This clinical study evaluated the effect of light activation on the whitening efficacy and safety of in-office bleaching system containing 15% hydrogen peroxide gel.

Thirty-three volunteers were randomly treated with (n = 17, experimental group) or without light activation (n = 16, control group), using Zoom2 white gel (15% H₂O₂, Discus Dental) for a total treatment time of 45 min. Visual and instrumental color measurements were obtained using Vitapan Classical shade guide and Shadepilot (DeguDent) at screening test, after bleaching, and 1 month and 3 month after bleaching. Data were analyzed using t-test, repeated measure ANOVA, and chi-squared test.

Zoom2 white gel produced significant shade changes in both experimental and control group when pre-treatment shade was compared with that after bleaching. However, shade difference between two groups was not statistically significant (p > 0.05). Tooth shade relapse was not detected at 3 months after bleaching. The incidence of transient tooth sensitivity was 39.4%, with being no differences between two groups.

The application of light activation with Zoom2 white gel system neither achieved additional whitening effects nor showed more detrimental influences.