How are clear aligners made?
Many people are surprised to learn that clear aligners are not 3D printed. But the process of making clear aligners does involve 3D printing. The flowchart below outlines the four general steps involved in the process of making clear orthodontic aligners.
All clear aligners are made using some version of these four basic steps. However, there are different technologies and methodologies that can be used at each step that will affect the quality and accuracy of the final aligner product. In this article, we’ll explore each step in a little more detail.
The patient is a critical part of the process of making aligners. It is the patient that should ultimately decide that clear aligners are the best treatment method for them (more on that here). For some of the low-cost, at-home treatment options the patient must make an accurate impression of their own teeth (not recommended). The treatment design should marry patient priorities and desires with sound orthodontic principles.
STEP 1: IMPRESSION
The axiom “garbage in, garbage out” definitely applies here. The impression is the input data upon which the entire process hinges. If the impression is not accurate, the results will be compromised and the patient will likely experience discomfort throughout the treatment.
The two most commonly used methods of taking impressions are:
- A physical impression using dental "putty"
- A digital scan using an intraoral scanner (a scanner that goes in your mouth)
In the age of digital dentistry, a digital scan is the preferable method. It is a much more comfortable experience for the patient. It is safe. It is accurate (although not all scanners are created equal). Digital scan files can be transmitted to a laboratory or to a colleague for review with the click of a button (versus a physical impression that has to be packaged and mailed). For a more in-depth analysis of the pros and cons of each method, read this article.
STEP 2: DESIGN
One critical area of divergence in the quality of clear aligners is in the design process. Orthodontists are experts that have extensive, specific training in the movement of teeth. General dentists may be certified by clear aligner brands to administer clear aligner treatment, but their actual expertise in this area can vary significantly. Even those general dentists that do have significant additional training in this field are not as qualified as is an orthodontist. For this reason, we caution against treatment modalities where there is not an orthodontist overseeing the treatment design.
There are three critical contributors to a successful treatment design:
- The patient: It is the responsibility of the patient to clearly express their priorities and expectations. Not all patients have the same treatment goals. Some want perfect teeth and are willing to endure any amount of time, discomfort, and expense to get them. Others just want a specific issue corrected and place higher emphasis on some combination of speed, convenience, comfort and/or cost.
- The treating doctor: Though an orthodontist is an expert in the biological and anatomical aspects of teeth movement, they are often not experts in the software platforms upon which the treatment is set up. That is done by the lab technician. The treating doctor must provide instructions to the lab technician that reflect the priorities of the patient while also following sound orthodontic principles.
- The lab technician: The lab technician executes the design of the treatment inside the software environment according the instructions of the prescribing doctor. Software parameters help to ensure that only realistic teeth movements and timelines can be inputted into the design.
STEP 3: MODEL
This is the part of the process that many people are unaware exists. Clear aligners themselves are not 3D printed. Instead, a model of the teeth is 3D printed for each stage of the treatment. This is where a lot of the expense of clear aligner manufacturing is incurred. The equipment, material (resin) and time required to print these models is costly.
As with every other step in the process, the accuracy of the 3D printers and the quality of the resins that are used will impact the quality of the aligners.
NOTE: Technological advancements continue to drive efficiencies in the delivery of affordable orthodontic care. The industry is pursuing technology that will allows for aligners to be directly 3D printed, bypassing the need to 3D print models of the teeth at each stage. When this breakthrough is achieved, we should see a further reduction in the cost of making clear aligners.
STEP 4: FABRICATION
Once the models are printed, the aligners can be fabricated. A sheet of thin thermoplastic material is heated to forming temperature then applied to the mold to take the shape of the teeth. After cooling and hardening, the aligners are trimmed and the edges are buffed smooth. These processes can be done by hand or by automated industrial machines.
In the fabrication process, the thermoplastic material matters. Essix and Zendura are two of the most used thermoplastic material brands in the United States, but there are many other options available in the market. The best thermoplastics materials provide an optimal balance of sustained moving force and comfort for the wearer, clarity, and are be BPA-free. Generally, increased comfort comes from a softer material that provides less sustained moving force. Greater sustained moving force is achieved by harder and thicker materials that afford the wearer less comfort.
Technological advancements have made the process of making clear aligners more efficient and accurate than ever. Though all manufacturing processes follow the same basic steps, the different approaches at each step will have a significant impact on the quality of the finished product. We caution consumers against simply choosing the lowest cost option. Consumers should ask the following questions about how their aligners are made:
- How reliable and accurate is the impression method?
- Is an orthodontist involved in the treatment design?
- How accurate are the 3D printers that print the teeth models?
- Are the aligners made with premium thermoplastic materials?