Enamel Color Changes After Bleaching Treatment Using Common Bleaching Agents With Er, Cr:YSGG Laser abstract
Background: 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.
Methods: 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).
Results: 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.
Conclusions: 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.