Invisalign aligners are made through a multi-step process that combines digital scanning, 3D printing, and thermoforming. Your teeth are never directly molded in the traditional sense. Instead, a digital model of your mouth is used to 3D-print a physical mold for each stage of treatment, and a medical-grade plastic sheet is heated and pressed over that mold to create each custom tray. Align Technology has manufactured over 2.4 billion aligners worldwide using this process.
Digital Scanning and Treatment Planning
The process starts at your orthodontist’s office with a 3D scan of your teeth. A small handheld scanner captures thousands of images of your mouth and stitches them together into a precise digital model. This replaces the old method of biting into a tray of putty to make a physical impression.
That digital model is uploaded to Align Technology’s proprietary software, ClinCheck, which maps out the entire treatment plan before a single aligner is manufactured. The software uses AI-based segmentation to isolate each individual tooth in the scan, then calculates exactly how each tooth needs to move across every stage of treatment. These movements include extrusion and intrusion (pushing teeth up or down), translation (shifting them side to side or front to back), rotation, and changes in angulation and inclination. The software calculates each movement using a center of rotation placed 1 to 2 millimeters from where the tooth meets the gumline.
Your orthodontist reviews this virtual plan, adjusts it, and approves it before manufacturing begins. The final plan specifies every incremental position your teeth will pass through, which determines how many aligners you’ll need and what each one looks like.
The Material: SmartTrack Plastic
Since 2013, Invisalign aligners have been made from a material called SmartTrack, a multi-layer thermoplastic polyurethane. It replaced an earlier material called EX30 that had been in use since Invisalign’s launch. SmartTrack delivers more consistent force on your teeth, has greater elasticity, and fits more precisely than its predecessor. It’s also chemically stable, meaning it doesn’t break down or leach compounds in your mouth over the course of a wear cycle.
The material is classified as medical-grade and tested for biocompatibility. In practical terms, this is what gives Invisalign its characteristic feel: firm enough to push teeth but flexible enough to snap on and off without cracking.
3D Printing the Molds
Here’s what surprises most people: the aligners themselves are not 3D printed. Instead, a physical mold of your teeth is 3D printed for each stage of treatment. If your plan calls for 20 sets of aligners, 20 individual molds are printed, each one representing a slightly different tooth position along the path from your starting alignment to your final result.
These molds are created using a process called vat polymerization, most commonly stereolithography (SLA). A liquid resin made of light-sensitive monomers and oligomers sits in a vat. A UV laser traces each cross-section of the mold onto the resin’s surface, hardening it one ultra-thin layer at a time. The object builds vertically, layer by layer, from a digital file. When the laser hits the resin, it triggers a chemical reaction called chain radical polymerization, where the liquid molecules link together into a solid polymer. The result is a highly accurate replica of your teeth at that specific treatment stage.
Align Technology operates manufacturing facilities in Juarez, Mexico, Ziyang, China, and a newer plant in Wroclaw, Poland. These facilities run this printing process at enormous scale across thousands of patients simultaneously.
Thermoforming: Shaping the Aligner
Once the molds are printed, the actual aligner trays are formed through thermoforming. A flat sheet of SmartTrack plastic is heated until it becomes soft and pliable. The heated sheet is then pressed over the 3D-printed mold of your teeth using either vacuum suction or positive air pressure, forcing the plastic to conform tightly to every contour of the mold. In positive-pressure thermoforming, the sheet is heated to around 220°C for roughly 25 seconds, then formed under 4 bars of pressure and held for 35 seconds. Cooling takes another 60 to 90 seconds under pressure until the plastic is fully stabilized and retains its shape permanently.
After cooling, the excess plastic extending beyond the gumline is trimmed away. This trimming follows a digitally mapped cutting path customized to your gum contours, so each aligner’s edges sit precisely along your gumline rather than cutting into your gums or stopping short.
Quality Checks and Shipping
Each finished aligner is inspected, labeled by stage number, and packaged in sequence. The full set of trays for your treatment (or a batch of them, depending on how many stages your plan involves) ships directly to your orthodontist’s office.
From the moment your scan is uploaded, the entire manufacturing and shipping process typically takes two to four weeks. Some patients report receiving trays in as little as two weeks, while the more common timeline is closer to three or four weeks. The variation depends on your location relative to the manufacturing facility, the complexity of your case, and how quickly your orthodontist approves the ClinCheck plan.
Why the Process Matters for Your Treatment
The precision of this manufacturing chain is what allows Invisalign to make aligners that move teeth in controlled increments, usually around 0.25 millimeters per tray. Each aligner is intentionally shaped to be slightly “ahead” of where your teeth currently sit, creating gentle, sustained pressure that nudges them into position over one to two weeks of wear. When one tray stops feeling tight, that’s your signal to move to the next one in the sequence.
Small features called attachments, which are tooth-colored bumps bonded directly to certain teeth at your orthodontist’s office, work together with the aligner shape to generate more complex movements like rotation or vertical shifts. The placement of these attachments is also determined during the digital planning phase and mapped onto your treatment plan before manufacturing begins.