Clear aligners, such as Invisalign, are a series of customized, removable, nearly invisible trays that straighten your teeth. Since they are removable, you can eat and drink what you want while in treatment, and you can brush and floss more easily. Aligners need to be worn 22 hours per day in order to be effective. Clear aligners work best for mild to moderate orthodontic problems and may not be an option if more serious treatment is required.