摘要：Summary. The aim of this work was a scanning electron microscopy (SEM) evaluation of the hardness
and morphological changes of enamel irradiated by neodymium: yttrium aluminium garnet
(Nd:YAG) laser with different energy levels. Twenty-eight human teeth samples were divided into
4 groups: control, where enamel surface was not lased, and 3 test treated with 3 different levels of
energy power 0.6, 1.2 and 2.4 Watt, respectively. In each group, 5 samples underwent Vickers microhardness
test and 2 samples were processed for SEM. No significant differences between treated and
non treated samples were found by micro-hardness test. However, by SEM, test samples showed
a rougher enamel surface than control. Specifically, the 0.6 Watt treated samples showed vertical
scratches and glass-like areas, while in the other 2 groups enamel surface was covered by craters and
cracks. These findings suggest that enamel should be lased at a low energy level to preserve its integrity
and reduce demineralization, and thus for dental caries prevention purposes; while high energy
level creates a retentive surface suitable for sealant or composite anchorage.
关键词：Key words: energy power, micro-hardness, Nd:YAG laser, microscopy, electron, scanning.
