Short pulse mid-infrared radiation removal of tooth tissue

The main goal of the work was to investigate the interaction of powerful mid-infrared Er: Cr: YSGG radiation with ivory and dentin. The source of radiation was a free-running or Q-switched Er: Cr: YSGG laser generating 250 mu s or 100 ns pulses (wavelength 2.79 um) with pulse energy 123 mJ or 41 mJ, respectively. Radiation was guided into the irradiated material with a lens of focal length 85 mm. The ablation rate was checked for both the above mentioned regimes as well as for cases without and with water cooling of the interacting material. It has been found that for the long pulse (250 mu s) with energy density 176 J/cm(2) the ablation rate was 0.033 mm(3)/J (without water cooling), while for the short 100 ns pulse with energy density 46 J/cm(2) the ablation rate was 0.012 mm(3)/J (with water cooling).