CU Anschutz dental researchers shape the future of 3D printing

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What is the current state of 3D printing in dentistry?

Jeffrey Stansbury, Ph.D.: 3D printing is booming in the dental profession. Although this is only a minority of what is happening, it is growing rapidly and is expected to eclipse the reduction milling approach to manufacturing digitally derived dental appliances in the not too distant future.

Currently, materials are most important, which means that most of what is printed are dental models – replicas of the patient’s teeth for example. So while there is a great need to achieve higher performance 3D printable polymers that are suitable for long-term clinical function, here we are trying to go beyond standard 3D printing techniques and enable the production of devices. Fully functional strong and durable dental products produced via multi-material inkjet printing.

Kyle Sorensen, DDS ’25: In dentistry (with current 3D printing), we can do treatment planning, and you can also get a recording of the oral cavity. However, these casts or study molds are not used for direct dental application – it is just a snapshot of the patient’s mouth.

You can use these casts and molds for various applications, such as designing surgical guides or creating guards that prevent teeth grinding. But what our project offers is the possibility of creating intra-oral devices, such as dentures, bridges or implants, which can be used daily by patients.

What are the benefits of 3D printing for dental applications?

Stansbury: It has so many advantages in terms of delivery cost, delivery speed, material utilization efficiency, all kinds of things.

It’s the ability to 3D print a patient-specific design at very high resolution, which is a perfect fit for what 3D printing does. Mass customization is actually the terminology for what 3D printing can accomplish. These would be permanent dentures – or removable or partial – as well as crowns and bridges. It is these materials and the possibility of printing these materials in 3D in very high resolution.

What is 3D inkjet printing?

Stanbury: It’s like an inkjet color paper printer, where you can get any mix of colors on the fly. What we are looking for is to be able to precisely project droplets of multi-materials to obtain final unified polymers with localized control of material properties and aesthetic appearance to reproduce the differences between gums and teeth for example .

This is different from the conventional 3D printing used in dentistry today – vat-based printing – where you essentially create an object layer by layer as it is removed from the vat. We are producing new materials that far exceed what is possible with current vat-based printing and are advancing disposable materials even more radically.

Can you explain the science behind these new materials and how they are different from existing 3D printing materials?

Sorensen: Existing polymeric materials widely used in dentistry generally combine a chemically bonded network structure with secondary interactions that add strength and toughness. A good example is urethane dimethacrylate (UDMA) where the methacrylate groups react to produce the basic polymer network and the self-association of the urethane groups contributes to the overall performance. However, UDMA does not work for 3D inkjet printing because the association between urethane groups which is positive in the polymer state increases the viscosity of the ink in the pre-cure state where the jet of small, well-controlled droplets must take place.

A simple denture tooth button that was printed as a proof-of-principle demonstration of new materials being developed at the School of Dentistry.

Our new patented CU materials are monourethane dimethacrylates (MUDMA) which offer much lower viscosities than UDMA before polymerization while exhibiting equivalent mechanical properties in the final polymers. We then coupled our MUDMAs with a second monomer that interacts preferentially with urethane groups to bring the viscosity of the ink back into the jetting range while enhancing the reinforcing effects in the final polymers to achieve mechanical properties that appear well suited. clinical challenges in dentistry. .

The other interesting result is that our new material is more temperature resistant than what’s currently available on the inkjet platform, so it won’t warp when exposed to food. or hot liquids. So, in addition to being able to withstand more normal dietary activities, they are very strong and flexible materials that can be built with precision using multi-material inkjet printing.

How will determining the size and fit of these types of devices work in the future?

Stansbury: For the necessary digital design of a desired device, you can take two approaches. The first is that you can do an intraoral scan with an imaging tool. Again, it’s not a wand, but you carefully move it through the patient’s mouth and it captures a three-dimensional digital map of soft and hard tissue.

There aren’t many groups doing this right now, but this is another upcoming attraction for dentistry. What’s done now is usually you get a standard dental impression and you make a model of the mouth and then you can scan that model.

This adds an extra step. It adds time. At every step of the journey, there is a degree of uncertainty. So you get less and less precision as you make copies of copies. But this is how we obtain the three-dimensional digital image that allows the local or remote construction of the 3D printed device.

Dentists are good at thinking in both the positive dimension and the negative dimension – creating a negative model that creates a mold that I can then fill in, and that becomes the positive. And that always adds to my level of appreciation for what dentists do – being able to think in these multi-dimensional terms, while even being able to work with a mirror and do the right thing in the right place.

Where do you see your next research on this subject?

Sorensen: I think the next steps would be to test the biocompatibility of these materials and ensure that they are safe for clinical application. And then also developing a wider range of materials with not only strong mechanical properties, but also very flexible materials, with less rigidity.

You may want to have softer and more flexible materials on the rubber surface. The next step would be to identify and develop materials for these applications as well. What’s interesting is that with an inkjet 3D printer, you can actually mix different materials with more extreme property differences to achieve an intermediate property.

So you can take something really stiff and strong and mix it with something a bit more flexible. This is achievable because the droplets delivered by 3D inkjet printers are picoliter-sized. Thus, you can create materials with graded functional properties that behave more similarly to biological tissues.

Stansbury: Yeah, what I see coming is the ability to do both the aesthetic and the mechanical mix with all kinds of different technical aspects. So we can make something stiff in one direction, but flexible in the other, which, again, is not feasible in any of the other current ways of making materials.

It just opens many doors where design engineering, materials science and 3D printing processing can all come together and have only patient devices that are cost effective, developed quickly and offer the best materials and performance available. If we can do that, then we will have solved a lot of problems. It’s very exciting.

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