Laser teeth whitening theory: A bleaching solution is applied to the surface of the teeth, and a laser light is directed at the mouth. The solution is activated by a powerful heat from the laser and subsequently brightens the teeth,As the laser illuminates the tooth ,darker colored parts of the tooth absorb the laser rather than reflect it. This absorbed light is converted into heat energy. Areas of the tooth like the pulp chamber and dentin are the darkest so they heat up the most. Teeth typically become at least six to ten shades whiter.