surface treatment by different parameters of erbium:yttrium–aluminum–garnet (er:yag) laser: scanning electron microscope (sem) evaluation

introduction: this study aimed to assess the scanning electron microscope (sem) analysis of tooth surface irradiated by erbium:yttrium–aluminum–garnet (er:yag) laser with various parameters. methods: number of 25 extracted human third molars free of caries were used in this study. the teeth were put into 5 groups for laser irradiation as follows: group 1 (power: 0.5 w, energy: 50 mj); group 2 (power: 1 w, energy: 100 mj); group 3 (power: 1.5 w, energy: 150 mj); group 4 (power: 2 w, energy: 200 mj); group 5 (power: 2.5 w, energy: 250 mj). all samples were prepared by repetition rate of 10 hz and duration of 230 μs, using a non-contact handpiece at a distance of 4 mm. then, the samples were prepared for sem examination. results: sem evaluation of every 25 samples, treated by er:yag, showed that all groups had exposed dentinal tubules without any melted area or cracks. conclusion: in this study we used sem to investigate ablated dentine with different parameters of er:yag laser energy. our findings support these conclusions. all powers of laser below 3 w are proper for ablation, and make no cracks.