You should keep the trays so that you can 'top up'the bleaching effect in the future. Please note, 'topping up' the effect is not harmful and is usually rapid in action. Keep the models in case you lose or damage the trays as we can make a duplicate set easily and less expensively.
Do not put your bleaching trays in very hot water as they will permanently distort. Avoid exposing the bleaching temperature to high temperatures (avoid leaving in your car) as the carbamide peroxide gel will degrade much more quickly and lose its effectiveness. We recommend keeping the gel in the fridge (not freezer) where it will last for up to 2 years.