Enamel Color Changes After Bleaching Treatment Using Common Bleaching Agents With Er, Cr:YSGG Laser

Reports indicate that lasers accelerate tooth bleaching by activating bleaching agents. Due to the lack of sufficient information about the application of the Er, Cr:YSGG laser, the present study was conducted to compare the degree of enamel color changes after teeth bleaching treatment using chemical whitening agents alone and with Er, Cr:YSGG laser.

In this laboratory study, several human molars were cut into 4 parts after cutting and removing the pulp. Based on laser application, the samples were randomly divided into two groups (N=20), including the chemical bleaching group (G1) and the chemical bleaching group with activated laser (G2). In G1, the bleaching process was performed only with 35% hydrogen peroxide for two weeks (3 times, 15 minutes each week). In G2, the gel bleaching was activated by the Er, Cr:YSGG laser with a wavelength of 2780 nm. It was placed 2.5 cm from the sample surface with bleaching agents and applied twice for 15 seconds. Color changes were recorded using a spectrophotometer before bleaching, immediately after, 1 month, and 3 months after bleaching. Data were analyzed by SPSS software (version 18), Repeated measures ANOVA, and Tukey’s tests (α=0.05).

Mean and standard deviation of changes in Δa showed a significant difference between the gel group and the gel group with laser over time (P<0.05), but this difference was not observed in ΔL and ΔB (P>0.05). However, the intragroup comparison demonstrated significant changes in Δa and Δb in both groups over time, but not in ΔL (P>0.05). The ΔE changes in both the laser and bleaching gel groups were above the threshold of 3.3. The results indicated no significant difference between G1 and G2 in terms of the ΔE (P>0.05). Finally, the results revealed that 1 and 3 months after teeth whitening, ΔE changes in both groups were greater than 3.3.

Overall, the application of the Er, Cr:YSGG laser had no positive effect on bleaching efficacy when using a 35% hydrogen peroxide gel. Based on the findings, color changes were stable in the studied groups for up to 3 months after teeth bleaching.