Influence Of Erbium Laser In Diffeerent Parameters Cutting Efficiency Dental Hard Tissue

Objective:We sought to improve the mass of dentin ablation with the Er:YAG laser by assessing the influence of energy and pulse repetition rate on ablation ability and substrate morphology.Methods:Crowns of molars were sectioned in two fragments, providing150samples, whose initial masses were obtained by weighing the fragment.. Fifteen groups were randomly formed according to the combination of laser energies,pulse repetition rates and output power. The final masses were obtained and mass losses calculated by the differences between the initial and final masses. Data were submitted to ANOVA,Scheffe test and correlation analysis.The ablated surfaces of specimens were examined by scanning electron microscopy.Results:1,The maximum cutting efficiency is the 5 group 15Hz, 450mJ, 6.75W, the 9 group 20Hz, 400mJ, 8W and group 10Hz,500mJ,5W.2,The 6 group resulted in higher mass loss and was statistically different from other goups( p < 0.05). The 5 group,The 3group and the 5 group were not statistically different from each other.3,The output energy and pulse repetition rate showed a positive correlation with the mass of ablation, correlation coefficient were respectively 0.813,0.290(p﹤0.05)4,The 6 groups was more surface morphological alteration with deep fissures and fused areas.Conclusion:1,The output energy and pulse repetition rate was positively correlated with the mass of ablation, and the correlation coefficient of output energy was greater than the energy pulse repetition frequency′s.2,Among the tested parameters, the best working parameters of erbium laser is 15Hz,450mJ,6.75W, 20Hz,400mJ,8W and 10Hz,500mJ,5W.