Effect of diferent Nd

Abstract

Because of the possible laser exposure and ablation of the dental amalgam restorations in the patient's mouth during Nd:YAG laser application on oral hard and soft tissues, the aim of this study was to evaluate various intensities of Nd:YAG laser on dental amalgam and its effect on mercury vapor release rate from dental amalgam. Methods and Materials: After preparation of 45 dental amalgam samples (r=4mm, h=5mm) and placing them inside the sealed chamber and Nd:YAG laser radiation in 50, 150, 250 mJ intensities, with a distance of 1mm from the amalgam surface for 4s in 25C,150 mL of the chamber`s air was collected by Apex Pump(Casella Cel, UK) and the mercury vapor levels of samples were analyzed by mercury vapor analyzer )Mercury Analyzer system Shimadzu MAS10,Japan,Tokyo) by atomic absorption method. Data was analyzed using Kruskal-Wallis, Mann-Whitney and One Sample T-test statistical tests. Statistical significance was set at P < 0.05. Results: The results showed that increasing the Nd:YAG laser intensity, the amount of mercury vapor released significantly increased (P < 0.001). Also amount of mercury vapor released in the experimental intensities in comparison with the standard mercury vapor level (0.05 mg/m3 ) were significantly higher (P1,std = 0.004), (P2,std < 0.001),(P3,std < 0.001). SEM-EDXA observations showed that Nd:YAG laser created cavities on the surface of dental amalgam that the cavities size increased with increasing laser intensity. Also with increasing Nd:YAG laser intensity ,the amount of Hg jumping to the surface of quartz slabs increased significantly. Conclusions: The amount of mercury vapor released during dental amalgam ablation with Nd:YAG laser is significantly higher than the standard limit and also it's rate increases significantly with the increasing laser radiation intensity.