Fourier-transform Raman spectroscopy study of human dentin irradiated with Er:YAG laser

FT-Raman spectroscopy was used to investigate the influence of the Er:YAG laser irradiation into the human dentin structure. Polished dentin disks with 4mm thickness from six third molars were irradiated with Er:YAG laser. The dentin disks were prepared by polishing through a series of SiO2 papers with water and cleaned by ultrasonic system. Four pretreatment were performed. The disks were etched with 37% phosphoric acid for 15 s (control group), Er:YAG laser 80mJ, 3Hz, and 30s. (Group I), Er:YAG laser 120mJ, 3Hz, 30s. (Group II) and Er:YAG laser 180mJ, 3Hz, and 30s. (Group III). The FT-Raman spectra obtained from normal and treated dentin were analyzed. Attention was paid to the inorganic and organic dentin component (961, 2941cm-1). FT-Raman spectroscopy showed that the mineral and organic content were less affected by the acid etching and by the Er:YAG laser irradiation with 80mJ. Pulse energies of 120 and 180mJ showed to produce more reduction in the organic and inorganic content associated with more reduction in the peak areas at 961 and 2941cm-1. FT-Raman spectroscopy provided information of dentin chemical constituents with non-chemical sampling preparation.