Fiber-tip drilling of hard dental tissues with Er:YAG laser

Specifics of fiber-tip ablation of hard dental tissues with mid-infrared laser radiation are investigated in vitro. Sequences of free-generated Er:YAG laser pulses are applied to fresh human dentin and enamel slices at a low repetition rate and the resulting craters inspected and measured by optical microscopy. Influence of the laser pulse fluence (up to 55 J/cm2), number of pulses in the sequence (1 to 20), and the gap between the fiber tip and the tissue surface (0 to 1.0 mm), is determined quantitatively. Additionally, the effect of the optical quality of the fiber tip on the ablation efficiency is assessed qualitatively. The results help us identify the optimum working regime for the dental fiber-tip handpieces in both tissues. Additionally, they provide new clues for understanding the process of mid-infrared ablation of hard biological tissues, especially in presence of the water spray, which interacts directly with the laser radiation.

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