Dental Hard Tissue Ablation Using Picoseconds Pulsed Laser Emitting at 532 and 266 nm Wavelength

The ablation process of the tooth (enamel, dentin and dentin-enamel junction) by 40 ps laser pulses was investigated at 532 nm and 266 nm wavelengths. Fluorescence and scanning electron microscope (SEM) were used as diagnostics. The ablation threshold fluence was measured to be Fth ~ 5 J/cm2 for enamel and for dentin. Ablation at 532 nm laser wavelength produced a crater, both in enamel and dentin, characterized by rough borders. The behavior is completely different at 266 nm wavelength due to the selective behavior towards ablating the intertubular dentin. At 266 nm, the ablation threshold was measured to be Fth ~0.3 J/cm2 for dentin.