Invisalign is a type of orthodontic treatment that uses clear, removable aligners(trays) that fit over the teeth like retainers to straighten them out over a specified treatment time. They are made of a flexible thermoplastic called SmartTrack. Your Orthodontist will use 3D computer imaging technology to create a treatment plan from the initial position of your teeth to their final desired position. A set of aligners are typically worn for 1-2 weeks at a time. The trays are manufactured so that the teeth will move in small increments. When you put a new aligner in, the tray itself is slightly straighter than your teeth are. This puts pressure on your teeth, so that over the course of the week, they will shift to match the aligner. Compliance is key, for they are to be work for 22 hours a day.