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Effect of Nd:YAG laser pulse energy on mercury vapor release from the dental amalgam.

OBJECTIVE
The aim of this study was to evaluate the effect of different pulse energies of Nd:YAG laser on the amalgam ablation, and its effect on the amount of mercury vapor release from amalgam.


BACKGROUND DATA
Toxic vapor release from amalgam restorations at the laser focus site is possible.


MATERIALS AND METHODS
Forty-five amalgam samples (4 mm in diameter and 5 mm in height) were placed in sealed containers and underwent Nd:YAG laser irradiation with pulse energies of 50, 150, and 250 mJ at a distance of 1 mm from the amalgam surface for 4 sec. Subsequently, 150 mL of air was collected from the inside of the container using an Apex Pump to analyze the amount of mercury vapor in the air samples using a mercury vapor analyzer. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p<0.05).


RESULTS
The amount of mercury vapor release significantly increased with an increase in the pulse energy of Nd:YAG laser (p<0.001). In addition, the amount of mercury vapor release with 250 mJ pulse energy was significantly higher compared with the standard mercury vapor concentration (50 μg/m(3)) (p<0.001). Nd:YAG laser produced cavities on the amalgam surface, which increased in size with an increase in the energy of the laser beam.


CONCLUSIONS
The amount of mercury vapor significantly increased with an increase in the pulse energy of the laser beam, and was significantly higher than the standard mercury vapor concentration with 250 mJ pulse energy.