Laser radiation tooth bleaching

The study describes the preclinical experience with laser-activated bleaching agent for discolored teeth. Extracted human upper central incisors were selected and in a bleaching experiment 35% hydrogen peroxide was used. Three different laser systems and halogen-light unit for activation of the bleaching agent were used: alexandrite laser (wavelength 750 nm and SHG - 375 nm), Nd:YAG laser (wavelength 1.064 μm), and Er:YAG laser (wavelength 2.94 μm). The halogen light unit was used in a standard regime. The enamel surface was analyzed in the scanning electron microscope. The method of chemical oxidation results in a 2-3 shade change in one treatment. The halogen-light unit received the same effect with shorter time of bleaching process (from 630 s to 300 s). Alexandrite laser (750 nm) and bleaching agent helped to reach the desired color shade after shorter time (400 s). Alexandrite laser (375 nm) and Nd:YAG laser had no effect on the longevity of the process of bleaching. Overheating of chemical bleaching agent was visible after Er:YAG laser activation (195 s). This effect was only local, no crack or essential surface modifications were observed.