An Inevitable Paradigm Shift?

Inside Dental Technology (IDT): Why is multijet or polyjet 3D printing such a promising development?

John Madden, CDT: We are working to utilize this technology on denture and partial denture fabrication in a modern context at scale. As a profession, we need to figure out how to make 6 million arches per year in the United States, faster, and with declining numbers of dental technicians. Being able to do multicolor printing and introduce color information into the design stage, rather than designing in grayscale, could eliminate some steps of the fabrication workflow to improve speed and efficiency.

IDT: How will that be done?

Madden: Design and assembly are the keys. The technology continues to progress, but it is not really set up to be done at a large scale. So, the questions we are asking now are: What are all the components? How do we assemble them all? How do we maximize efficiency in the process? Currently, we make a lot of relational parts. The large majority of 3D printing in dentistry is still just models, not actual parts for prosthetics. If we want to fabricate prosthetics at greater scale with fewer and fewer technicians, one thing we need to do is eliminate all of the secondary models that are being used. We want to take all the components of a hybrid denture and assemble them without any relational model. The crux of it is the idea that we now have the ability to design with such high precision and manufacture with such accuracy and predictability that we should not need a secondary model. However, our tools, techniques, and methods are not built for doing that. All of the implant components and partial denture components that we have are built for use with check models. If we want to produce hundreds per day and tens of thousands per year, however, eliminating those steps and unnecessary pieces will be significantly impactful.

IDT: How do you do that?

Madden: It will involve software, assembly methods, and everything else. I cannot disclose exactly what we are working on at the university, but some of the partial denture work I have done previously involved determining how to assemble dentures without needing a cast. We could 3D print metal frameworks or mill acetal frameworks, but that was the only step that could be completed digitally. We could not assemble all the pieces without a model. Of course, newer software allows us to make a split-piece design and assemble, but another big problem we ran into was stress-relieving clasp assemblies. Nobody had a solution for digitally fabricating wrought wires—flexible wrought-wire clasps, for example, are necessary for 30% to 40% of chrome framework cases. To address this issue, the university created a patented clasp library, where the wrought-wire clasp could be metal injection molded and added as a design feature in the software, and it has the relational element such that it can be assembled without a model. You basically print the base, print the teeth, have the clasp as a library object that is metal injection molded, and you assemble them like LEGO^® blocks. That is more efficient than the current process of taking the framework, soldering on a wrought-wire cusp that is hand-bent, processing to a stone model, and setting the teeth back to a stone model. Anything that can eliminate some of the back and forth between analog and digital processes in partial dentures is a step in the right direction. If you imagine a world where the process is completely digital, though, there are still a lot of missing tools, and most of them involve assembling metal parts.

IDT: What are some other processes for which solutions like that could help in the future?

Madden: Realistically, our industry is driven by the materials manufacturing business, so we have a tendency to lean toward materials solutions. We are looking partly at reconceptualizing the prosthetics for 3D printing technology, but the technology really has not settled. Most of what we have seen in the past 3 years are materials solutions for partial dentures or same-day hybrids: newer, stronger material; newer, stronger material; newer, stronger material. We have constant iterations of materials, and they are moderately successful. They are incrementally getting better. However, what has not happened is reconceptualizing the entire prosthetic. A good example of a truly impactful solution was when we started to do direct-to-multi-unit hybrids, without titanium bases. That is reconceptualizing the prosthetic. That is saying, "We have the technology now to do this accurately enough that we can let go of this piece and start treating this prosthetic differently." That same thought process needs to occur in partial dentures; it is just more complex. Our solutions in the partial denture space, especially with acrylic partial dentures, have been mostly throwing materials at the wall and seeing what sticks. We keep developing flexible material options even though flexible partials account for only approximately 10% of the partial denture market. We need to look at partial dentures completely differently and realize that we can make them in totally different ways that were not possible previously. How will we do that? When I look at solutions with a lot of finesse, I am looking less at the material options and more at how people repackage the prosthetic to which it applies. Most of that innovation has been in the hybrid space, because that is where the glitter is, but really, it probably needs to go back into those bread-and-butter objects that we make millions of in the United States every year.

IDT: Are any other new innovations catching your eye?

Madden: What is really cool to me is that, from a historical standpoint, we are at the confluence of a lot of really big changes not just in dentistry but in medical technology overall. When you add them together, that is really when they become interesting. One thing everyone is interested in is artificial intelligence (AI) design; how do we move into a world where AI design for full-arch prosthetics is useful? When you start to unpack that problem, and you consider what is happening in the hardware space, you realize these are two pieces of the puzzle that will fuel each other. I envision multicolor printing and AI-enhanced design feeding off each other to the extreme, like pouring gasoline on a fire. The implications of full-color printing will lead to major changes in our design software. Most of our design software is grayscale, and we are limited by that. Adding all this color information really calls for an entire breaking down and rebuilding of our design systems.

IDT: How about integrating all of the different diagnostic data that can now be acquired—are we able to fully capitalize on the so-called virtual patient yet?

Madden: This is a much bigger discussion and almost its own area of innovation: how we collect, organize, distribute, and democratize patient records. That is a massive topic. Wouldn't it be great if we had a complete patient record that included a face scan, a jaw motion file, patient history, shade data, etc, and all these things were aligned, usable, organized, and accessible? That does not happen right now. All of those single pieces are available—albeit not for every patient. It comes down to whether we are smart enough as an industry to organize it and make it accessible when it is needed. To me, that whole argument really revolves around clinicians and regulatory bodies to say, "This is what a modern patient record looks like, this is how we will store all this data to make it safe, and then this is how we will allow access to it to make it useful." They also must decide who owns it; does the patient own this record? That is the trend. Who owns it and who has access to it? Redefining that is a seismic shift on its own. We are still really disorganized. How will we repackage our abilities, whether by changing billing coding, changing access to records, changing organization, or changing the way we store and break down a prosthetic?

For the past 10 years, I have been storing denture files for patients to reprint when needed. Imagine that across all the records and all the prosthetics. Imagine the patient owning those records. But any time we restructure or reorganize our new abilities and put them into context to make them accessible and productive, it requires a major change. I do see 3D printing bringing more convenience into the world of dentistry. Our first pass at conceptualizing how that was going to be useful was perhaps a bit shortsighted. Now, how will we package it to actually make it useful to humanity? We have 6 million denture arches that need to be fabricated in the United States each year, and with each year that passes, we have fewer technicians to make them. How will we make up that shortage and bring domestic production back into the United States? It takes a lot of organization, harnessing of ability, and repackaging in a way that makes sense.

John Madden, CDT
Owner
John Madden Prosthetics
Minneapolis, Minnesota