You should brush your Invisalign trays every time you brush your teeth, but you must avoid using standard toothpaste. Most toothpastes contain abrasive ingredients designed to scrub tough tooth enamel, but these can create microscopic scratches on the relatively soft plastic of your aligners. These scratches make the trays look cloudy and provide tiny hiding spots for bacteria, which causes the trays to smell bad. Instead, use a soft-bristled toothbrush and a small amount of clear, fragrance-free dish soap or specialized cleaning crystals. Gently scrubbing both the inside and outside of the trays ensures that saliva and plaque are removed, keeping your aligners crystal clear and your breath fresh throughout the entire duration of your treatment.