Effect of bleaching agents on the fluorescence of composite resins.

As the demand for an esthetically satisfactory smile has increased, interest in less invasive procedures, such as composite restoration and tooth bleaching, has also increased. Composite resins exhibit several optical properties, including fluorescence, which are intended to mimic the natural dentition. The aim of this study was to evaluate the effect of hydrogen peroxide (HP) bleaching protocols for home and in-office applications on the fluorescence of composite resins. Sixty composite resin specimens (shade A2) were divided into 2 groups of 30 each according to the material type (groups R1 and R2 were made up of 4 Seasons and Opallis specimens, respectively). Each group was subdivided into 3 subgroups (n = 10) according to the bleaching protocol administered: home application (HP 7.5%); in-office application (HP 35%); and control (Co), immersion in deionised water. The fluorescence intensities were measured before and after the bleaching treatments using a Cary Eclipse fluorescence spectrophotometer and statistically analysed by paired t test, Student's t test, analysis of variance (ANOVA), and Tukey's multiple comparison test (P < 0.05). Significant differences between groups R1 and R2 after the different treatments were noted. The fluorescence intensities differed across the subgroups after 30 days of treatment. The HP 7.5% protocol induced the greatest change in the fluorescence intensities among the specimens in the R1 group.