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Marta Kazmierowska graduated from Hunter College, the City University of New York, with a Bachelor’s degree in chemistry. After returning to Poland she pursued a Master’s degree in green chemistry at Gdansk University of Technology. During her second degree studies, she gained extensive practical knowledge about various 3DP technologies. She practiced at LITHOZ in Vienna where she worked with the lithography-based ceramic manufacturing (LCM), and in Pomeranian Science and Technology Park in Gdynia with selective laser sintering (SLS) and PolyJet technology. Right now she is a CAD/CAM supervisor and EOS M100 operator at a dental prosthesis laboratory. She is interested in all 3D printing technologies and their application in medical and non-medical fields. In her free time, she is building anatomical models from CT data.

Before I discovered 3D printing (3DP), I had several work experiences. In college, I worked as an assistant in a chemistry laboratory and in a pharmacy. I had also previously been a babysitter, a secretary and later on a teacher in an international school. Each of these jobs provided me with different and rich experiences that shaped my personality and way of thinking. However, for me, none of these experiences were truly fulfilling, truly absorbing, or my own… I felt that I was doing things that were already established by somebody else, sort of a template that I’d fill in. And I had an everlasting feeling that I need to do something innovative. I decided to quit the teaching position I had and enrolled on a master course at the Gdansk University of Technology. I quickly found a mentor and during one of our conversations she mentioned 3DP. I started researching the topic – I was mesmerized. That was it! There was one more thing that I knew right away, there is no time to waste! I need practice, practical knowledge, hands-on experience, not only dry facts from books. Through my professor, I contacted amazing people at LITHOZ in Vienna and left for a three-month practice. That experience was one in a lifetime, I gained knowledge, experience and I made true friends. When I came back to Poland, I saw that the 3DP Lab in the Pomeranian Science and Technology Park in Gdynia was opened, so I went there and asked if I could do some volunteering. I was lucky, again. The people were kind and open to share and exchange their knowledge.
The freedom, almost limitless possibilities of different 3DP techniques and the people from the field inspire and motivate me every day. I want to use and spread the power of 3DP to people’s advantage because many things can be done better, faster and generate less waste.
Therefore, I’m happy to be a CAD/CAM supervisor and EOS M100 operator working with CoCr at the dental prosthesis laboratory in Gdansk. I embarked on a mission to convince people from the dental and dental prosthesis field about advantages of the innovative CAD/CAM technologies with the focus on 3D printing.
Creation of precise, fully-functional and biocompatible metal crowns and bridges using conventional lost-wax casting methods is a laborious, multi-step, and time-consuming process, which may not always produce high-quality dental prosthesis parts. The errors can occur at early stages, during impression collection at the dentist, and build up during wax modeling, during metal casting, and during post-processing. The casting process by itself is difficult to control. As a result, the obtained part can have many irregularities, gaps, and air bubbles, which complicate and extend the post-processing step. Also, thick casting sprues, which are directly melted with the crowns, have to be cut away and the surface of a crown have to be polished.

Fig.1. 6-point bridge and one crown obtained with the conventional lost-wax casting technique. Irregular surface, air bubbles, thick and heavy sprues require laborious and time-consuming post-processing, which also generates a lot of waste.

A metal crown that is too tight, too loose or doesn’t fit on a model, is a nightmare that can happen to the most skilled and experienced dental prosthesis technician. Additionally, when producing big and multi-pontics bridges, there is a high chance that they will bend. Another disadvantage of the conventional metal casting is waste production.
Innovative CAD/CAM technologies allow to: collect precise digital impressions, and then design and produce very detailed metal crowns and bridges. The intraoral scanners are more comfortable for the patient since no goopy, short-lived impressions are needed. The entire scanning procedure happens in real-time at the dentist’s office. A doctor, in a split of a second, electronically sends obtained scans to a dental prosthesis CAD/CAM department, where specialized technicians make projects of metal crowns and bridges on the computers. The scans and projects can be stored and accessed at any time, eg. for retrospective studies, whereas most of the impressions can be only used once. The digital impressions can also be 3D printed in eg. digital light processing (DLP) technology. The 3DP models are more detailed than the gypsum models and almost no waste is generated during their production. If the dentist’s office doesn’t have an intraoral scanner, conventional impressions can be sent to our laboratory. In this case, we make our .stl projects by scanning gypsum models.
Obtained .stl project is then analyzed in additional programs, which check for errors in a digital net, orient the part and generate the support structures. Once the part and its support structures are ready, they are transferred to the EOS M100 printer which uses the direct metal laser sintering (DMLS) 3DP technology.

Fig.2. EOS M100 printer which uses the direct metal laser sintering (DMLS) 3DP technology.
M100 produces precise, high-quality, high-density metal crowns and bridges in a matter of few hours with no human interference. The parts are built in a layer-by-layer fashion, by application of a thin metal powder layer by the ceramic coater and exposition of layers by a high-intensity ytterbium laser.

Fig.3. Ytterbium laser tracing and melting the contours of support structures on a thin surface of the evenly distributed powder.
Fig.4. Metal crowns and bridges produced on an EOS M100 printer in the DMLS technology. The detail of the parts is precise due to scanners which replicate exact morphologies of patient’s teeth and due to 30µm printing layer thickness. The surface of parts is smooth and easy to finish. More than 80 metal points can be produced in a single cycle!
After the finished run, the printer is carefully cleaned. The biocompatible, medical-grade CoCr powder is screened on a sieve of a specific size and reused in next cycles. Therefore, almost no waste is produced because only the material that is needed for the part and its supports are used. The parts on a building platform are then sanded and placed in the oven. The thermal treatment in the inert Ar atmosphere gives parts final structural properties and reduces the tensions so the probability of twisting and bending is minimal. After the thermal cycle, the parts are detached from the building platform and undergo post-processing. The support structures have a form of small pins they do not go deep inside the part. Therefore, they can be easily removed with pliers by a squeezing and twisting motion. Once the supports are removed, the parts need surface polishing and quick sanding, since the surface of printed crowns and bridges is already smooth and regular.

Fig.5. A Precise, detailed and smooth surface of DMLS metal dental prosthesis parts together with tiny, easy to remove support structures.
Due to the exact and detailed image obtained with a scanner and thin printing layer (30 µm) the fitting of even the biggest 14-point bridge is almost perfect, so no laborious fitting on the model is needed. Such parts are ready to be used for eg. porcelain application. Due to the precise DMLS technology, the density of produced metal crowns and bridges reaches almost 100% so there is no gassing during the porcelain application process.

Fig.6. Building platform with CoCr crowns and bridges.
Thanks to the innovative CAD/CAM technologies we are able to produce in one cycle more than 80 metal points in a matter of few hours! And we are able to do more than four cycles a day! Therefore, this technique minimizes the errors, amount of work and waste, producing a large number of high-quality parts in less than a workday!
I speak with dentists and dental prosthesis technicians on a daily basis and try to convince them to these innovative approaches. I believe that big and small obstacles can be overcome because of a wide variety of options and solutions that are recently available on the market. Every day these solutions expand and right now are at a hand’s reach and they don’t have to be costly. Therefore, I’m motivated to speak to doctors and technicians and make small steps towards creating better future for them and their patients.

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As companies continue to innovate, they are turning to 3D printing technology to build customized, patient-matched 3D printed dental and medical devices that incorporate biocompatible materials. Advances in 3D printing technology have made it possible to print human tissue using a combination of stem cells and biocompatible materials. Researchers are working on using 3D printing technology to print organs suitable for transplantation, with the goal of alleviating the shortage of donor organs and saving lives. Earlier this year, Vertex Dental, based in the Netherlands, developed the first CE Class IIa-certified materials, which are biocompatible, and approved for 3D printing dental applications such as dental splints, crowns, and bridges.
Biocompatible materials are not without risks. On June 16, 2016, the FDA issued a FDA Guidance entitled “Use of International Standard ISO 10993-1, ‘Biological evaluation of medical devices – Part 1: Evaluation and testing within a risk management process’” to assist manufacturers of devices that come into contact with the human body in evaluating the potential for an adverse biological response resulting from contact of component materials of the device with the body.
For suppliers of these component materials that are shipped to manufacturers to be integrated into end products used by patients, this raises the question of whether a component part supplier may be liable for injuries caused by defects in the end products. In other words, if a 3D printed device that comes into contact with a patient’s body causes an adverse reaction, can the supplier of the biocompatible material be held liable for defects in the finished product that incorporates the material?
In a decision published in May 2016, Webb v. Electric Co., 63 Cal. 4th 167 (2016), the California Supreme Court explained that suppliers of component parts are not liable for injuries caused by a finished product unless (1) the component itself was defective and caused injury or (2) the supplier participated in integrating the component into a product and the integration caused the product to become defect and cause injury. The reasoning is that while component suppliers must adequately warn buyers (e.g., manufacturers integrating the components into end products) of risks associated with the component, it is not reasonable to expect them to monitor all of the potential products that may incorporate their component part and all the potential risks associated with these finished products.

Furthermore, under the bulk supplier doctrine, where a raw material that is a component of a finished product, is supplied in bulk and intended for further processing (e.g., heating, cooling, etc.), the raw materials supplier is not liable for harm caused by the defective design of a finished product. The rationale is that it would be overly burdensome to require raw materials suppliers to become experts on all of the end products in which the raw materials may be used and investigate the use of these materials by manufacturers over whom these suppliers do not exert control.
To mitigates risks of liability, materials suppliers should provide adequate warnings of the inherent risks associated with these component materials to the immediate purchaser of these products and take reasonable measures to ensure that appropriate warnings will be conveyed to those encountering these materials. Suppliers should also disclaim warranties about the suitability of the materials for use in end products. Additionally, suppliers should notify manufacturers that they are responsible for determining the suitability of the component materials for the devices they are manufacturing.

About the Author :

Farah Tabibkhoei is a member of the Complex Litigation Group at Reed Smith LLP.  Her practice focuses on medical device product liability, managed care disputes, and 3D printing.  Farah can be reached at FTabibkhoei@ReedSmith.com.

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3D Printing in Dentistry: From a Broken Tooth to Digital Revolution
Nancy calls me at 1:30, “I just ate an olive pit and cracked my tooth. A big chunk of it is gone, it hurts and is really sharp against my tongue”. Nancy arrives at my office at 2 with half of her back molar has chipped off. Her teeth get scanned with an intraoral scanner and we design a digital crown. Next the design gets sent to a milling machine that precisely carves it out of a block of porcelain. At around 3:30 Nancy has a functional, permanent, esthetic new tooth in place of her chip and is back at work.
Nancy’s injury happens all the time in my office. Our digital workflow, computer assisted design and computer assisted milling (CAD/CAM) allows us to create strong and precise teeth restorations in under 2 hours. A few years ago this took two weeks.

Milling is a great way to make teeth but there are some limitations. The shapes we can mill are limited by the shape and size of the cutting instruments. In other words smooth round objects are easier to mill where as sharp or thin objects are difficulty. Teeth tend not to be smooth and round.
Color is another limitation of milling. It is very difficult to add different colors or translucencies to a milled crown. Currently the approximate color of a tooth is taken and a solid block of that color is milled into a crown. Teeth are not a single color but are actually made of multiple shades and opacities of enamel.

3D printing offers a solution to these limitations. By adding material we can make it almost any shape we want from a paper-thin veneer to a deep molar grove. It also has the potential to add different shades and translucencies to our restorations making them look more natural.
Currently we are using 3D printers in dentistry for surgical guides, temporary prosthetics and treatment panning. The big jump will be when we can throw away our milling machines and start printing veneers and crowns that can be placed permanently the same day of treatment.

Form 2, 3D printed night guard

Sirona the leading manufacture of digital crowns and milling machines suggests digital printers to still be several years away before they are ready for the dentists office.
One of the major limiting factors is that milling is really fast. It takes about 5 min to mill a block of porcelain into a crown then 15 min to bake it. 3D printing has a ways to go before it can catch up to those times.
As printing times get closer to milling I predict a fast adaptation of this technology. Printing opens up the possibility to produce a crown that can be color matched to adjacent teeth pixel by pixel. That will be a game changer is cosmetic dentistry.
About the Author: 


Dr. Russell Taylor received his Doctorate of Dental Medicine from McGill University in Montreal Canada. Subsequently, he went on to complete a residency in Advanced General Dentistry at the University of the Pacific in San Francisco. Currently, Dr. Taylor practice’s clinical dentistry in San Francisco and is an adjunct faculty member at the University of the Pacific Dugoni school of Dentistry. He also serves as a director for the San Francisco Dental Society. Dr. Taylor lectures throughout the United States on cosmetic dentistry as well as dental implants. He also volunteers within California in large-scale clinics that provide no cost dental service to the under served. Internationally, Dr. Taylor provides charity dental services in countries like Ecuador, Vietnam and the Fijian islands. He is focused on starting a residency program in Vietnam for new graduated dentists to help them better serve their community. Dr. Taylor’s is passionate about incorporating technology into in his dental practice to promote, maintain and restore oral health.

Interview: Dr. Nima Massoomi, Board Certified Oral and Maxillofacial Surgeon

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