Dr. Martens also offers Invisalign®, a clear teeth-straightening system that allows crooked teeth to straighten nearly invisibly. Dr. Martens will fit you for custom plastic trays, called aligners. Each set of aligners is worn for two weeks before moving on to the next set. The process is repeated until your teeth are straight. You will then be provided with retainers to help your teeth remain straight as well as take-home whitening, which is provided at no additional charge.