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To date, no evaluation has been reported about the phase and compositional changes of human dentin after Er:YAG laser irradiation. The aim of this study was to investigate the phase, compositional, and morphological changes of Er:YAG laser-irradiated dentin with or without water spray by means of X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The irradiation energies were from 300 to 700 mJ/pulse-10 pps-10 s. After exposure to Er:YAG laser, dentin showed no phase changes on the X-ray diffractometer. In Fourier transform infrared analysis, two absorption bands at 2200 and 2015 cm −1 could be traced on dentin treated by Er:YAG laser with the irradiation energies beyond 300 mJ/pulse-10 pps-10 s and without water spray. The disappearance of OH − band at 1630 cm −1 could also be found. Scanning electron micrographs revealed that the laser energy of 500 mJ/pulse-10 pps-10 s was sufficient to prompt melting and recrystallization of dentin crystals. Therefore, water spray is important for reducing the thermal effect of Er:YAG laser. |
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