Examination of dental hard tissues after short pulse Nd:YAG laser irradiation

Abstract

In the course of high intensity laser irradiation, expressive chemical and physical alteration may be induced in the irradiated dental tissues. We used short pulse Nd:YAG laser, with which damage in the tissue is reduced and thermal load can be better controlled. The use of nano and picosecond pulselengh also assures better accuracy in affected zone as well a smaller deepness. In one of the experiments, specimens were irradiated with different energy densities in a unique track of the laser beam on the enamel surface. Laser parameters used were: pulse width 6ns, energy densities from 10J/cm2 to 40J/cm2 and focused beam diameter of 0.1cm. In this case, the area of affected zone was 3 times higher than expected. In other experiment, bursts of shorter laser pulse width were used. In this case the laser emissin was formed by bursts composed of a train of 10 pulses with 100 ns of pulse width each. Energy densities from 10J/cm2 to 22.5J/cm2 and a focused beam diameter of 0.06cm were used. Heat affected zone was determined by Scanning Electron Microscopy, which showed a direct relationship between energy employed and morphological changes and as a result of dental tissue damage dimension.