Hello, Mold may have spores that are difficult to remove. You need to soak these in denture cleaners. Brushing alone is not adequate. For resistant fungal infections with denture patients, soaking the appliance in bleach with a one part bleach and 10 parts water ratio is recommended for 10 minutes. Boiling can be required. A Nystatin rinse may be prescribed by your dentist, if necessary. Fungal infections can develop in your mouth. I recommend that you check with the Invisalign manufacturer or you dentist before using bleach on your trays. Trays are made from a custom impression of your mouth. Your mouth changes with time as your skull continues to grow throughout your life. These may not fit adequately. Are you up to date on your dental cleanings? Consider scheduling a visit and bringing your cleaned tray to see if the fit will allow you to continue treatment. Bad breath often indicates gingivitis and requires a dental cleaning to help eliminate this condition and avoid progression to advanced periodontal disease. Other serious dental conditions or diseases can affect your breath. Your dentist will assist you will a diagnosis at your dental recall visit. thank you for your inquiry.