Laser ablation of dental hard tissue: from explosive ablation to plasma-mediated ablation

We review the basic laser ablation processes of dental hard tissue for wavelengths ranging from the IR to the UV. The underlying tissue removal mechanisms extend from water- mediated explosive, to thermomechanical, to plasma-mediated processes. This discussion is based on a literature review of the current state of hard tissue removal under various irradiation conditions combined with some new data using surface temperature measurements. The most effective tissue removal mechanism is the water-mediated explosive process in the IR at wavelengths between 3 and 10 micrometers . Highly controlled tissue removal at low ablation rates can be obtained in the near IR (around 1 micrometers ) using plasma-mediated ablation, provided the irradiation parameters are chosen appropriately. Similarly small ablation rates combined with good tissue specificity characterize the ablation in the UV region of the spectrum. The ablation mechanism in the UV is largely dominated by photothermal processes, although photochemical and thermomechanical processes may contribute.