Color Change Stability Using Different Bleaching Gels and Light Sources: An in Vitro Study

<b>Objectives:</b> The aim of this study was to assess the color change (∆E) of teeth following the use of several bleaching protocols with power bleaching. <b>Materials and Methods:</b> This in vitro study evaluated 50 sound incisors and premolars. After cleaning, the teeth were immersed in a 2g/100mL tea solution for 6 days. The samples were randomly divided into 5 bleaching groups: Snow L [containing 40% hydrogen peroxide (HP) and 20% carbamide peroxide] with 980nm diode laser, White Smile (containing 32% HP) with LED (Monitex), Boost (containing 40% HP) with 980nm diode laser, Boost (containing 40% HP) with LED (Monitex), and Boost without activation. Color parameters were measured before and after staining, immediately and 1 week after bleaching by a spectrophotometer, and their ∆E was calculated and compared by one-way ANOVA followed by the Tukey's test. <b>Results:</b> All bleaching protocols improved the color parameters. The ∆E in each group was significant after bleaching compared to before bleaching in the cervical (P<0.001), middle (P<0.001) and incisal (P<0.001) thirds. The ∆E was significant at 1 week compared to before bleaching (P=0.002 for the cervical, P<0.001 for the middle, and P<0.001 for the incisal third, respectively), immediately after bleaching compared with after staining (all Ps<0.001), and also at 1 week compared with after staining (all Ps<0.001). <b>Conclusion:</b> Within the study limitations, all power bleaching protocols caused color change of the teeth. The efficacy of Boost (conventional bleaching), Boost plus LED, and White Smile was better than Snow L regarding color change of teeth.