In VitroStudy of the Nd:YAG Laser Effect on Human Dental Enamel: Optical and Scanning Electron Microscope Analysis

摘要

ABSTRACTObjective:The Nd:YAG laser irradiation of dental enamel was evaluated in enamel demineralization experiments in aStreptococcus mutansculture media.Summary Background Data:Previous studies had shown that a continuous wave Nd:YAG laser at an energy of approximately 67 mJ may induce an increased acid resistance in human dental enamel when exposed to severe demineralization conditions.Methods:Enamel windows of 3 × 4 cm in the buccal surface were irradiated with a continuous wave Nd:YAG laser at a wavelength of 1,064 μm using energy densities of from 83.75 to 187.50 J/cm2. Enamel windows of 3 × 4 cm on the lingual surface served as control (without the laser irradiation). The enamel windows were then exposed to aStreptococcus mutansculture media at a temperature of 37°C for 15 and 21 days. The laser effects and demineralization were examined both by optical microscopy and scanning electron microscopy (SEM).Results:A comparison between the lased and the unlased windows of enamel showed fusion and recrystalization of the enamel and increased acid-resistance in all groups irradiated with the Nd:YAG laser. On the other hand, the 3 × 4 delimited enamel surfaces from the control group (not irradiated with the Nd:YAG laser) showed 100% demineralization.Conclusions:These findings are consistent with the finding that laser irradiation of dental results in significant reduction of the effective solubility of enamel min