The length of time Invisalign treatment takes is dependent on the individual and the condition of your teethits something your doctor will need to determine during a consultation. Most adults using Invisalign will need to have aligners in for about 12 months, and teenagers may need to have them in for a few months longer to achieve the best results. That being said, if you have only minor adjustments to be made in your teeth, you may have treatment for a shorter period of time.