Abstract
The aim of this study was to examine the influence of timing of laser irradiation on acid resistance of remineralized enamel. Sixty enamel samples were prepared for this study, and they were divided into 4 groups. Each sample was demineralized by lactic acid buffer, and 2 groups were irradiated with a Q-switch Nd-YAG laser. One of the lased groups and one of the unlased groups were remineralized with fluoride, and the others were remineralized without fluoride. After remineralization, the unlased groups were irradiated with a Q switch Nd-YAG laser. After all treatments were finished, the samples were immersed in 0.1M lactic acid solution, and dissolved calcium was measured as a function of time from 15 to 180 minutes.
After an immersion of 15 minutes, the dissolved calcium of the remineralized with fluoride and lased group was lowest, so the highest acid resistance was found in this group. There was no statistical difference between the other 3 groups. This result suggested that laser irradiation was effective on mineral rich enamel. However, after an immersion of more than 30 minutes, there was no influence on the timing of laser irradiation, but it depended on the condition of remineralization. Therefore laser irradiation of demineralized enamel before remineralization made in easy to destroy the surface.
