Femtosecond laser ablation of dentin Available to Purchase

The main purpose of this work was to study the changes in structure and composition and the ablation mechanisms of human dentin treated with a femtosecond infrared laser. The laser treatments were carried out using a Yb:KYW chirped-pulse-regenerative amplification laser with a pulse duration of about 500 fs, a wavelength of 1030 nm and fluences ranging from 1 to 3 J/cm2. After the laser treatment, the surface topography was studied by scanning electron microscopy (SEM) and the chemical and structural alterations of dentin investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). By applying this laser, well-defined cavities free of melting, cracks and redeposited debris are easily prepared. The laser treated surfaces are free of smear layer and with open dentinal tubules. They present a rough morphology with flat exfoliated surfaces suggesting that they result from a mechanical disruption process. No significant alterations of the structure and constitution of the dentin due to the laser treatment were observed. A theoretical analysis of the ablation process suggests that ablation occurs by an athermal electrostatic ablation mechanism, explaining the surface morphology and absence of structural changes in the surfaces exposed by ablation. In conclusion, the high beam quality and short pulse duration of ultrafast IR lasers allows the accurate preparation of cavities, with negligible damage of the underlying material.