These home teeth whitening trays give you a custom fit, just like at the dentist, even though when you order them, they come in one-size-fits-all. The special material conforms to your teeth for a more even and effective application of the teeth whitening gel.
They are molded by dipping them in hot water and then placing them in the mouth to form a precise mold of the teeth. For this reason, these whitening trays are referred to as “boil-in-bite” mouth trays. The special blend of polymers has a very low molding temperature so there is no need to use extremely hot boiling water.
Boil-n-bite, or thermo-forming, trays such as these can be a little tricky form. If you don’t follow the instructions very carefully, you could end up with an unusable lump of material.