Laser-induced breakdown spectroscopy (LIBS) analysis of human dental tissues: enamel and dentine, performed by utilizing Nd: YAG laser (𝜆=1064 𝑛𝑚, 𝜏=6 𝑛𝑠, 𝐸=50 𝑚𝐽) to investigate threshold ablation of laser energy density. Quantitative results based on the experiment provide us with threshold ablation value of laser energy density for calcium (Ca) ablation in enamel and dentine tissues. The computed threshold laser energy density for Ca ablation in dentin tissue is 0.38 J/cm2, which is significantly lower than the threshold in the enamel, which is 1.41 J/cm2. Scanning electron microscopic (SEM) examination of dental tissues determines that the dentin surface contains pores, voids, and bubbles that make it easy to ablate at low laser energy density, while enamel has a closely packed smear layer structure that is difficult to ablate, requiring high energy densities. These findings are helpful in the field of laser dentistry, where lasers are widely used for dental treatment.

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