These clear aligners are designed using a mold of your teeth. A lab technician will apply layers of a photo-sensitive liquid resin to this custom mold. Next, the technician will expose this resin to a laser, curing it into a hard, yet flexible, thermoplastic. This plastic is called SmartTrack®, and it was created exclusively for Invisalign treatment. It’s FDA-approved and contains no BPA, BPS, latex, or gluten.