Dental 3D Printing – Additive Manufacturing Applications and Market Processes

2021-05-12

Lee-Bath Nelson  

HP 3D printed dental patterns for clear aligners Hannover Messe 2019 photo by Tessa Blokland

When it comes to additive manufacturing (AM), adoption rates are highly dependent on the application and industry. In the dental industry AM is embraced and 3D printed applications abound. I spoke with Ron Ellenbogen, the Dental Product Line Director at Stratasys, who is a fountain of knowledge about the industry, applications, and the historical processes that brought us so far. My goal is to get a better understanding of the AM dental market and figure out what prompted the relatively widespread adoption in order to try and single out additional industries with similar starting conditions where AM adoption can speed up.

Aligned and Clear

One of the important starting conditions in the dental market, says Ellenbogen, is that a digital workflow was already present in order to mill crowns. Even though the impressions were taken in the old fashioned way, physically not digitally, they were converted to a digital file that could be fed to a digital milling process. “This was a ripe ground for additional digital processed such as oral scanning and 3D printing to enter into the dental work flow” he adds. That’s exactly what happened. Oral scanning entered and enabled 3D printing of several dental restorations and aids (more on that below). Ellenbogen notes that COVID-19 accelerated these processes as handling traditional impressions (the ones you bite into) has become more expensive and everyone (customers, dentists, and lab technicians) became reluctant to handle them.

In parallel, Align Technology had the idea to introduce clear aligners that are produced by stretching them on 3D printed models (this method is called vacuum forming). To achieve this they worked closely with 3D Systems to create a 3D printer/resin combination suited for aligners and that close collaboration continues to this day. In fact, I believe Align is the number 1 customer of 3D Systems, which according to their 2019 annual report, accounted for 11% of their total revenues. This collaboration and Align’s approach were a breakthrough as it enabled dentists to leverage their dental scanning and offer orthodontic services even if they are a GP (general practitioner), not an Orthodontist. This was the original positioning – added value services for GPs – but later the Orthodontists also started using it and today, on average, a US Orthodontist orders 7x more aligners from Align than a US Dental GP trained on its system. In their latest annual report (2020), Align Technology say over 200,000 dentists are trained to use its end to end solution and over 9.6mm people have been treat with Invisalign so far. At an average of 30 aligners per person that means that well over a quarter of a billion (yes, that’s a billion with a b) 3D printed aligner forms have been made by Align. Recently Align announced it will add a 3rd plant in Poland and also mentioned that it’s current production capacity is 700k aligners a day. Now that’s high volume!

HP bed of dental patterns Hannover Messe 2019 photo by Tessa Blokland

Enter the Competition

Align’s high gross margin (over 70%) did not go unnoticed and soon competitors entered. Since 3D printing is used for the mold and not for the aligner itself (the clear aligner is stretched over the mold to produce its final shape), different AM technologies can be used – in fact, in the Invisalign in the photo below you can see the 3D printed layers so clearly the finish on the pattern is not so crucial. ClearCorrect, which also works with dentist, like Align, uses Stratasys 3D printers. Ellenbogen also said that “Stratasys has a set of solutions for the clear aligner industry for both large producers and for orthodontic labs who would like to add clear aligners to their product portfolio.” SmileDirect Club worked with HP to take the next step and offer teeth alignment services direct to the consumer. It has a collaboration with the CVS pharmacy chain to offer this service. Customers come in and have an oral scan performed by a technician. Software generates a plan of aligners and a dentist only has to review the plan – takes much less time than if a dentist does everything so the dentist’s throughput is much higher. SmileDirect aims to fix simple cases of misalignment for people that have stopped wearing their retainer, for example. Complex cases are referred to a dentist. Additional competitors include Candid (who is using Carbon‘s L1 3D printers), and Byte (who send you a traditional impression kit to your home rather than using an oral scan). These competitors caused prices to come down (though Align still maintains it over 70% gross margin) and highly expanded the availability and use of clear aligners. These mass quantities are possible thanks to automation and an end-to-end solution that is offered to the consumer (with or without the involvement of his/her personal dentist). Carbon partnered with 3Shape to streamline their offered workflow and include serialization in the workflow. It seems that the clear aligner category is, by far, responsible for the most 3D prints of all applications and that this application is poised to continue onwards and upwards with a “set of solutions”, as Stratasys’ Ellenbogen calls it, ready to be easily deployed.

Invisalign_tray with 3D printing layers of pattern visible

Dental Restoration

The other main category for 3D printing is the dental restoration workflow. This category includes dentures but not only. Ellenbogen specified several other application areas where Stratasys is active: test models to check fit, removable partial dentures (several teeth in a denture held on other teeth with a metal structure), surgical guides for teeth implants, and try ins for complex restorations. Let’s start with the most obvious: dentures. Ellenbogen explained that milling a single denture plate takes a long time which comes with a high opportunity cost: the same machine can mill tens of crowns in that time and those would bring in 10x the revenue from 1 denture… Enter 3D printing. “It makes sense as the size of the dentures is relatively small but possibly too big for effective milling making milling expensive. Also, the basic acrylic materials used for dentures are very similar to the acrylic used for 3D printing – it’s always good when materials can be closely matched.” he says. DLP is an appropriate AM technology for dentures because of its smooth finish and high throughput so it is no surprise that the switch to 3D printing happened recently, in 2019, led by NextDent (a 3D Systems material company) and DENTCA (a Mitsui company offering dentures) and followed by other companies using Carbon and Kulzer (also a Mitsui Chemicals company) 3D printers.

Removable partial dentures have the denture part (several teeth, not an entire upper or lower bite, sometimes the missing teeth are on both left and right sides of the mouth) but also the metal construction holding it together. The denture part we talked about and for the metal piece a 3D printed pattern can be used with investment casting. Because of its size (approximately the size of the jaw), the pattern is 3D printed in acrylic rather than wax and that pattern is used for investment casting (where the single use mold is formed around the pattern which is melted in the casting process). Another widely used category, that accounts for a large part of the printing volume in many dental labs, is test models used to check fit (in complicated cases they are called try ins). Here, rather than milling a crown or bridge right away, you first 3D print a version to be checked in the patient’s mouth and only if it fits is the milling done. The last category is surgical guides which help guide the dentist to the best location for implant surgery both in complex multi tooth surgeries and in surgeries where the dentist is less experienced. Ellenbogen believes one of Stratasys’ important advantages is that it can handle a mixed tray (bed) of different application each done in a different material but still on the same printer tray. This allows the lab to utilize its capacity efficiently and do large runs overnight, for example.

Stratasys_dental_materials_dental_model_natural2

Clearly the adoption in the dental market is expanding in both applications and quantities and it is clear from the explanations above how conditions were ripe for it. Still, it took visionary founders and executives to seize the opportunity and to realize that they needed to provide a holistic end-to-end solution (which was enabled by Align’s acquisition of another visionary company: oral scanning company Cadent). So, what is the next industry that is ripe for this kind of mass disruption? Could it be the sneaker industry? How about the broken bones (casts) business? The problem with both of those is that they do not have a 20 year old digital workflow. However, I can think of several digital by nature industries, like the semiconductor business for example. Are there 3D printing applications for chip production? Could 3D printing help in the next major supply chain failure in that industry? That’s a whole other post – stay tuned.

For more insights and information follow us on LinkedIn or subscribe to our newsletter for weekly updates. Pictures: top 2 photos by LEO Lane‘s Tessa Blokland from the HP booth at Hannover Messe 2019; InvisAlign tray with visible layers; and a dental implant planning aid 3D printed with a Stratasys dental material.

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