Application Spotlight: 3D Printing for Digital Dentistry & Clear Aligner Manufacturing

08 August 2019
clear aligners

Digital dentistry — the introduction of digital technologies into the dental practice — is transforming the dental industry. One of the key technologies driving this transformation is 3D printing.  
3D printing has many applications in the dental industry, including bridge models, surgical guides and dentures. However, clear aligner manufacturing is one of the most common uses of dental 3D printing today.  
According to SmarTech Analysis, clear aligners are “perhaps the single highest volume application for 3D printing technologies in the world today.”
But how does 3D printing fit into clear aligner manufacturing? 
To answer that question, today we’ll be exploring the benefits of 3D printing for clear aligners, whilst looking at how dental professionals and labs integrate the technology into their digital dentistry workflows. 
Take a look at the other applications covered in this series:
3D Printing for Heat Exchangers
3D Printing for Bearings
3D Printing for Bike Manufacturing
3D Printing for Medical Implants
3D-Printed Rockets and the Future of Spacecraft Manufacturing
3D Printing for Footwear Manufacturing
3D Printing for Electronic Components
3D Printing in the Rail Industry
3D-Printed Eyewear
3D Printing for End-Part Production
3D printing for Brackets
3D Printing for Turbine Parts
How 3D Printing Enables Better-Performing Hydraulic Components
How 3D Printing Supports Innovation in the Nuclear Power Industry

What are clear aligners?  

3D printed clear aligner moulds
[Image credit: Formlabs]

Clear aligners are dental devices used to adjust and straighten teeth. Aligners offer an effective alternative to metal braces because unlike traditional braces, aligners are virtually invisible and can be removed when users eat and brush their teeth. 
The use of digital technologies to manufacture clear aligners is a perfect example of digital dentistry in action. The process typically begins with an orthodontist capturing an impression of a patient’s dentition with the help of a 3D intraoral scanner.
After scanning the patient’s teeth, the digital scans are used to design the desired position of the teeth. Once the final position has been determined, an orthodontist will plan the incremental stages between the current and desired teeth positions.  
Moving teeth is a complex process requiring several different aligners to be switched as the treatment progresses. The number of incremental models can range between 5 and 30 (on average, 6-10).
To create each aligner, orthodontists first need to produce moulds. These are then used in a moulding process called thermoforming. 
And this is where 3D printing comes in. 
It is estimated that the majority of clear aligners are currently produced using 3D-printed moulds. The key technologies enabling this are Stereolithography (SLA) and Material Jetting thanks to their high speed and accuracy. In addition to these resin-based processes, HP’s powder-based technology, Multi Jet Fusion, is also gaining traction. 

The benefits of 3D printing for clear aligners 

Patient-specific solutions 

Clear aligners are inherently individualised products. A set of aligners is custom-made to fit a patient, with each aligner being slightly different from the other.
This need for a high level of customisation requires a very flexible technology to make customisation viable. 
3D printing is the only technology that enables dental professionals to customise clear aligners cost-effectively. 
Unlike the milling process, which has been used in dental practice to create moulds, 3D printing doesn’t require expensive setup and tools. This means that 3D printing can produce highly complex aligner moulds without added cost. 

Mass customisation 

Traditionally, clear aligner moulds have been fabricated using a combination of milling and manual processes like trimming, resulting in a time-consuming and labour-intensive process. 3D printing accelerates the process by enabling a large batch of custom moulds to be produced directly from patients’ digital scans. 
For example, Stratasys claims that its J700 Dental 3D printer can produce up to 400 clear aligners per day. HP has gone even further, stating that its new customer, SmileDirectClub, will be able to produce 50,000 unique moulds per day using 49 HP Jet Fusion 3D printers running 24/7. This is roughly equal to 1,020 moulds per day for one printer alone. 
No other technology would be able to create that amount of customised moulds in such a fast and cost-effective way, other than 3D printing. 

Producing clear aligners at the point of care

Dental 3D printing enables orthodontists to produce aligner moulds in-office, saving both time and money. 
In one common scenario, patient intraoral scans are sent to the dental lab for modelling and treatment planning, then high-resolution digital files are sent to the dentist’s office where the staff will 3D print the moulds and fabricate the aligners. 
By taking this approach, a dentist can begin treatment in a matter of days instead of weeks. 
Furthermore, thanks to this digital workflow, aligners can be replaced much faster in the event that they are lost by a patient. With an in-office lab, the staff can use the digital file of the lost aligner, 3D print a mould and then quickly cast the new one — a process that can be done within several hours. 

Examples of 3D printing for clear aligners 


DynaFlex: Expanding into the clear aligner market with  3D printing

Polyjet 3D-printed clear aligner moulds
Clear aligner models 3D printed using Polyjet technology [Image credit: DynaFlex]

DynaFlex is a manufacturing company that specialises in dental-related markets like orthodontic devices and dental office solutions. 
With the growing business opportunity for clear aligners, DynaFlex wanted to expand into that market, but needed a technology to support the company’s growth in that area.
3D printing offered an ideal solution, offering a high level of productivity and automation — exactly what was needed for Dynaflex’s digital workflows. 
The company used Stratasys’ J700 Dental 3D printer, developed specifically for the production of clear aligners. Based on PolyJet technology, the J700 Dental 3D Printer jets layers of liquid photopolymer onto a build tray and cures them with UV light. Fully cured dental moulds can be handled and used immediately without additional post-curing. 
According to DynaFlex, the J700 Dental can print roughly 55 moulds, nested on a build plate, in three hours. The company plans to produce over 1,000 moulds a day and is looking to purchase two additional 3D printers. With dental 3D printing on board, DynaFlex is now well-positioned to scale its clear aligner business.  

Cranston Orthodontics: 3D printing clear aligner moulds in-office

Dental moulds 3D-printed on EnvisionTec’s desktop 3D printer [Image credit: EnvisionTec]

US-based orthodontic practice office, Cranston Orthodontics, has adopted 3D printing to produce clear aligners in-house. With 3D printing, the orthodontists at Cranston Orthodontics can cut turnaround times for clear aligners, producing the moulds as fast as in one day.
To achieve this, the company uses desktop 3D printers from EnvisionTec in combination with a range of materials designed specifically for dental and orthodontic use. 
The process begins with making intraoral scans, which are then prepared for production using dedicated software and sent to a 3D printer.
The in-office, desktop 3D printer used by the company can print a batch of up to 7 dental moulds with EnvisionTec’s E-Model material, developed specifically for the production of dental and orthodontic models. After some cleaning and drying, the moulds are thermoformed, finished by hand and ready for use.
With its 3D-printed moulds, Cranston Orthodontics says it is able to produce clear aligners with high detail and accuracy, resulting in a better fit for patients and, ultimately, a better service. 

SmileDirectClub: Making clear aligners more affordable with 3D printing 

Clear aligners made by SmileDirectClub
[Image credit: SmileDirectClub]

Founded in 2014, SmileDirectClub is a US startup with the goal of providing a more cost-effective solution to clear aligners. The company chose 3D printing as an affordable way to manufacture custom invisible aligner moulds. 
The 3D printing process begins with customers taking impressions of their own teeth using a home impression kit or making intraoral scans at a dedicated SmileShop centre. 
A dental professional will then review the impressions or scans and create a treatment plan. Once confirmed, the company 3D prints and sends the customer their set of aligners. 
SmileDirectClub has had enormous success with this unique service, with more than 300,000 people already benefiting from a more affordable teeth-straightening solution.
Following this success, SmileDirectClub has recently partnered with HP to expand its reach of inexpensive, personalised teeth-straightening treatments. The company plans to install 49 HP Jet Fusion 3D printing systems to produce over 50,000 unique moulds a day. This amounts to an estimated 20 million moulds over the next 12 months — an enormous business opportunity.
By leveraging the benefits of remote teeth-straightening treatment and HP’s 3D printing technology, SmileDirectClub aims to give its customer a chance to achieve a straighter smile at a cost that is up to 60% less than traditional invisible aligners.

3D printing clear aligners directly? 

As the clear aligner market continues to grow, dental companies are pushed to innovate in order to remain competitive. One way to reduce costs and improve operations is by reducing the production of aligners to a one-step process: direct 3D printing. 
A one-step production process would reduce factory capital costs with the potential to significantly increase throughput. 
Align Technology, the largest producer of clear aligners, well-known under the Invisalign brand, says that direct 3D printing of aligners is an area they are actively working on and investing in.
According to a recent SmarTech’s research into the dental 3D printing market, direct 3D printing of clear aligners could be just around the corner. 

a chart representing the growth of 3D printing for clear aligners
[Image credit: SmarTech Analysis]

The chart above shows that the dental market will reach an inflection point for directly 3D-printed aligners in the next 5 years. Much of this progress will be attributed to the development of the next generation of dental 3D printing technologies based on photopolymerisation techniques. 
Clearly, 3D printing is taking the orthodontics industry by storm. The technology offers a cost-effective and mass-production option of aligner moulds. Furthermore, it has brought the mass customisation to the level unseen in any other industry. 
Ultimately, advancements in 3D printing technology will allow orthodontic professionals and clear aligner manufacturers to 3D print aligners directly, decreasing costs and turnaround times, while further improving the quality of dental care. 
In our next article, we’ll be taking a look at 3D printing in the medical industry, and specifically for implants. Stay tuned!


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