Pit Formation in Human Enamel and Dentin Irradiated using the 2.94 μm LEBRA-Free Electron Laser

抄録

The ablation effect of laser treatment of dental tissues is mainly determined by : i) wavelength, ii) power fluence, and iii) pulse structure. To evaluate the effect of pulse structure, the 2.94 μm free electron laser (FEL) and the Er:YAG laser were used to irradiate human tooth enamel and dentin. A 2.94 μm FEL of 8-10 μsec excision with 2 Hz was generated by the 80 MeV LINAC-undulater system at LEBRA, Nihon University, with the macro-pulse structure of 20 μsec and with less than 1 pico-second micro-pulses at 350 pico-sec interval. Size and depth of the pits formed by laser irradiation were measured using a profilometer. Only a 3 mJ LEBRA-FEL was sufficient to form a crater in the enamel and dentin, and the depth of the pit formed by laser irradiation was dependent upon the power of laser. Even when the higher-powered FEL was applied, the craters showed no signs of scorching. Conversely, craters with scorching were evident when the Er : YAG laser was used on dentin. In conclusion, heat damage of dental hard tissues can be avoided using a micro-pulse structured laser.