic restorative outcomes, the future is very bright for the dental technologist. Staying abreast of these new developments and innovations will certainly maintain the dental laboratory’s position at the forefront of innovation and provide the ability to remain competitive and efficient in the process.
Elevate and inspire with knowledge
References
1. Mahon L. Dentistry is getting the 3D Printing Treatment [3D Printing Industry website]. June 24, 2016. Available at: https://3dprintingindustry.com/news/dentistry-getting-3d-printing-treatment-83533. Accessed 1/24/17.
2. Clarke C. XJet aiming to revolutionize dental industry [3D Printing Industry website]. November 21, 2016. Available at: https://3dprintingindustry.com/news/xjet-aiming-revolutionize-dental-industry-99130. Accessed 1/24/17.
3. Basulto D. The latest advance in 3D printing: replacement teeth [The Guardian website]. October 31, 2015. Available at: https://www.theguardian.com/technology/2015/oct/31/3d-printing-plastic-replacement-teeth. Accessed 1/24/17.
