The Influence of Laser Irradiation on The Acid Resistance of Demineralized Enamel Grooves in vitro Daisuke INABA ' , Hisazumi IKEDA " , Okiuji TAKAGI " ' , Masami YONEMITSU ' and Joop ARENDS

Demineralized enamel grooves were exposed to an acid gel at pH=5 for 3weeks after irradiation with a KrF excimer laser with a wavelength of 248nm (total energy dose= 172 J/cm2) er with the second harmonic wave of a Q-switched Nd:YAG laser with a wavelength of 532nm (totai energy dose=100JIcm2), The mineral distributions were assessed quantitatively by transversal microradiography. Compared with unlased controls, the mineral parameters, i.e., the Iesion depth (ld, /!m) and the mineral loss value (AZ, vel%・sJrn) at the bottom of the greoves were not really different in the samples irradiated by either the pulsed excimer or the Nd : YAG laser, and a similar result'was observed in the outer enamel surfaces near the groeves. This suggest that progression of demineralization in enamel lesions is not inhibited effectively by laser irradiation.