Clear aligners use a series of custom-made, virtually invisible trays to gradually shift your teeth into their desired positions. The trays are made of a smooth, BPA-free plastic that is comfortable to wear and won’t irritate your mouth like traditional metal braces. Each set of aligners is worn for about two weeks before being replaced with the next set in the series. You will need to wear your aligners for at least 22 hours a day to ensure optimal results.