Femtosecond laser ablation of dentin and enamel: relationship between laser fluence and ablation efficiency

The objective was to study the relationship between laser fluence and ablation efficiency of a femtosecond laser with a Gaussian-shaped pulse used to ablate dentin and enamel for prosthodontic tooth preparation. A diode-pumped thin-disk femtosecond laser with wavelength of 1025 nm and pulse width of 400 fs was used for the ablation of dentin and enamel. The laser spot was guided in a line on the dentin and enamel surfaces to form a groove-shaped ablation zone under a series of laser pulse energies. The width and volume of the ablated line were measured under a three-dimensional confocal microscope to calculate the ablation efficiency. Ablation efficiency for dentin reached a maximum value of 0.020 mm(3)/J when the laser fluence was set at 6.51 J/cm(2). For enamel, the maximum ablation efficiency was 0.009 mm(3)/J at a fluence of 7.59 J/cm(2). Ablation efficiency of the femtosecond laser on dentin and enamel is closely related to the laser fluence and may reach a maximum when the laser fluence is set to an appropriate value. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)