Laser-enhanced tooth bleaching with Nd:YAG, Er:YAG, and diode lasers: an in vitro study

Tooth discoloration and staining are aesthetic issues that trouble many patients. The purpose of this study is to compare tooth color change after bleaching with Nd:YAG, Er:YAG, and diode lasers. Forty-eight upper and lower human anterior teeth and premolars were divided into four groups (12 teeth each). Bleaching gel with 38% hydrogen peroxide was placed on the teeth in all four groups. In the first, second, and third groups, Nd:YAG laser, Er:YAG laser, and diode laser were irradiated after applying the bleaching gel. In the fourth group, which is considered as control group, no laser rays were irradiated for activation after the bleaching gel was placed. Before and after bleaching, the shade of the teeth was measured using the CIELab system by a spectrophotometer (SpectroShade, MHT, Verona, Italy). The results were analyzed using one-way ANOVA and Tukey’s multiple comparison test. All bleaching methods resulted in significant changes in tooth shade (ΔE≥3.3). The average color changes between groups differed significantly (p<0.05). Diode laser caused the highest (ΔE=10.16), and Er:YAG laser caused the lowest amount of color change among all groups (ΔE=5.14). There was no difference between the Nd:YAG and Er:YAG lasers (p>0.05). The color change in the diode laser group was significantly higher than in the control group, whereas it was lower in the Er:YAG and Nd:YAG groups.