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.