Experiment and mechanism investigation on acid resistance of Nd:YAG laser treated enamel

The effectiveness of Nd:YAG laser treatment on in vitro acid resistance of human enamel was studied. After surface polishing, enamel blocks irradiated by different power laser and control group were put into 5 ml of lactate buffer solution (0.1mol/L). which was in water of 37 for 72 hours. The hardness and morphology of enamel surface were investigated by microhardness meter and scanning electron microscopy. Compared with control, the group with 0.3 W laser treatment has the least caries lesion (p<0.001). At the same time, the mechanism of caries prevention and acid resistance by laser was discussed in detail. We drew a conclusion that the change of contents in enamel and crystal orientations and partial decomposition of the organic matrix might be the main reason for enhancing acid resistance. And best caries inhibition could be achieved when the temperature rising of enamel surface was in the range of 300-400/spl deg/C by laser parameters being controlled suitably.